A new landmark editorial launching Ocean Microbiology, an open-access journal dedicated to marine and aquatic microorganisms, argues that the field stands at a unique crossroads. The publication, authored by Ramiro Logares of the Institute of Marine Sciences in Barcelona, describes a golden age of marine microbial research, powered by an extraordinary convergence of technologies that have transformed what scientists can see and measure. Over the past two decades, high-throughput DNA sequencing, high-resolution imaging, microfluidics and single-cell technologies, advanced bioinformatics, autonomous monitoring systems, predictive modeling and new theoretical frameworks have together revealed the diversity and complexity of ocean microbes at unprecedented scales, opening windows onto a world that was almost entirely hidden a generation ago.

The technical achievements of this era have been stunning in their scope. Large-scale sequencing campaigns have uncovered millions of novel microbial genes, dramatically expanding understanding of the metabolic potential harbored in ocean waters—genes that hint at undiscovered biochemistries operating in every liter of seawater. Surveys of plankton across ocean basins have exposed the existence of a vast ‘rare biosphere,’ an enormous collection of low-abundance microbial taxa that nonetheless perform ecologically relevant roles in nutrient cycling and energy flow. Completely new lineages of microorganisms have been described, some of which are forcing biologists to redraw portions of the tree of life itself. And beneath the boundaries of species definitions, researchers are detecting a large but still overlooked diversity within microbial populations, revealing evolutionary dynamics occurring at fine genetic scales that classical methods could never resolve.

Equally transformative has been the growing appreciation of microbial ecology as a web of interactions rather than a roster of species. Scientists are now characterizing the myriad ecological relationships that sustain marine food webs and underpin ocean ecosystem functioning, including newly mapped interaction networks, syntrophic associations in which different microbes cooperate metabolically to complete chemical transformations neither could achieve alone, and symbioses that bind microorganisms to hosts ranging from corals to fish larvae. These interactions play key roles in ecosystem functioning and nutrient cycling, and their disruption—by warming, acidification or pollution—could cascade through marine ecosystems in ways scientists are only beginning to anticipate. The editorial emphasizes that unveiling these interaction networks is one of the central tasks facing the next generation of marine microbiologists.

But the same editorial does not celebrate unreservedly. It arrives at a moment when accelerating climate change, including ocean warming and acidification, together with other anthropogenic pressures such as pollution, is impacting marine ecosystems at an unprecedented pace. Because microbes mediate the biogeochemical reactions that determine how much carbon the ocean absorbs, how efficiently nutrients are recycled, and how productive fisheries will be, understanding how microbial communities respond and adapt to these pressures has become a matter of global urgency. The convergence of unprecedented technological capability with unprecedented environmental stress, the editorial argues, creates both opportunities and responsibilities for the marine microbiology community worldwide.

The technical toolkit for meeting that responsibility is maturing rapidly. Long-term ocean observatory programs now monitor microbial communities across years and decades, producing time series that can distinguish genuine trends in microbial abundance and composition from natural seasonal and interannual variability. When coupled with new predictive models—drawing on machine learning, ecosystem modeling and increasingly sophisticated representations of microbial metabolism—these observatories are expected to yield essential insights into how the ocean microbiome may be changing over time, and into its resistance, resilience, or potential fragility in the face of multiple simultaneous stressors. Such forecasting capability is exactly what policymakers and ocean managers will need as climate impacts intensify through the middle of the century.

Timing matters in another sense as well. The editorial notes that as the United Nations Decade of Ocean Science for Sustainable Development, running from 2021 to 2030, reaches its midpoint, advancing understanding of microbial responses to global change has become essential for forecasting the future health of the ocean. International frameworks like the Ocean Decade have elevated the microbiome from a specialist concern to a central pillar of ocean sustainability science, reflecting the recognition that no meaningful model of the future ocean can be built without representing the microbial processes that regulate it. The launch of a dedicated, open-access venue for the field is framed as part of this broader institutional shift toward treating ocean microbes as infrastructure of the biosphere.

The new journal is explicitly designed around the interdisciplinary character of modern marine microbiology. The editorial stresses that the field requires integration across scales: from molecular mechanisms inside single cells to ecosystem processes spanning whole basins, from tightly controlled laboratory experiments to global ocean observations gathered by ships, floats and satellites, and from micro- to macroecological perspectives. Accordingly, the journal welcomes research spanning microbial diversity, genomics and evolution; biogeochemical cycles and microbial metabolism; host–microbe interactions; microbial responses to global change; marine biotechnology and applied microbiology, including so-called blue biotechnology and nature-based solutions to societal challenges; methodological and theoretical advances; and microbial oceanography, including studies of large-scale ecological patterns across the ocean.

The applied dimension of the field deserves particular attention, because the same microbial capabilities that run the planet’s cycles also represent a resource for human society. Marine microbes are a reservoir of enzymes, natural products and metabolic pathways with potential uses in medicine, industry and environmental remediation. Nature-based solutions inspired by microbial processes—harnessing communities that degrade pollutants, cycle nutrients in aquaculture systems or buffer coastal ecosystems against climate impacts—form a growing frontier where fundamental ocean microbiology translates directly into tools for sustainability. The editorial signals that such translational research will sit alongside discovery-driven science in the new journal’s scope, reflecting the field’s expanding societal relevance.

