The dog was referred to the Veterinary Clinic of the Faculty of Veterinary Medicine at the University of Tehran with a striking dermatological picture. It lived outdoors under unsanitary conditions with regular exposure to vegetation and soil, and it presented with diffuse hair loss, marked redness, itching and scaling across the skin of its back. Crucially, there was no ulceration or open wound, no lethargy and no loss of appetite, so systemic illness seemed unlikely and a complete blood count was not performed. The owner declined a skin biopsy, which meant the team could not obtain histopathological evidence of fungal invasion, a detail that would later shape how carefully the conclusions had to be framed. Hair plucks and skin scrapings were collected from the affected areas under sterile conditions and sent to the laboratory for fungal examination.

The initial diagnostic workup followed the standard playbook for suspected dermatophytosis, the superficial fungal infection of keratinized skin that is usually caused by organisms such as Microsporum canis, Microsporum gypseum or Trichophyton mentagrophytes. A Wood’s lamp examination was negative, and a direct microscopic examination of material treated with 10 percent potassium hydroxide also failed to reveal fungal elements. But the story changed when the samples were cultured on Sabouraud Dextrose Agar. After incubation at 28 degrees Celsius, colonies emerged that were creamy-brown and powdery with a colorless reverse surface. Lactophenol cotton blue staining of the growth revealed thin, septate hyphae studded with large, round, warty conidia, a morphological signature that immediately suggested the team was not dealing with a routine dermatophyte.

Seeking to probe the organism’s thermal behavior, the researchers subcultured the colonies onto blood agar and incubated them at 37 degrees Celsius, close to mammalian body temperature, for five days. The fungus produced creamy, dome-shaped, mucoid colonies under these conditions, and Giemsa staining revealed round-to-oval yeast-like cells with budding and point attachments when viewed under oil immersion at 100 times magnification. This dimorphic tendency, the ability to alter its appearance under different growth conditions, added another layer of complexity to the identification. Morphology alone could not settle the question, particularly since members of the family Chaetomiaceae, to which Corynascus belongs, are notorious for overlapping phenotypic features among closely related species. The team therefore turned to the laboratory’s molecular arsenal.

Genomic DNA was extracted from the isolate using a commercial fungal DNA extraction kit, and the internal transcribed spacer region of ribosomal DNA, comprising the ITS1 spacer, the 5.8S rRNA gene and the ITS2 spacer, was amplified with the universal primers ITS1 and ITS4. The polymerase chain reaction protocol began with denaturation at 94 degrees Celsius for three minutes, followed by 37 cycles of denaturation for 30 seconds, annealing at 60 degrees Celsius for 30 seconds and extension at 72 degrees Celsius for 30 seconds, with a final extension of eight minutes. The roughly 600-base-pair amplicon was then sequenced, and the resulting sequence was deposited in GenBank under accession number PV082530, making it publicly available for future comparisons by researchers anywhere in the world.

The sequence told a clear story. BLAST analysis showed 99.36 percent nucleotide similarity to reference sequences of Corynascus verrucosus and 99.34 percent similarity to a reference sequence of Corynascus sepedonium, a closely related species whose ITS region differs only marginally. To resolve the placement further, the researchers aligned their sequence with reference data from GenBank and constructed a maximum likelihood phylogenetic tree in MEGA7 using the Kimura two-parameter model with 1000 bootstrap replicates. The Iranian isolate fell squarely within the broader Corynascus lineage and clustered tightly with C. verrucosus sequences from different geographic regions, while reference sequences annotated as Myceliophthora, including Myceliophthora sepedonium and Myceliophthora verrucosa, occupied the same larger assemblage. The tree was rooted with Amesia atrobrunnea as the outgroup, and the resulting topology was consistent with previously published taxonomic frameworks placing Corynascus within the family Chaetomiaceae.

The taxonomy behind that placement is itself a story of scientific revision. The genus Corynascus comprises seven recognized species, and its boundaries have shifted repeatedly over decades of study, from early work by von Klopotek in 1974 and Stchigel and colleagues in 2000, who described three new thermotolerant species, to a 2015 re-evaluation of Myceliophthora using morphological and multilocus phylogenetic data that affirmed Corynascus as a distinct genus. More recent comprehensive studies have supported that distinction using multigene analyses incorporating ITS, LSU, rpb2, tub2 and tef sequences. Meanwhile, members of the Myceliophthora lineage have attracted industrial attention for their production of thermostable enzymes, and C. verrucosus itself made headlines in 2020 when researchers documented it as a mycoendophyte of Croton bonplandianus and a potential source of bioactive metabolites active against multidrug-resistant pathogens and cancer cells. None of this industrial or pharmacological relevance implies pathogenicity, a distinction the authors are careful to draw.

Where might a pet dog have encountered such a fungus? Environmental studies of composting offer a suggestive clue. Research on organic waste and manure composting has documented substantial shifts in fungal community composition as physicochemical conditions change, with thermophilic and thermotolerant fungi, exactly the ecological guild to which many Corynascus species belong, flourishing in these habitats. Composting environments and similar organic-material settings may therefore serve as reservoirs of environmentally adapted fungal taxa. The Tehran patient’s outdoor lifestyle, unsanitary surroundings and regular contact with soil and vegetation provided ample opportunity for exposure. Still, the authors emphasize that phylogenetic relatedness does not imply shared biological function or pathogenic potential, and that genetic similarity alone should never be read as evidence of a shared disease-causing role.

The clinical narrative, however, lends weight to a genuine association rather than a chance contaminant. The same fungal species was recovered on three independent cultures from the lesion, no bacterial growth was detected, and mite infestation was excluded. The dog was treated with oral ketoconazole combined with ketoconazole shampoo, receiving four weekly medicated baths. The itching and redness resolved within about a month, hair regrowth followed, and a uniform coat had returned approximately six months after treatment began. Over a nine-month follow-up period, the original cutaneous signs never recurred. The combination of repeated isolation, exclusion of other pathogens, molecular identification and clinical improvement following antifungal therapy supports, though it does not prove, a causal link.

That caution about proof is the intellectual heart of the report. Because histopathological examination was never performed, tissue invasion by the fungus could not be demonstrated directly, and the authors explicitly frame the finding as an association rather than definitive evidence of causality. Their broader message concerns method: for uncommon environmental fungi recovered from veterinary specimens, accurate identification demands a polyphasic approach that integrates morphology, ITS sequencing and phylogenetic placement rather than relying on any single line of evidence. Molecular methods can rescue isolates that fail to produce characteristic reproductive structures in culture, but they carry their own biases and limited discriminatory power, as the near-identical ITS sequences of C. verrucosus and C. sepedonium illustrate. By expanding the documented occurrence of C. verrucosus to a canine cutaneous lesion, the case adds a small but genuinely novel data point to veterinary mycology and a reminder that the fungal world’s opportunists may be more numerous, and better camouflaged, than current diagnostics routinely reveal.

Subject of Research: A rare case of cutaneous infection by the environmental fungus Corynascus verrucosus in a Shih Tzu dog, identified through molecular and phylogenetic analysis.

Article Title: A Rare Case of Cutaneous Infection by Corynascus verrucosus in a Shih Tzu Dog: Molecular Identification and Phylogenetic Analysis

Article References: Ghahremani, M., Sharifzadeh, A., Ashrafi Tamai, I., & Faridfar, G. (2026). A Rare Case of Cutaneous Infection by Corynascus verrucosus in a Shih Tzu Dog: Molecular Identification and Phylogenetic Analysis. Veterinary Medicine and Science, 12(5), Article e71205. https://doi.org/10.1002/vms3.71205

Image Credits: AI Generated

DOI: 10.1002/vms3.71205

Keywords: Corynascus verrucosus, veterinary mycology, canine dermatology, fungal infection, ITS sequencing, phylogenetic analysis, Chaetomiaceae, dermatophytosis, Shih Tzu, molecular identification, environmental fungi, ketoconazole treatment

Candidozyma auris has earned a reputation as one of the most concerning healthcare-associated fungal pathogens of the modern era. Unlike many of its fungal relatives, it persists stubbornly in the hospital environment, colonizes surfaces and medical equipment, spreads between patients in healthcare facilities, and frequently displays resistance to the antifungal drugs clinicians rely upon most. First recognized as a human pathogen less than two decades ago, it has since been reported on multiple continents, triggering outbreaks in intensive care units and prompting public health agencies to classify it as a serious global health threat. Its ability to survive routine disinfection and to be misidentified by conventional laboratory methods has made containment exceptionally difficult, and each new clinical dataset contributes valuable intelligence about how the organism behaves in actual patient care.

The Turkish research team set out to answer a question that has divided the field: does C. auris candidemia actually kill more patients than candidemia caused by other Candida species, or does it merely appear more lethal because it disproportionately infects patients who are already gravely ill? To address this, the investigators conducted a single-center retrospective cohort study, identifying every adult patient with candidemia seen at their institution and classifying infections by species. Identification was performed using MALDI-TOF mass spectrometry, a rapid proteomic technique that has become the gold standard for distinguishing C. auris from look-alike yeasts that older biochemical panels frequently confuse with it. Accurate speciation matters enormously here, because misidentification has historically hampered both surveillance and appropriate treatment.

The clinical profiles of the two patient groups differed in telling ways. Patients with C. auris candidemia had spent significantly longer in the hospital before their bloodstream infection developed, a pattern consistent with a healthcare-associated pathogen that colonizes patients during extended stays. They also more frequently had central venous catheters, the indwelling lines that provide fungi with a direct portal into the bloodstream, and greater exposure to corticosteroids, which suppress immune defenses. These exposures are classic risk factors for invasive candidiasis in general, but their heightened frequency in the C. auris group underscores how thoroughly this organism is woven into the fabric of modern intensive medical care. The findings reinforce the picture of C. auris as an opportunist that exploits the very devices and drugs that keep critically ill patients alive.

When the researchers examined crude outcomes, the headline number was striking in its symmetry: 30-day all-cause mortality was 62.3 percent among patients with C. auris candidemia and 62.5 percent among those with non-auris Candida infections, a difference of essentially zero. On the surface, this suggests the emerging pathogen is no deadlier than its established cousins. But crude comparisons in observational data can be deeply misleading, and the investigators knew that the patients harboring C. auris arrived at their infections with a different constellation of vulnerabilities. To disentangle the effect of the organism itself from the effect of patient characteristics, they turned to more sophisticated statistical machinery.

The team employed a multivariable Firth-penalized logistic regression model, a technique designed to produce more stable estimates when outcomes are imbalanced or sample sizes are modest, and they handled missing data through multiple imputation. The model was constructed with clinical input to ensure that the variables adjusted for reflected genuine medical knowledge rather than statistical convenience. After adjustment, C. auris candidemia was associated with higher estimated odds of 30-day mortality, with an adjusted odds ratio of 1.967, meaning the odds of death were nearly doubled relative to non-auris candidemia. However, the 95 percent confidence interval ranged from 0.954 to 4.055 and included the null value of one, with a p value of 0.067, meaning the association fell just short of conventional statistical significance.

To translate the regression results into more intuitive risk terms, the researchers used g-computation to estimate standardized marginal mortality risks. Under this approach, the adjusted 30-day mortality was estimated at 69.7 percent for C. auris candidemia compared with 59.3 percent for non-auris Candida candidemia, corresponding to an adjusted risk difference of 10.4 percentage points, with a confidence interval spanning from minus 0.2 to plus 21.3 points. In other words, once patient severity was accounted for, the data hinted that C. auris infections carry a genuinely elevated mortality burden, potentially adding roughly ten deaths per hundred patients, but the uncertainty around that estimate means the true effect could range from negligible to substantial. The authors are explicit that these findings should be interpreted as associative rather than causal, and that larger prospective multicenter studies across diverse healthcare settings are needed to confirm them.

Beyond the comparison between species, the study identified the factors that independently predicted death within 30 days across the entire cohort. Older age, higher scores on the Sequential Organ Failure Assessment, or SOFA, scale, the presence of septic shock, corticosteroid use, and hemodialysis were all associated with higher adjusted odds of mortality. These determinants are familiar from the broader candidemia literature: they reflect the reality that bloodstream fungal infections are most lethal in patients whose organs are already failing and whose immune systems have been blunted by illness or medication. The consistency of these predictors with prior research lends credibility to the study’s methodology and suggests the dataset behaves as expected, strengthening confidence in the species-specific comparisons.

The antifungal susceptibility findings carry important practical implications for treatment. Among C. auris isolates, echinocandin non-wild-type phenotypes were uncommon, which is welcome news because echinocandins are the recommended first-line therapy for invasive candidiasis and are often the drug class of choice against C. auris. However, elevated minimum inhibitory concentrations for amphotericin B were observed in approximately one-third of tested isolates, a troubling signal for an older but still-used antifungal that clinicians may reach for when first-line options fail or are unavailable. Meanwhile, resistance to fluconazole was frequent among tested Candida parapsilosis isolates, a reminder that antifungal resistance is not confined to the emerging pathogen and that susceptibility testing remains essential for guiding therapy across all Candida species. Susceptibility results were interpreted using applicable EUCAST clinical breakpoints or epidemiological cut-off values, and where no interpretive criteria existed, results were reported descriptively, reflecting the ongoing challenge that interpretive standards for some antifungal-organism combinations are still evolving.

The study’s conclusions are measured but consequential. C. auris candidemia, the authors report, is characterized by a distinct profile of healthcare-associated exposures and a distinct antifungal susceptibility pattern, and while crude mortality appears similar to other candidemia, adjusted estimates point toward higher mortality that remains statistically imprecise. For clinicians, the message is twofold: patients colonized or infected with C. auris deserve vigilant attention to modifiable risk factors such as catheter management and careful stewardship of corticosteroids, and treatment decisions should be anchored in susceptibility data rather than assumptions. For public health officials, the findings add to the accumulating evidence that C. auris is not simply another Candida species but a pathogen with its own epidemiology, its own resistance landscape, and potentially its own mortality penalty. As the global footprint of this fungus continues to expand, studies like this one, grounded in real-world clinical data and rigorous statistical adjustment, will be essential for calibrating the response. The research received no specific funding, was approved by the Etlik City Hospital clinical research ethics committee, and was conducted in accordance with the Declaration of Helsinki, with the requirement for informed consent waived given its retrospective design.

Subject of Research: Comparison of clinical characteristics, antifungal susceptibility, and 30-day mortality in Candidozyma auris versus non-auris Candida candidemia

Article Title: Clinical characteristics, treatment strategies, and factors associated with 30-day mortality in Candidozyma auris versus non-auris Candida candidemia: a retrospective cohort study

Article References: Kuzi, S., Çiçek Şentürk, G., Kul, G., Haykır, A., Yılmaz, N., Korkmaz, N., Bulut, D., Aslan, M., Yapar Toros, G., Şencan, İ., & Tütüncü, E. E. (2026). Clinical characteristics, treatment strategies, and factors associated with 30-day mortality in Candidozyma auris versus non-auris Candida candidemia: a retrospective cohort study. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14401-4

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14401-4

Keywords: Candidozyma auris, candidemia, antifungal resistance, 30-day mortality, bloodstream infection, echinocandins, amphotericin B, fluconazole resistance, septic shock, healthcare-associated infection, MALDI-TOF, risk factors

The central insight of the review is that nutrient limitation operates in two interconnected modes. On one hand, starvation is a metabolic stress that passively restricts growth by depriving cells of the energy and building blocks needed for proliferation. On the other hand, and more strikingly, nutrient scarcity functions as information: it tells the fungus that continued local growth is becoming unprofitable and that dispersal, dormancy, or recombination may offer better future returns. This adaptive duality, the authors argue, has driven the evolution of precise sensing pathways that transform an environmental deficit into an anticipatory cue for fitness realignment. The result is a developmental window in which fungi can commit to reproduction, but only if they retain enough physiological competence to complete the costly program.

The clearest illustration comes from budding yeast, Saccharomyces cerevisiae, which enters meiotic sporulation only under a specific combination of conditions: the cells must be diploid with both mating types, starved of nitrogen, depleted of fermentable glucose, and supplied with a non-fermentable carbon source such as acetate. Each element of this recipe is physiologically coherent. Nitrogen limitation reduces the value of mitotic division, glucose depletion lifts repression of respiratory and meiotic programs, and acetate fuels meiosis and spore-wall construction. Under nutrient-rich conditions, the conserved cAMP-PKA and TOR signaling pathways promote growth and actively suppress meiotic genes; when conditions turn unfavorable, that repression is relieved and the master meiotic regulators IME1 and IME2 are induced. Sporulation, in other words, is a conditional developmental program, not a nonspecific starvation collapse.

Fission yeast, Schizosaccharomyces pombe, achieves a similar outcome through a different regulatory architecture. Nitrogen starvation is the principal cue that triggers sexual differentiation: compatible mating types arrest in the G1 phase of the cell cycle, mate, fuse their nuclei, enter meiosis, and produce stress-resistant spores. The pathway runs through the transcription factor Ste11, which induces mating and meiotic genes once growth-promoting cAMP-PKA and TOR signals subside. Commitment is then controlled by a molecular switch involving the Pat1 kinase and the RNA-binding protein Mei2. During vegetative growth, Pat1 phosphorylates Mei2 and marks it for destruction; upon nitrogen starvation and successful conjugation, the inhibitor Mei3 is expressed, Pat1 is inactivated, and the cell becomes irreversibly committed to meiosis. The comparison between the two yeasts supports a modular model in which conserved nutrient-sensing pathways feed into species-specific reproductive circuits.

Filamentous fungi add further layers of complexity. In Aspergillus nidulans, the best-defined genetic model, asexual development depends on the BrlA-AbaA-WetA transcriptional cascade, with BrlA initiating conidiophore construction, AbaA directing phialide differentiation, and WetA ensuring spore maturation and long-term viability. Upstream regulators such as FluG and the Flb proteins connect colony state to this central cascade, while light and the Velvet complex bias the outcome: light generally favors asexual conidiation, whereas darkness promotes sexual development through the nuclear accumulation of the VeA protein. In Neurospora crassa, the White Collar Complex and the FRQ-based circadian clock generate rhythmic conidiation, timing spore production to predictable daily cycles. In plant pathogens such as Magnaporthe oryzae and Fusarium graminearum, nutrient limitation intertwines with host-derived stresses, and the resulting spores, conidia in rice blast or airborne ascospores in Fusarium head blight, are the engines of epidemic spread.