The invitation to the community is broad. The editorial calls on marine microbiologists across all career stages, in every region of the world, to submit their research, contribute as reviewers and help shape a publication intended not merely to document progress but to influence the future direction of marine and aquatic microbial science. As Logares writes in closing, sitting by the ocean one wonders what new secrets it will unveil in the coming years. Given the pace of discovery, the accelerating pressures of global change, and the sheer scale of the microbial world that remains unexplored, that question may well define ocean science for the rest of the decade.

Subject of Research: The ocean microbiome and its role in Earth system functioning under global change

Article Title: The ocean microbiome on a changing planet

Article References: The ocean microbiome on a changing planet. (n.d.). https://doi.org/10.1186/s44375-025-00004-y

Image Credits: AI Generated

DOI: 10.1186/s44375-025-00004-y

Keywords: ocean microbiome, marine microbiology, climate change, biogeochemical cycles, rare biosphere, microbial genomics, ocean warming, ocean acidification, symbiosis, blue biotechnology, microbial ecology, Ocean Decade

In research published in BMC Genomics, Tomasz Grzyb, Małgorzata Wlaźlak and Justyna Szulc took six bacterial strains isolated from soils in post-maize cultivation fields and subjected them to a battery of genome-based species assignment methods. Their targets belonged to the order Caryophanales, a group that includes the enormously consequential genera Bacillus, Priestia and Paenibacillus, organisms used in agriculture, industry and biotechnology, and close relatives of dangerous pathogens. What they found was a taxonomic landscape riddled with contradiction: species boundaries that shift depending on which metric you trust, genomes that intermix across supposedly distinct species names, and a widely used identity threshold that may be significantly miscalibrated.

The team compared several complementary approaches. Average Nucleotide Identity, or ANI, was computed with two different tools, FastANI and skani, which estimate the overall similarity between two genomes by aligning shared DNA sequence. Digital DNA-DNA hybridization, dDDH, a computational descendant of the wet-laboratory hybridization experiments that once defined bacterial species, was calculated using formula 2. The researchers also employed tetranucleotide Z-score distance, TZMD, which measures differences in short-word DNA composition, and single-copy gene phylogenomics, reconstructing evolutionary trees from sets of genes present exactly once in each genome. Crucially, rather than comparing each strain against only its nearest named neighbors, the authors performed comprehensive pairwise comparisons among all available RefSeq genomes at both complete and chromosome assembly levels for each taxonomic neighborhood, an unusually thorough sweep designed to reveal the true structure of variation around each strain.

For two of the six strains, the answer came back clean. Both could be assigned without ambiguity, one to Bacillus subtilis and one to Bacillus licheniformis, with every ANI comparison against their respective species exceeding the conventional 95 percent threshold and with clear phylogenomic separation from neighboring taxa. These cases show that the classical framework still works when species boundaries are genuinely well separated. The complications began with the remaining four strains, each of which landed in a different taxonomic minefield.

Strain Bac2 fell within the Operational Group Bacillus amyloliquefaciens, and here the analysis documented what the authors call fundamental boundary inconsistency. ANI values measured between recognized species within this group exceeded the ANI values measured among genomes assigned to Bacillus amyloliquefaciens itself. In other words, genomes bearing different species names were more similar to each other than genomes carrying the same name, a direct inversion of what a coherent species concept requires. Single-copy gene phylogenomics confirmed the chaos, revealing extensive intermixing of named species across the tree. A name assigned under these conditions conveys little about evolutionary relatedness.

Strain zielonkawy was assigned to the Bacillus cereus sensu stricto genomospecies, but its placement highlighted a familiar and stubborn problem: the deep intermixing of Bacillus cereus sensu stricto and Bacillus thuringiensis. These two names describe bacteria with dramatically different ecological roles, one an opportunistic pathogen and the other an insecticidal biocontrol agent, yet their genomes remain so entangled that no genomic metric reliably separates them. The new data add one more well-documented instance to a debate that has persisted since whole genomes first became available.

The two remaining strains, assigned to Priestia megaterium and Paenibacillus amylolyticus, produced perhaps the most novel findings. Both ANI multi-comparison analysis and single-copy gene phylogenomics suggested possible species intermixing or mislabelling within the public reference databases themselves. To the authors’ knowledge, this is the first study to quantitatively document species delimitation problems between Priestia megaterium and Priestia aryabhattai, and between Paenibacillus amylolyticus and Paenibacillus xylanexedens. The Paenibacillus analysis carried the caveat of a small available sample size, but the Priestia result points to a quietly widespread issue: reference databases, which thousands of labs treat as ground truth, may contain genomes whose species labels do not survive close genomic scrutiny.