Human fungal pathogens reveal the clinical stakes of these switches. In Candida albicans, the white-opaque epigenetic switch has long been considered a prerequisite for mating, but recent work shows that glucose depletion can bypass it entirely, rendering white cells mating-competent without the switch. Phosphate limitation, acting through the PHO pathway, can similarly induce the opaque state even in otherwise mating-incompetent cells. In Cryptococcus neoformans, whose sexual reproduction produces the basidiospores that serve as primary infectious propagules, all fourteen core autophagy genes are required for meiotic progression and spore formation, and the heme activator protein complex links iron homeostasis directly to sexual development by repressing the pheromone-responsive Cpk1 MAPK pathway. These findings underscore that nutrient sensing and reproductive commitment are deeply entangled even under host-imposed selection.

Perhaps the most striking recent discovery concerns a post-transcriptional layer of control. In the class Sordariomycetes, sexual development is accompanied by extensive adenosine-to-inosine mRNA editing, mediated not by the animal-style ADAR enzymes but by a fungal-specific Tad2-Tad3-Ame1 complex. Because inosine is read as guanosine during translation, this editing generates transcript-level changes that alter codons without touching the genome. The editing occurs almost exclusively during fruiting-body development and ascospore formation, and experimental studies in Fusarium and Neurospora show that it contributes to perithecium development, meiosis, and spore maturation through targets such as Dbf2, Mus81, and Spo11. Crucially, by restricting reproduction-beneficial protein variants to the sexual phase, editing allows fungi to preserve vegetative stress resilience, such as Mus81-dependent heat tolerance, while still meeting the distinct genetic demands of meiosis, elegantly resolving the antagonistic pleiotropy between survival and reproduction.

Why should a fungus pay the steep cost of sex when clonal spores can disperse and survive just as well? The review evaluates two evolutionary frameworks. Fitness-associated sex theory proposes that low-fitness individuals benefit from recombination because sex allows alleles to escape maladapted genetic backgrounds. Experimental work in Aspergillus nidulans supports this: sexual reproduction is associated with low-fitness conditions, and sublethal fungicide stress increases outcrossing, with recombinant offspring showing improved performance under stress. The abandon-ship framework extends the logic, treating dispersal, dormancy, and sex as alternative escape routes from a deteriorating situation: escape in space through conidia, escape in time through chlamydospores and sclerotia, and escape in genetic identity through recombination. Both models predict that the beneficiaries of stress-induced sex may be the recombinant offspring rather than the stressed parent, a distinction that demands careful measurement of parental condition, propagule quality, and descendant performance.

The practical implications are substantial. In industrial biotechnology, a rational two-phase strategy, first building biomass under favorable conditions and then applying controlled developmental cues, can maximize yields of viable, stress-tolerant spores for biocontrol agents, inoculants, and fermentation starters, with mechanistic markers such as conidiation-regulator expression guiding the timing of the shift. In agriculture and medicine, anti-sporulation interventions range from highly specific targets such as the BrlA and WetA transcription factors to broader signaling nodes and environmental management of light, humidity, and crop residues. Yet the authors caution that conserved regulators carry risks for beneficial fungi and that strong selective pressure under field conditions can drive pathogens toward altered sporulation kinetics or cryptic alternative pathways. The review closes with a call for causal, ecologically grounded models that link environmental perception, molecular regulation, reproductive output, and fitness consequences, moving the field from describing stress-associated reproduction to predicting and ultimately manipulating fungal life-history decisions.

Subject of Research: Stress-driven sporulation and sexual development in fungi

Article Title: When growth becomes risky: stress-driven sporulation and sexual development in fungi

Article References: Yang, J., Wang, Q., & Liu, H. (2026). When growth becomes risky: stress-driven sporulation and sexual development in fungi. Stress Biology, 6(1), Article 55. https://doi.org/10.1007/s44154-026-00333-1

Image Credits: AI Generated

DOI: 10.1007/s44154-026-00333-1

Keywords: fungal development, sporulation, sexual reproduction, nutrient limitation, stress signaling, cAMP-PKA, TOR signaling, HOG MAPK, Velvet complex, A-to-I RNA editing, fitness-associated sex, disease management

The research began in the field. Specimens were collected from Gool in District Ramban, at altitudes of roughly 2,500 to 3,500 meters above sea level, during the monsoon months between June and August. The club-shaped, orange stromata the researchers found were closely associated with insect larvae and pupae, whose bodies the fungus had colonized and mummified with its mycelium. Back at the Plant Pathology, Mycology and Microbiology Laboratory in Srinagar, the team documented the fungus’s macroscopic anatomy in detail, noting stromata measuring 3.8 to 6.2 centimeters in length, semi-immersed ovoid perithecia, and the darker fertile heads that signal maturity.

Identification did not rest on appearance alone. Microscopic examination revealed subcylindrical conidiophores, slender flask-shaped phialides, and variably shaped conidia, along with eight-spored cylindrical asci containing filiform ascospores. The researchers then turned to molecular tools, extracting DNA by the CTAB method and amplifying the internal transcribed spacer region of the ribosomal DNA with the universal primers ITS-1F and ITS-4R. Sequencing showed 99.78 percent identity with a reference strain of C. militaris, and the sequence was deposited in GenBank under accession number PQ810010. A maximum-likelihood phylogenetic analysis of 18 ITS sequences placed the Kashmir isolate firmly within the C. militaris species complex, supported by a bootstrap value of 100 percent. The specimen itself was preserved as voucher number 9337-KASH in the herbarium at the University of Kashmir.

With identity confirmed, the researchers set out to solve a practical problem: the fungus grows slowly. On ordinary Sabouraud’s dextrose agar, C. militaris needed roughly 27 to 28 days to cover a plate, and the full cultivation cycle to mature stromata in prior work stretched to two or three months. For a fungus whose value lies in compounds such as cordycepin, adenosine, gamma-aminobutyric acid, ergothioneine, lovastatin, carotenoids and a suite of minerals, time is money. The team compared four solid media, Sabouraud’s dextrose agar, potato dextrose agar, corn meal agar and Richard’s synthetic agar, measuring mycelial diameter every three days over three weeks of incubation at 25 degrees Celsius.

Sabouraud’s dextrose agar emerged as the clear winner, producing the maximum mycelial growth of 54.0 millimeters after 21 days, ahead of potato dextrose agar, corn meal agar and Richard’s synthetic agar. But the researchers did not stop there. Knowing that the carbon-to-nitrogen ratio strongly influences mycelial growth in this species, they supplemented the best medium with malt extract, a rich carbon source, and yeast extract, a rich nitrogen source. Malt extract at 6 grams per liter pushed the colony diameter to 70.30 millimeters, but adding more than that brought no further gain. The decisive step came with yeast extract: the optimal combination of 6 grams per liter malt extract and 4 grams per liter yeast extract produced the maximum diameter of 84.60 millimeters after just 17 days of incubation, roughly ten days faster than unsupplemented Sabouraud’s medium.

Faster mycelium is only half the battle; producing the fruiting bodies, or stromata, that contain the medically interesting compounds requires moving the fungus onto solid substrates. Here the team prepared liquid inoculum in two nutrient broths of differing sugar and nitrogen composition, agitating flasks on a shaker at 170 revolutions per minute for up to eight days. Broth I, based on dextrose with peptone and yeast extract plus magnesium sulfate, potassium phosphate and vitamin B1, produced visible growth after seven days, five days sooner than broth II. The liquid mycelial culture also colonized grain substrates faster than mycelium grown on solid media, confirming that liquid spawn is the more efficient route to fruiting.

For the cultivation trials, the researchers chose four locally available and inexpensive grains: brown rice, white rice, corn kernels and wheat. Each 20-gram portion of grain received 45 milliliters of one of the two nutritional broths before sterilization and inoculation. Jars were incubated in darkness at 20 degrees Celsius and 65 to 70 percent relative humidity for the spawn run, then exposed to fluorescent light at 800 to 1,000 lux for twelve hours daily at 85 to 90 percent humidity to trigger primordia formation and stroma development. The logic of using local grains was deliberate: they are cheap, produced by regional farmers, and sustainable, reducing production costs for would-be growers in Jammu and Kashmir.

The results were unambiguous. Brown rice combined with nutritional broth I delivered the fastest performance on every measure: a spawn run of only 14 days, primordia after 11.5 days, and mature stromata after about 25.75 days, for a total cultivation cycle of 51.25 days from inoculation to harvest, the shortest of any combination tested. This substrate pairing also produced the longest stromata, at 78.0 millimeters on average, and the greatest number of stromata per jar, roughly 63 compared with a low of about 28 on wheat grain with broth II. Most strikingly, brown rice with broth I achieved a biological efficiency, the ratio of fresh yield to dry substrate weight, of 72.75 percent, far outperforming corn, white rice and wheat. Wheat grains did produce the thickest stromata, at just over 4 millimeters in diameter, but nowhere near the overall yield of brown rice.

The findings align with a growing international literature. Previous studies have found brown rice superior for C. militaris fruiting, reported maximum stroma yields on whole rice grains at slightly acidic pH, and shown that grain type and vitamin supplementation significantly shape mycelial growth and antioxidant capacity. Other work has optimized liquid culture conditions, identifying ideal glucose, yeast extract and mineral concentrations for biomass production. What distinguishes the Kashmir study is its focus on a wild, locally isolated strain rather than a commercial or imported one. Local strains may carry physiological adaptations to regional climate and substrates, and the authors argue that strain-specific optimization of this kind offers new insight into how cultivation protocols should be tailored to geographic origin rather than assumed universal.

The practical implications reach beyond mycology. C. militaris was approved by China’s Ministry of Public Health in 2009 as the first novel food of its kind, and its bioactive profile is considered comparable to that of the rare and costly caterpillar fungus Ophiocordyceps sinensis, making it a viable substitute in both traditional and modern therapeutic applications. Cordycepin and adenosine, its flagship compounds, show antibacterial, antioxidant, anti-inflammatory and anticancer activities in laboratory studies. By shortening the cultivation cycle, specifying cheap local substrates, and demonstrating conditions, 20 degrees Celsius, moderate humidity and a simple light regimen, that small facilities can maintain, the Kashmir team has laid a foundation for sustainable commercial cultivation that could benefit mushroom growers and entrepreneurs across the Indian Himalayas while easing pressure on wild populations.

Subject of Research: Optimization of nutrient media and grain substrates for the commercial cultivation of the wild medicinal fungus Cordyceps militaris from Jammu and Kashmir.

Article Title: Nutrient media and substrate optimization for commercial cultivation of Cordyceps militaris (L.) Fr., a novel medicinal mushroom from Jammu and Kashmir

Article References: Shrikhandia, P., Lone, S. A., Wani, A. H., & Bhat, M. Y. (2026). Nutrient media and substrate optimization for commercial cultivation of Cordyceps militaris (L.) Fr., a novel medicinal mushroom from Jammu and Kashmir. Discover Biotechnology, 3(1), Article 3. https://doi.org/10.1007/s44340-026-00048-z

Image Credits: AI Generated

DOI: 10.1007/s44340-026-00048-z

Keywords: Cordyceps militaris, medicinal mushroom, cultivation, substrate optimization, brown rice, cordycepin, mycelial growth, biological efficiency, Jammu and Kashmir, entomopathogenic fungus, Sabouraud dextrose agar, stroma formation

Mycorrhizal symbioses are among the oldest alliances in biology. Nearly all land-forming trees and plants rely on fungi that colonize their roots, extending the reach of the root system into the soil and trading minerals and water for sugars produced by photosynthesis. Ecologists divide these partnerships into broad functional groups. Arbuscular mycorrhizal fungi, often abbreviated AM, penetrate the cells of the root cortex and are ancient partners of flowering plants. Ectomycorrhizal fungi, by contrast, wrap themselves around root tips without penetrating cell walls and dominate among conifers and many trees of the oak, birch, and beech families. The two symbioses come with different nutritional economies: AM fungi are generally thought to be less selective foragers that deliver nitrogen-rich nutrients quickly, while ectomycorrhizal fungi excel at mining organic nitrogen directly from litter and soil organic matter. Which symbiosis dominates a forest therefore shapes how fast carbon cycles, how much carbon stays locked in soils, and which seedlings can establish beneath the canopy.

Because of these links to carbon and nutrient cycling, ecologists have long wanted to know whether the balance between mycorrhizal types is stable or whether it shifts with environmental change. Individual plots have shown responses to nitrogen pollution, drought, and warming, but evidence for a coherent, archipelago-wide reorganization has been scarce. The new analysis of forests across Japan provides exactly that: a broad-scale signal that the relative dominance of arbuscular mycorrhizal trees is changing along the length of the country, and that the change is not random.

The study’s central finding is that AM-associated trees are expanding their hold on Japanese forests, and that two explanatory threads run through the pattern. The first is disease. Tree diseases, driven by fungi, oomycetes, and insect vectors that thrive in a warming world, do not strike all tree species equally. Species that harbor ectomycorrhizal partnerships and species that harbor AM partnerships differ in their susceptibility, their rates of recovery, and their competitive ability following damage. When pathogens and pests remove or weaken particular canopy trees, the species that recruit into the gaps may disproportionately belong to the AM group, tipping the local balance and, cumulatively, the regional one. The second thread is climate warming itself. As temperatures rise, the climatic envelopes that once favored cool-adapted, ectomycorrhizal-rich forests in northern and montane Japan are shifting toward conditions that favor warm-adapted, AM-rich communities. Warming thus acts both directly, by altering which species can tolerate the local climate, and indirectly, by amplifying the diseases that thin the canopy.

What makes the result scientifically important is its breadth. Surveys and forest inventories distributed along the Japanese archipelago, which spans a remarkable gradient of climate from subtropical Ryukyu islands to boreal-influenced Hokkaido, revealed a coherent geographic pattern rather than a scatter of local anomalies. The archipelago functions in the study as a natural laboratory: because it is elongated along a latitudinal and thermal gradient, it allows researchers to ask whether the composition of forests is tracking climate in the way theory predicts. The answer is that it is, but with an added twist. The shift in mycorrhizal dominance is not simply a by-product of species moving poleward; it is entangled with the dynamics of disease, which can accelerate, redirect, or amplify the compositional change that warming alone would produce.

The mechanism by which disease and mycorrhizal type interact is an active area of research, and the Japanese findings add an important macroecological perspective to it. Mycorrhizal fungi do more than feed their hosts; they influence host defense, drought tolerance, and seedling survival. Ectomycorrhizal networks can support seedling establishment under parent trees, while AM associations often favor rapid growth and fast nutrient acquisition. A forest in which pathogens selectively remove ectomycorrhizal trees may therefore experience a cascade: fewer ectomycorrhizal adults mean fewer ectomycorrhizal propagules in the soil, less supportive fungal networks for the remaining regeneration, and an increasingly favorable environment for AM seedlings that thrive on disturbed, nutrient-flushed soils. Disease, in other words, can act as a ratchet, converting temporary losses into durable shifts in symbiotic identity.

Climate warming feeds this ratchet in several ways. Warmer winters fail to kill off insects and pathogens that cold once suppressed, extending their active seasons and geographic ranges. Warmer, sometimes drier summers stress trees, making them more vulnerable to attack. Extreme events such as typhoons, which regularly strike Japan, create large areas of disturbed forest in which fast-growing, disturbance-adapted species, many of them AM-associated, gain a foothold. Each of these processes has been documented in local studies; what the new research contributes is evidence that their combined effect is visible at the scale of the entire archipelago, registered in the shifting balance between mycorrhizal types.

The consequences of such a shift extend well beyond the identity of the trees themselves. Because AM and ectomycorrhizal forests differ in how they process nitrogen and store carbon, a wholesale conversion of forest symbiosis has implications for ecosystem function. Ectomycorrhizal-dominated forests are often associated with slower decomposition and greater storage of carbon in soil organic matter, partly because their fungi produce compounds that slow the breakdown of litter and because their nitrogen-mining strategy can suppress decomposer microbes. AM-dominated forests, in contrast, tend toward faster nutrient cycling, faster decomposition, and soils in which carbon is more exposed to microbial attack. A broad-scale transition from ectomycorrhizal toward AM dominance could therefore reduce the capacity of forest soils to lock away carbon, creating a feedback that adds to, rather than offsets, the warming that triggered the shift in the first place. The researchers emphasize that this is a hypothesis grounded in the established functional differences between the two symbioses, and that verifying the magnitude of any carbon feedback will require long-term monitoring of soils alongside vegetation.

There are also implications for biodiversity and forest management. The species that make up the AM and ectomycorrhizal pools differ in their economic and cultural value, in the wildlife they support, and in their responses to silvicultural treatment. Foresters in Japan have long managed stands of sugi, hinoki cypress, and other conifers, many of which rely on ectomycorrhizal partnerships, while broadleaved evergreens of the warm-temperate forests are predominantly AM-associated. A shift toward AM dominance would alter regeneration dynamics, the incidence of certain pests, and the suitability of land for different management objectives. Understanding the disease component of the shift gives managers an actionable lever: reducing pathogen spread, diversifying plantations, and protecting resistant genotypes could slow the conversion and buy time for adaptation.

The study also speaks to a growing recognition that global change operates through interactions rather than single causes. Warming alone would move species ranges; disease alone would reshape forests locally; but together, as the Japanese data show, they can produce a coordinated, archipelago-scale reorganization of one of the fundamental functional axes of forest ecosystems. For scientists modeling the future of the biosphere, the lesson is that predicting vegetation change requires tracking not only temperature and rainfall but also the health of the trees and the hidden fungal partnerships beneath their roots. For the forests of Japan, the finding is a warning and an opportunity in equal measure: the symbiotic identity of the woods is changing, and the window for understanding, anticipating, and perhaps guiding that change is open now, while the process is still measurable and, possibly, still manageable.

As monitoring continues, the Japanese archipelago will remain a bellwether. Its steep environmental gradients, rich forest flora, and dense long-term observational infrastructure make it one of the best places on Earth to watch the interplay of climate, disease, and symbiosis unfold in real time. The evidence assembled in this study indicates that the shift already underway is broad, structured, and driven by identifiable forces, and it establishes a baseline against which the forests of the coming decades will be judged.

Subject of Research: Climate warming and tree diseases driving a broad-scale shift in mycorrhizal tree dominance across Japanese forests

Article Title: Broad-scale shift in dominance of arbuscular mycorrhizal trees along the Japanese archipelago associated with tree diseases and climate warming

Article References: Schaefer, H., Yamashita, N., Hashimoto, S., Inagaki, Y., Kawanishi, A., Chatani, S., Shimadera, H., Furusawa, H., & Imaya, A. (2026). Broad-scale shift in dominance of arbuscular mycorrhizal trees along the Japanese archipelago associated with tree diseases and climate warming. Nature Communications. https://doi.org/10.1038/s41467-026-77711-w

Image Credits: AI Generated

DOI: 10.1038/s41467-026-77711-w

Keywords: arbuscular mycorrhiza, ectomycorrhizal fungi, Japanese forests, climate warming, tree diseases, forest ecology, mycorrhizal symbiosis, carbon cycling, soil fungi, forest composition, biogeography, Nature Communications

Orchids occupy a peculiar position in the plant world. Their seeds are among the smallest produced by any flowering plant, essentially dust-like grains that carry almost no nutritional reserves. In nature, an orchid seed cannot germinate at all unless it is first colonized by a compatible fungus, which supplies the developing embryo with carbon and other nutrients. Throughout the plant’s life, root-associated fungi continue to play critical roles in nutrient acquisition and stress tolerance. For epiphytic orchids, which perch high on branches with no direct connection to the soil, these fungal partners are not merely helpful; they are indispensable. Yet despite more than a century of scientific fascination with orchid mycorrhizas, the ecological rules governing which fungi colonize which orchids, and why those partnerships shift across landscapes, have remained remarkably opaque, especially in the species-rich tropics.

A research team from the Universidad Técnica Particular de Loja, led by Juan Pablo Suárez together with Stefania Cevallos and Paulo Herrera, set out to address this gap in one of the most orchid-divense regions on Earth. The southern Ecuadorian Andes host extraordinary concentrations of epiphytic orchids, compressed along elevational gradients so steep that a hiker can traverse dramatic shifts in temperature, humidity and vegetation within a single day’s walk. This natural laboratory allowed the researchers to ask a deceptively simple question with profound implications: what actually determines the composition of the fungal communities inside orchid roots? Is it the elevation at which the orchid grows, the specific site and its local microenvironment, or the identity of the orchid host itself?

To answer it, the team collected root samples from 699 individual orchid plants representing 11 species across elevational belts in the tropical montane forests of the region. This scale of sampling, covering hundreds of individual plants of many different host species along a continuous mountain gradient, is unusual in mycorrhizal ecology and gave the study its statistical power. From each root sample, the researchers extracted DNA and sequenced the internal transcribed spacer 2 region, a standard DNA barcode for fungi, using high-throughput amplicon sequencing. The approach allowed them to catalogue the entire community of fungi dwelling in each orchid’s roots, from genuine mycorrhizal partners to harmless or poorly understood endophytes.

The sequencing effort returned a striking total: 4,697 operational taxonomic units, or OTUs, essentially molecular proxies for fungal species, across the entire dataset. Within this diversity, the team identified 271 OTUs classified as putative orchid mycorrhizal fungi, the lineages known to form true nutritional symbioses with orchids. This rich catalogue provided the raw material for testing how fungal diversity and community composition change with elevation, among sites within the same elevational belt, and among host species.

One of the clearest patterns to emerge was a mid-elevation peak in fungal richness. The number of fungal OTUs associated with orchid roots was highest at intermediate elevations and declined toward higher elevations. Mid-elevation bulges in biodiversity have been documented for many groups of organisms in tropical mountains, but demonstrating the same pattern for root-associated fungi places these hidden symbionts within the same biogeographic framework as birds, plants and insects. The decline in fungal richness at the highest elevations suggests that increasingly harsh conditions, including lower temperatures, greater cloud immersion and reduced nutrient availability, act as an environmental filter, screening out fungal lineages that cannot tolerate them.

Beyond simple richness, the researchers examined how the identity of the fungal communities changed along the gradient. Community composition differed significantly among elevational belts, among sites within belts, and among host orchid species, confirming that all three factors matter. Importantly, the differences among elevations were driven primarily by species turnover rather than nestedness. In ecological terms, this means that as one moves up or down the mountain, fungal communities are not simply subsets of richer communities elsewhere; instead, entirely different suites of fungal taxa replace one another. Each elevational band harbors its own characteristic mycorrhizal partners, a pattern consistent with strong environmental sorting of fungal species along the gradient.

Yet within this turnover, the study uncovered a reassuring element of stability: the mycorrhizal assemblages maintained a persistent core across elevations. A set of widespread orchid-associated fungi appeared in roots sampled throughout the gradient, suggesting that some partnerships are robust to the environmental variation that reshuffles the rest of the community. This core persistence may be ecologically crucial. If a handful of reliable fungal generalists accompany orchids across the landscape, those fungi could serve as anchors for orchid establishment in new locations, while the more specialized, elevation-specific partners contribute to the fine-scale differentiation that makes each forest site unique. Site-level heterogeneity, the team found, contributed to this fine-scale differentiation, indicating that even within the same elevational belt, local differences in humidity, substrate, forest structure or disturbance leave measurable signatures in the root fungal communities of the orchids growing there.

The role of host identity adds another layer to the story. Even when growing side by side at the same elevation and site, different orchid species carried distinguishable fungal communities. This suggests that orchids are not passive recipients of whatever fungi happen to be drifting through the canopy; they exert some degree of selective control over their symbionts, a form of partner choice that has evolutionary as well as ecological significance. Taken together, the results indicate that fungal community assembly in epiphytic orchids is structured across multiple spatial scales simultaneously: broad elevational gradients set the regional template, local environmental conditions differentiate sites within that template, and host identity filters the fungi that ultimately take up residence in each root system.

The implications of these findings extend well beyond mycology. The authors note that the mid-elevation diversity peak and the stronger filtering observed at higher elevations indicate that orchid–fungus symbioses are highly sensitive to environmental gradients. This sensitivity has potential consequences for the stability of these partnerships under ongoing environmental change in tropical montane forests. Rising temperatures effectively shift elevational zones upsward, cloud bases lift, and rainfall patterns grow erratic. A mycorrhizal community finely tuned to a narrow elevational band may be unable to track its shifting habitat, particularly if the fungi involved have limited dispersal ability or narrow environmental tolerances. Because orchid germination depends absolutely on encountering compatible fungi, disruption of these symbioses could translate directly into recruitment failure for orchid populations, compounding the threats already posed by deforestation and illegal collection in one of the world’s biodiversity hotspots.

There is also a conservation planning dimension. If different elevational belts harbor different mycorrhizal communities through species turnover, then protecting a single elevational band cannot safeguard the full diversity of orchid–fungus partnerships across the landscape. Effective conservation of these epiphytic orchids, and the many other organisms that depend on intact montane forest canopies, will require protecting corridors that span complete elevational gradients, allowing both plants and their fungal partners to migrate as conditions change. The study’s demonstration of a persistent mycorrhizal core offers a note of hope, hinting that some partners may be flexible enough to accompany orchids through such transitions, but the turnover-driven architecture of these communities suggests that much of the symbiotic diversity is localized and, therefore, vulnerable.

The research, funded by Ecuador’s Secretaría de Educación Superior, Ciencia, Tecnología e Innovación, also highlights the value of studying symbioses in systems where environmental gradients are compressed into small geographic areas. Tropical montane forests, with their steep climatic gradients over short distances, function as natural experiments in community assembly, and the Ecuadorian Andes stand out as a global epicenter of epiphytic orchid diversity. By combining intensive field sampling across hundreds of individual plants with modern DNA sequencing, the Loja-based team has transformed a largely descriptive field into one capable of testing rigorous ecological hypotheses about how symbiotic communities are built.

As molecular tools become faster and cheaper, studies of this kind are likely to proliferate, revealing hidden dimensions of biodiversity that field surveys of visible organisms cannot capture. For now, this study stands as a detailed portrait of an invisible world beneath the bark and inside the roots: a world where thousands of fungal species sort themselves along mountainsides, where orchids choose and are chosen by their microbial partners, and where the delicate balance of these interactions may prove to be an early indicator of how tropical montane ecosystems respond to the pressures of the twenty-first century. What happens to the fungi in orchid roots, the work suggests, may ultimately shape what happens to the orchids themselves, and to the dazzling epiphytic communities that make tropical cloud forests among the most biologically rich places on the planet.

The study set out to address a persistent gap in inflammatory bowel disease research. While alterations in gut bacteria have been catalogued extensively in ulcerative colitis, the fungal microbiota, often called the mycobiota, has remained underexplored, partly because fungi make up such a tiny fraction of the gut’s microbial census. To quantify this minority population rigorously, the team took an approach that many microbiome studies neglect: rather than reporting relative percentages of microbial groups, which can be misleading when the total microbial load changes, they measured absolute numbers of fungal and bacterial genetic material in faecal samples using quantitative polymerase chain reaction techniques.

Specifically, the researchers amplified the ITS2 sequence, a segment of DNA in the fungal ribosomal RNA gene cluster that serves as a standard barcode for fungi, and the 16S ribosomal RNA gene, the workhorse marker for bacteria. By measuring gene copies per gram of faeces, they could compare true abundance rather than shifting proportions. This matters because if total microbial load changes during inflammation, relative abundance data alone can suggest differences that do not reflect real changes in absolute numbers, or mask genuine ones.

The study enrolled eighty-seven patients with ulcerative colitis and divided them into three groups according to disease activity. Twenty-nine patients were in long-standing remission, a group designated UClr. Twenty were in short remission, designated UCsr, meaning their disease had quieted more recently. And thirty-eight were experiencing an active flare, with samples collected at the onset of the flare before treatment changes could confound the picture. Critically, patients in the long and short remission groups provided two faecal samples over time, while flare patients provided one at flare onset, allowing the team to examine how microbial loads fluctuate within individuals across different disease states.

The headline result is striking for its sheer arithmetic. Across all patients, fungal ITS2 gene copies were dramatically outnumbered by bacterial 16S copies, with a median of roughly 927,000 fungal gene copies per gram of faeces against approximately 428 billion bacterial copies. That yields a fungal-to-bacterial ratio of about one to 461,000, a vivid reminder that even a substantial expansion of the gut’s fungal population involves organisms that remain vanishingly rare compared with bacteria. Yet the small size of this population did not make it inert.

When the researchers compared across disease states, fungal abundance was significantly higher in patients during flares than in those in long remission, a difference that held up statistically with a p-value of 0.0026. The comparison with the short remission group did not reach significance, hinting that fungal dynamics may be tied to the timing and durability of disease quiescence rather than simply to the presence or absence of inflammation. Perhaps the most informative measure was the ratio of fungal to bacterial gene copies itself. Because bacterial numbers held steady across all groups, the ITS2 to 16S ratio effectively isolates the fungal signal. That ratio was significantly elevated in flare patients compared with both remission groups, with p-values below 0.01, suggesting a specific expansion of the fungal compartment during active disease rather than a general microbial shift.

The longitudinal data added a further layer. Among patients followed with repeated samples, fungal abundance proved considerably more variable over time than bacterial abundance, which remained stable. Within this fluctuation, the researchers documented a modest but statistically significant decrease in the fungal-to-bacterial ratio at eight weeks, with a p-value of 0.029, indicating that the mycobiota responds dynamically, and relatively quickly, to changes in the patient’s condition.

What these findings mean mechanistically remains an open question, and the authors are careful to frame the work as describing an association rather than proving causation. Several possibilities merit consideration. Fungal overgrowth could be a consequence of the intestinal environment during flares. Inflammation disrupts the mucosal barrier and changes the availability of oxygen and nutrients in the lumen, conditions that may favour fungal proliferation. Antibiotic use, altered mucus production and shifts in immune tone could also open ecological space for fungi. Alternatively, fungi could act as drivers of inflammation. The immune system recognises fungal cell wall components through pattern recognition receptors such as dectin-1 and the inflammasome, and increased fungal burden might amplify inflammatory signalling in a gut already primed for flare-ups.

The distinction between long and short remission groups introduces another intriguing dimension. The fact that flare patients differed significantly from those in long remission but not from those in short remission raises the possibility that the mycobiota settles into a more stable, restrained state only after remission has persisted for some time. If confirmed, this could suggest that fungal surveillance or antifungal interventions might be most relevant in the vulnerable early period after an episode of active disease, when the risk of relapse is highest.

The study’s methodological choices strengthen its conclusions. Absolute quantification is a deliberate corrective to the relative-abundance framework that dominates much microbiome sequencing work. In a fungal population numbering in the hundreds of thousands of copies per gram against a bacterial population in the hundreds of billions, subtle but real shifts in fungal load could easily disappear in percentage-based analyses or, conversely, appear exaggerated. By anchoring their measurements in absolute gene copy numbers, the Barcelona team has produced data that can be directly compared across future studies and, ultimately, translated into potential clinical markers.

The clinical implications are tantalising but preliminary. If elevated fungal burden proves to be a reliable accompaniment of flares, faecal ITS2 quantification could conceivably join the toolkit of biomarkers used to monitor ulcerative colitis, complementing established measures such as faecal calprotectin. More ambitiously, the findings invite speculation about antifungal or probiotic strategies that specifically target the mycobiota, or about dietary and pharmacological approaches that suppress fungal expansion during high-risk periods. But the authors themselves emphasise that association is not causation, and that the next step is deliberate investigation of inter-kingdom microbial relationships in inflammatory bowel disease, work that would determine whether fungi are passive beneficiaries of an inflamed gut or active contributors to the inflammatory cascade.

Ulcerative colitis affects millions of people worldwide, and its relapsing-remitting course means that predicting and preventing flares is one of the central challenges of patient care. The gut microbiome has been a fertile hunting ground for answers, but research has been overwhelmingly bacterial in focus. This study reframes the picture. In a disease of the intestinal lining, the rarest members of the microbial community, present at ratios of one in nearly half a million, may nonetheless carry information about disease state that the bacterial majority does not. The fungal microbiota, long a footnote in gut microbiome research, is now demonstrably part of the story, and its dynamics across the arc of disease activity deserve sustained scientific attention.

The research, conducted without external financial support and approved by the Clinical Research Ethics Committee of Hospital Universitari Vall d’Hebron, was published as an open access article, ensuring that patients, clinicians and researchers worldwide can examine the data in full. As the field moves from cataloguing who lives in the gut toward understanding how entire microbial ecosystems behave during disease, studies like this one make clear that ecosystems include more than bacteria, and that the smallest voices in the community may speak loudest when disease strikes.

The research team, led by Rachna Jain together with Dipanjali Majumdar and Subhendu Chakraborty, collected house dust samples from multiple sites within non-compartmentalized, poorly ventilated dwellings, the kind of single-room living spaces where cooking, sleeping, and daily life all occur in the same air volume. The sampling strategy reflected the reality of slum housing, where there are no separate kitchens or bedrooms and where indoor conditions are governed almost entirely by outdoor climate, cooking fuel use, and household hygiene practices. Dust, in such environments, is not simply tracked in from outside; it accumulates continuously from a combination of road-side sources, indoor combustion, building materials, and biological growth encouraged by persistent humidity.

To characterize the fungal component of this dust, the team employed the spread plate method, a classical microbiological technique in which diluted dust suspensions are distributed across the surface of nutrient agar so that individual fungal colonies can be counted and isolated. Each isolate was then examined microscopically following lactophenol-cotton blue staining, a standard preparation that renders fungal structures such as conidiophores, phialides, and spore chains visible under the light microscope. Where morphology alone was inconclusive, the researchers used slide culture techniques, growing fungi directly on a thin agar block sandwiched between a slide and coverslip so that the delicate architecture of spore-bearing structures could be observed intact.

Five dominant fungal taxa emerged from this survey and were taken forward for molecular characterization, in which portions of the fungal genome were sequenced and the resulting sequences deposited in the NCBI GenBank database. The identified species included Aspergillus sydowii, Trichoderma longibrachiatum, Cladosporium sp., Neurospora sp., and Aspergillus nomiae. This roster is significant for several reasons. Aspergillus species are among the most clinically important indoor molds worldwide, capable of triggering allergic responses, asthma exacerbation, and, in immunocompromised individuals, invasive infection. Trichoderma longibrachiatum has been associated with opportunistic infections and is a frequent colonizer of damp building materials, while Cladosporium is one of the most ubiquitous allergenic genera in indoor environments globally. The presence of Neurospora, a rapidly growing mold often associated with burned or heat-treated organic material, hints at the influence of indoor cooking practices on fungal community composition.

Statistical analysis of the fungal data revealed a striking spatial uniformity. There was no significant difference in total fungal load between the sampled sites, suggesting that within these settlements the indoor environment functions as a relatively homogeneous exposure landscape. However, fungal diversity correlated positively with environmental variables including temperature, humidity, ventilation, indoor cooking, and hygiene practices. The diversity indices told a consistent story: both the Simpson index and Shannon Equitability exceeded 0.9, and the Shannon Index reached approximately 1.7, indicating an evenly distributed fungal community rather than one dominated by a single opportunistic species. This evenness matters from a health perspective, because residents are not merely exposed to one type of mold in high quantities but to a broad portfolio of biologically active species, each with its own allergenic, toxigenic, or infectious potential.

Alongside the biological characterization, the team quantified toxic metals in the same dust samples and translated measured concentrations into human exposure estimates using established risk assessment methodology. The exposure pathway analysis produced a clear hierarchy: ingestion of dust particles, driven by hand-to-mouth contact and the consumption of contaminated food and water handled in dusty environments, dominates over dermal absorption, which in turn exceeds inhalation of resuspended particles. This ordering is consistent with the standard EPA-style exposure model for house dust, but it takes on particular weight in slum households, where floor-level living, limited handwashing facilities, and the constant presence of young children on dust-contaminated surfaces amplify ingestion rates dramatically compared with formal housing.

The health risk calculations that followed delivered the study’s most alarming findings. The non-cancer hazard index, which aggregates the contributions of individual toxic elements across exposure routes, remained below the threshold value of 1 for adults, indicating that hazardous effects from chronic non-cancer endpoints are not expected for the adult population. For children, however, the hazard index exceeded 1, signaling a significant non-cancer health hazard even in circumstances where adults might remain below the danger line. The reasons for this discrepancy are physiological as much as environmental: children breathe more air, ingest more dust, and absorb more contaminant per unit of body weight than adults, and their developing organ systems are more vulnerable to the neurotoxic and nephrotoxic effects of metals such as lead, cadmium, and chromium.

Cancer risk estimates painted an even starker picture. For three toxic elements, cadmium, chromium, and nickel, the calculated lifetime cancer risk from household dust exposure was estimated to be significantly higher than the widely accepted regulatory limit of one in a million. Cadmium is a known human carcinogen associated with renal dysfunction and lung cancer, hexavalent chromium is one of the most potent occupational carcinogens recognized in toxicology, and nickel compounds are similarly classified as carcinogenic. That these three metals co-occur in household dust at levels capable of producing cumulative cancer risks above the acceptable threshold underscores the degree to which slum homes act as sinks for urban industrial and traffic-related pollution. Metals deposited on streets and roofs by vehicular emissions and industrial activity are resuspended, tracked indoors on footwear and clothing, and then concentrated in the settled dust that residents contact continuously.

The integration of fungal and chemical data within a single assessment framework is what distinguishes this work from much of the existing literature. Previous studies have typically addressed indoor mycobiota and indoor metal contamination as separate research questions, using different sampling campaigns, different analytical pipelines, and different risk models. Yet residents experience these hazards simultaneously, and there are plausible interactions between them: fungal spores and hyphal fragments can bind metal ions on their surfaces, metals can alter fungal community composition by exerting selective pressure, and the damp conditions that favor fungal proliferation may also influence metal speciation and bioavailability. By modeling both hazard classes together, the researchers have moved toward a cumulative exposure paradigm that more faithfully represents the real conditions under which slum dwellers live.

The authors argue that their findings carry direct implications for urban health policy. Indoor dust fungi, they suggest, should be recognized as overlooked emerging contaminants alongside the toxic elements that co-inhabit the same dust matrix, and both warrant regulatory attention and targeted interventions. Such interventions could include improved ventilation design in low-cost housing, promotion of hygienic cooking practices, dampness control, regular safe cleaning of floors and surfaces, and reduction of outdoor metal sources at the neighborhood level. Given that roughly a billion people worldwide live in informal settlements, and that climate change is expected to increase humidity and heat stress across the tropics, the conditions documented in this study are likely to become more, not less, common in the decades ahead.

The study also contributes to a growing scientific conversation about the indoor microbiome and its health consequences. Earlier research has shown that fungal diversity in house dust can influence childhood asthma development, with low diversity in some contexts associated with higher asthma risk, and that indoor fungal communities are strongly shaped by outdoor air and by dispersal limitation at short distances. The new findings extend this literature into an understudied setting, the tropical slum household, where the combination of near-permanent warmth, high humidity, dense occupation, and indoor biomass or solid fuel cooking creates an environment fundamentally different from the temperate, mechanically ventilated homes in which most indoor air research has historically been conducted.

Ultimately, the message of this research is that the air and surfaces of the world’s poorest homes harbor a compound burden of chemical and biological hazards that current regulatory frameworks barely capture. A hazard index above 1 for children and cancer risks exceeding one in a million from cadmium, chromium, and nickel in household dust are not abstract statistical outcomes; they represent quantifiable contributions to the excess burden of respiratory disease, developmental harm, and cancer borne by informal settlement residents. Making household dust a monitored, managed, and mitigated exposure medium, the study concludes, is a necessary step toward safeguarding the vulnerable populations who, quite literally, live on top of the problem.

The research team, working through dermatology clinics affiliated with the Diagnostic Center of Skin Diseases in Babol, recruited patients over the course of one year whose clinical presentations suggested acute fungal skin infection but whose cultures did not grow dermatophytes. All confirmed dermatophyte cultures were deliberately excluded, sharpening the study’s focus on the neglected remainder of the fungal world. In total, 25 patients were enrolled, each of whom provided written informed consent under an ethics approval from Babol University of Medical Sciences. Before sampling, instruments were disinfected with ethanol and heat-sterilized, and the patients’ skin and nails were swabbed with alcohol to minimize contamination, after which skin and nail scrapings were collected under sterile conditions for laboratory analysis.

The diagnostic pipeline began with the classical tools of medical mycology. Skin scrapings were examined directly under the microscope after treatment with 10 percent potassium hydroxide, a reagent that dissolves keratin and reveals fungal elements, while nail samples required a stronger 30 percent concentration. Under magnification, the preparations revealed the telltale fingerprints of invasion: septate hyphae threading through skin cells, and in some nail specimens, yeast cells, germ tubes, and pseudohyphae. Samples were then inoculated onto Sabouraud Dextrose Agar supplemented with chloramphenicol to suppress bacteria, and in parallel onto the same medium with the addition of cycloheximide, which inhibits many saprophytic fungi. Plates were incubated at 28 degrees Celsius for up to four weeks and inspected daily as colonies emerged, with each isolate characterized by colony color, texture, shape, margin, and growth rate.

Morphology alone, however, proved insufficient for definitive species identification—a limitation that lies at the heart of the study’s message. The researchers therefore turned to slide culture techniques on Potato Dextrose Agar to examine spore-producing structures under lactophenol aniline blue staining, and then took the decisive extra step of molecular characterization. Fungal DNA was extracted using a phenol-chloroform method, and the internal transcribed spacer region—spanning ITS1, the 5.8S ribosomal DNA, and ITS4—was amplified by polymerase chain reaction with standard primers. The resulting PCR products were verified on agarose gels, purified, sequenced, aligned, and deposited in GenBank under accession numbers before being compared against reference strain databases, with similarity thresholds above 99 percent accepted for species-level assignment.

The demographic profile of the 25 patients revealed a pronounced female predominance: 72 percent of cases were women, compared with 28 percent men. Ages ranged from 26 to 82 years, with a mean of 52.2 years and a median of 52, indicating that these infections do not confine themselves to any single life stage. The researchers speculate that hormonal influences, differences in skin physiology, hygiene practices, and exposure to cosmetics or skincare products that can create microenvironments favorable to fungal overgrowth may contribute to the sex disparity, though they caution that larger studies will be needed to disentangle these factors.

Clinically, the infections were as varied as the fungi behind them. Itching was the dominant complaint, present in 84 percent of patients, followed by erythema in 64 percent and scaling in 60 percent. The feet, nails, and groin were the most frequently affected sites, each involved in four cases, while other lesions appeared on the axillae, forearms, nose, hands, knees, buttocks, chest folds, and genital skin. The duration of symptoms ranged remarkably widely—from as little as fifteen days to as long as fifteen years—with a mean of about sixteen months but a median of only six, reflecting a mix of acute presentations and long-neglected chronic disease. Several patients reported relatives with similar symptoms, hinting at familial transmission or shared environmental exposure, and some had regularly used public gyms and swimming pools, environments well known for facilitating fungal spread.

The mycological results drove home just how crowded the field of potential skin pathogens has become. Candida albicans was the most frequent isolate, recovered from four patients, but it was only the beginning. The team also identified Candida parapsilosis, Candida catenulata, Cutaneotrichosporon dermatis, Nakaseomyces glabratus, Rhodotorula mucilaginosa, Rhodotorula macerans, Sporobolomyces roseus, Bullera alba, and Trichosporon asahii among the yeasts, alongside molds including Epicoccum nigrum, Sarocladium strictum, Aspergillus phoenicis, and Penicillium chrysogenum. Many of these organisms are better known as environmental saprophytes—residents of soil, decaying vegetation, and even food—and several, including the carotenoid-pigmented Rhodotorula species and the basidiomycetous yeasts Sporobolomyces and Bullera, are rarely considered primary agents of skin disease.

The presence of such organisms in genuine lesions rather than as casual contaminants raises important questions about opportunism and host vulnerability. Opportunistic fungi typically establish infection only when they accidentally breach injured skin or when host defenses are weakened, and several patients in the cohort carried conditions consistent with that model, including type 2 diabetes, hypertension, rheumatoid arthritis, hypothyroidism, and a history of coronary artery bypass grafting. Antibiotic administration, immunosuppression, and disruptions of the normal skin microbiome are all recognized to elevate the risk of cutaneous candidiasis, and analogous mechanisms may underlie infections caused by the more obscure molds and basidiomycetous yeasts recovered here.

What makes this fungal diversity more than a taxonomic curiosity is its direct bearing on treatment. Infections caused by yeasts and molds often present with clinical features that closely mimic dermatophyte infections—and, notably, lesions produced by filamentous fungi are nearly impossible to tell apart from those produced by yeasts, and even different yeast genera produce essentially identical pictures. A clinician treating on visual impression alone may reach for an antifungal agent optimized for dermatophytes while the actual culprit, a Candida species or an Aspergillus relative, responds poorly or not at all. Distinct fungal species carry distinct antifungal susceptibility profiles, and inaccurate identification paired with the wrong drug can produce suboptimal responses, recurrent infection, chronic disease, prolonged suffering, and escalating treatment costs.

Even the laboratory’s traditional toolkit has blind spots. Many yeasts form colonies so morphologically similar in culture that they cannot be distinguished on macroscopic appearance, and sometimes not even on basic microscopy; certain molds display the same problem. This is precisely where DNA sequencing changes the game. By reading the genetic barcode of the fungal isolate, molecular methods can assign a species identity with precision even when culture and morphology are misleading. The study’s authors argue, on the basis of the enhanced sensitivity and specificity demonstrated for molecular detection across multiple investigations, that the most reliable diagnostic strategy combines direct microscopy, culture, and PCR-based identification rather than relying on any single technique.

The Babol findings arrive amid growing international evidence that the epidemiology of superficial fungal disease is shifting. The frequency and distribution of causative agents vary significantly with geography, migration patterns, climate, socioeconomic status, lifestyle, and cultural practices, and surveys from Ethiopia to Poland to Hangzhou, China, have documented non-dermatophyte molds increasingly dominating some case series, particularly in onychomycosis. Against this backdrop, a single-center study of 25 patients might seem modest, and the researchers themselves acknowledge that the constrained sample size limits generalizability, calling for larger multicenter investigations to map the epidemiology and etiology of non-dermatophyte dermatomycoses more comprehensively.

Yet the central conclusion stands on firm ground regardless of sample size: non-dermatophyte cutaneous mycoses are real, diverse, and diagnostically treacherous, and even experienced microscopists and mycologists must guard against dismissing unusual isolates as colonization or contamination. The study’s authors emphasize that raising clinician awareness of the wide spectrum of possible pathogens—and ensuring access to precise mycological diagnosis, including molecular identification where conventional methods fall short—is vital for effective patient treatment. As sequencing technology becomes faster and more affordable, the era in which a fungal skin infection could be treated on appearance alone is drawing to a close, replaced by a more exacting but ultimately far more effective paradigm: identify the organism first, then choose the weapon.

Orchids occupy a peculiar place in the plant kingdom. With more than 28,000 species across 763 genera, the Orchidaceae is the most diverse family of flowering plants on Earth, yet its members are among the most difficult to propagate. Orchid seeds are dust-like and devoid of nutrient reserves, meaning that in nature, germination depends entirely on symbiotic relationships with fungi that supply the developing embryo with sugars, vitamins, and hormonal cues. Even after germination, orchids exhibit slow growth, prolonged juvenile phases, and limited early photosynthetic capacity. The embryo first develops into a protocorm, a specialized juvenile structure that precedes the differentiation of shoots and roots, and this delicate stage is where most natural propagation fails. As habitat loss and overharvesting push species like Vanda tessellata toward the brink, scientists have increasingly looked to the orchid microbiome for solutions.

Vanda tessellata itself carries considerable stakes. The species is widely used in Ayurvedic and Unani medicine for treating inflammatory, neurological, and respiratory disorders, and its ethnopharmacological value has made it a target of intense collection pressure. Despite prior reports of endophytic fungi from various orchid species, no previous study had systematically investigated the endophytic fungal diversity of V. tessellata or evaluated whether those fungi possess traits useful for plant growth promotion. The Kerala team, led by Parvathi Rajeevan of the Department of Biotechnology under the supervision of Shiburaj Sugathan, set out to close that gap with a study combining field collection, microbiology, molecular taxonomy, and plant physiology.

The researchers collected ten healthy V. tessellata plants from naturally growing populations on roadside trees at Parassuvakkal in Kerala, India, working under a permit from the Kerala Forest Department. From surface-sterilized root, leaf, and flower tissues, 1,050 tissue segments were processed, yielding an impressive 795 endophytic fungal isolates. Six morphologically distinct representatives were then screened for plant growth-promoting traits. The isolation protocol was rigorous: tissues were sterilized with 0.2 percent sodium hypochlorite for thirty minutes, dipped in 75 percent ethanol, rinsed repeatedly in sterile water, and imprinted onto fungal isolation medium to confirm that surface contaminants had been eliminated before incubation at 28 degrees Celsius in darkness.

When the six isolates were tested, one strain stood out decisively. KU/BOT/VT004 produced the highest levels of indole-3-acetic acid, the principal naturally occurring auxin, at 35.05 micrograms per milliliter when grown in Czapek’s Dox broth supplemented with L-tryptophan. The consistent enhancement of IAA production in precursor-supplemented cultures confirmed that these fungi synthesize auxin primarily through the tryptophan-dependent pathway, the same route exploited by many beneficial plant-associated microbes. Auxin matters enormously for orchids because it governs root differentiation, cell elongation, and tissue expansion, precisely the developmental processes that must succeed for a protocorm to become a viable plantlet. The other isolates showed moderate to minimal auxin output, underscoring pronounced strain-specific variation in biosynthetic capacity.

The strain’s metabolic repertoire did not end with auxin. Quantitative assays using Nessler’s reagent showed that KU/BOT/VT004 also produced the most ammonia among the six isolates, at 2.84 micrograms per milliliter, a trait associated with supplying readily assimilable nitrogen to plant hosts. On Chrome Azurol S agar prepared with King’s B medium, the isolate generated the largest siderophore halo, measuring 43.67 millimeters in diameter, indicating vigorous secretion of iron-chelating compounds. Siderophores mobilize ferric iron, an essential cofactor for chlorophyll biosynthesis and photosynthetic electron transport, and their abundance in the fungal secretome offers a mechanistic explanation for the greening effect later observed in treated seedlings. In dual-culture assays, the fungus also suppressed the radial growth of Fusarium oxysporum, a notorious wilt pathogen, by 44.6 percent, hinting at bioprotective value in addition to growth promotion.

Identifying the fungus required converging lines of evidence. Microscopic examination with lactophenol cotton blue staining and a modified slide culture technique revealed hyaline, septate, branched hyphae bearing smooth-walled, cylindrical conidia measuring on average 30.3 micrometers in length and 4.9 micrometers in width, hallmarks of the genus Colletotrichum in the family Glomerellaceae. Scanning electron microscopy after glutaraldehyde fixation and gold sputter coating confirmed dense conidial production with well-defined morphology. Colony appearance shifted across five different culture media, from cottony white-grey growth on malt extract agar to compact colonies with strong reverse pink pigmentation on Sabouraud dextrose agar. Molecular identification relied on amplification and Sanger sequencing of the internal transcribed spacer region of ribosomal DNA using the universal primers ITS1 and ITS4. BLASTn comparison against GenBank and a Maximum Likelihood phylogenetic analysis in MEGA 11, employing the Jukes-Cantor model with 1,000 bootstrap replicates, placed the isolate closest to the type strain of C. cf. cobbittiense. Because ITS sequences alone do not always resolve species boundaries within the notoriously complex genus Colletotrichum, the authors conservatively appended the abbreviation “cf.” to the species name. The sequence was deposited in GenBank under accession PX861570, and the living culture was preserved in the National Fungal Culture Collection of India as NFCCI-6297.

The most striking results came from the functional plant assays. The team grew asymbiotically germinated V. tessellata protocorms on half-strength Murashige and Skoog medium supplemented with 10 percent cell-free fungal culture filtrate, obtained by passing ten-day-old cultures through a 0.22-micrometer filter to ensure that any observed effects derived from soluble metabolites rather than living fungus. After sixty days, filtrate-treated protocorms reached a fresh weight of 1.07 grams, nearly double the 0.57 grams recorded for protocorms on basal medium and ahead of a peptone-supplemented nutritional control at 0.96 grams. By ninety days, treated protocorms weighed 2.93 grams, more than twice the peptone control, and at 120 days they still led at 2.53 grams versus 2.00 grams. Equally telling was what happened to the controls: protocorms on basal half-strength medium showed no further biomass gain after sixty days, a clear sign of nutrient limitation, whereas filtrate-treated cultures kept growing. Chlorophyll analysis at sixty days, performed by acetone extraction and spectrophotometric readings at 645 and 663 nanometers, showed total chlorophyll of 9.42 milligrams per liter in treated plantlets against 8.32 in the peptone control and just 5.23 in basal medium, indicating enhanced pigment biosynthesis and photosynthetic potential. All comparisons were statistically significant, analyzed by analysis of variance followed by Tukey’s multiple comparison tests.

The implications of these findings extend well beyond a single orchid species. The genus Colletotrichum has long carried a reputation as a group of destructive plant pathogens, responsible for anthracnose diseases in countless crops, yet research in recent years has unveiled a spectrum of lifestyles within the genus ranging from pathogenic to mutualistic. The landmark example is Colletotrichum tofieldiae, shown in 2016 to confer phosphate-dependent fitness benefits on Arabidopsis roots. KU/BOT/VT004 adds to a growing roster of beneficial Colletotrichum endophytes and demonstrates that secreted fungal metabolites alone, without physical colonization, are sufficient to elicit substantial growth responses in orchid tissue. The authors are appropriately careful in their interpretations, noting that the study quantified metabolite production in culture rather than nitrogen assimilation or iron uptake in plant tissues, and that direct colonization dynamics remain unexplored. They also acknowledge that an uninoculated medium filtrate control was not included and that the specific bioactive compounds were not chemically characterized, leaving metabolomic profiling, HPLC analysis, colonization studies, and greenhouse validation as essential next steps before any practical deployment.

Even with those caveats, the work opens a tangible pathway toward conservation biotechnology. If the metabolites driving protocorm growth can be identified, reproduced, and standardized, they could be incorporated into tissue culture protocols that currently rely on synthetic hormones and nutrient cocktails, potentially improving the survival and vigor of laboratory-raised orchids destined for reintroduction into the wild. For a species like Vanda tessellata, threatened simultaneously by habitat destruction and medicinal overharvesting, a fungal ally capable of accelerating propagation could make the difference between continued decline and meaningful recovery. More broadly, the study reinforces a theme running through modern plant science: that the organisms living cryptically within plant tissues, often invisible and unnamed, may hold some of the most practical answers to the challenges of biodiversity conservation and sustainable cultivation. The quiet fungus inside a roadside orchid in Kerala, it turns out, has plenty to say.