Beyond the individual assignments, the study delivers a quantitative contribution to the methodology of bacterial taxonomy itself. Concordance analysis between FastANI and dDDH formula 2 revealed a non-linear relationship, well described by a quadratic fit with an R-squared of 0.991. From this relationship, the researchers derived a striking number: the traditional 70 percent dDDH species threshold, inherited from the pre-genomic era of DNA reassociation experiments, corresponds not to the conventionally assumed 95 percent ANI but to approximately 96.16 percent ANI. In practical terms, dDDH formula 2 is the more conservative of the two metrics, meaning that genomes judged to be the same species by the 95 percent ANI rule could still fail the dDDH test. Laboratories relying on ANI alone may be lumping together organisms that a stricter standard would split.

The comparison between alignment-free and tree-based approaches added further nuance. Correlations between skani genomic distances and single-copy gene phylogenomic patristic distances, the branch-length distances separating genomes on the reconstructed trees, were high across all datasets, with R-squared values ranging from 0.900 to 0.997. Overall genomic structure, in other words, is consistent between methods. But Spearman rank correlations, while still strong, were consistently lower, at 0.780 to 0.916, indicating that the precise identity of a genome’s closest neighbors can shift depending on whether you measure raw sequence similarity or reconstructed evolutionary distance. For taxonomists deciding whether a strain belongs to one species or its nearest rival, that rank-order disagreement is exactly where decisions get made.

As a constructive response, the authors propose a complementary diagnostic tool: within- and between-species ANI multi-comparison analysis paired with PERMANOVA, a non-parametric statistical test for differences among groups, followed by post-hoc pairwise testing. The idea is to treat species boundaries not as a single threshold but as a statistical question: do the ANI distributions within a named species differ significantly from the distributions between it and its relatives? Applied alongside single-copy gene phylogenomics, this framework could flag boundary inconsistencies that single-threshold assignment silently passes over, giving taxonomists an explicit, reproducible way to test whether a species name still carves nature at its joints.

The broader significance of the work extends well beyond six soil isolates from Polish maize fields. The Caryophanales taxa examined here anchor industries from probiotics to pest control and include the closest relatives of the anthrax bacillus. If species boundaries in these groups are inconsistent, then everything built on top of those names, from safety assessments of biocontrol strains to regulatory definitions of pathogenic species, inherits the uncertainty. The study also lands amid an ongoing, sometimes contentious community effort to redefine prokaryotic species entirely, with competing proposals for genome-based circumscriptions. By showing that even gold-standard tools disagree at the margins, and that the canonical thresholds themselves encode hidden conservatism, the Lodz team’s results argue for pluralism: no single number can settle species questions in difficult groups, but a disciplined combination of metrics, statistics and phylogenetics can at least make the disagreements visible, quantifiable and, ultimately, resolvable.

Subject of Research: Genome-based species delimitation and taxonomic boundary evaluation in Caryophanales bacteria using ANI, dDDH and phylogenomics

Article Title: Challenges in Caryophanales species delimitation: comparative evaluation of genomic similarity metrics and phylogenomics based on six environmental strains

Article References: Grzyb, T., Wlaźlak, M., & Szulc, J. (2026). Challenges in Caryophanales species delimitation: comparative evaluation of genomic similarity metrics and phylogenomics based on six environmental strains. BMC Genomics. https://doi.org/10.1186/s12864-026-13320-7

Image Credits: AI Generated

DOI: 10.1186/s12864-026-13320-7

Keywords: Caryophanales, species delimitation, phylogenomics, Average Nucleotide Identity, digital DNA-DNA hybridization, Bacillus subtilis group, Bacillus cereus group, Priestia, Paenibacillus, bacterial taxonomy, BMC Genomics, environmental strains

Botrytis cinerea, the gray mold pathogen, is among the most formidable adversaries in agriculture. It infects more than 200 plant species, kills host cells by secreting toxic compounds, and breaches plant defenses using cell wall-degrading enzymes, resulting in substantial yield losses across crops worldwide. For mulberry, the cornerstone of the silk industry and a plant of significant medicinal value due to its rich secondary metabolites, current control strategies rely heavily on chemical fungicides such as thiophanate-methyl and on resistant cultivars, approaches that are costly, environmentally damaging, and increasingly limited in effectiveness. The search for sustainable alternatives has driven attention toward endophytes, the bacteria, fungi, and actinomycetes that colonize internal plant tissues and are sometimes described as a plant’s second genome.

The research team, led by Lixue Wang, Yixuan Zhang, Wanting Li, and colleagues at Zhejiang University and Southwest University, subjected ZJU_268 to a battery of technical characterizations. Electron microscopy revealed rod-shaped cells with wrinkled outer surfaces, a feature associated with surface adhesion and stress tolerance in Bacillus species. Because 16S rRNA gene sequences are too conserved to reliably separate closely related Bacillus species, the team turned to the gyrB gene, which showed 99.7 percent similarity to B. velezensis, and confirmed the identification with average nucleotide identity analysis. Whole-genome sequencing on PacBio and Illumina platforms showed a compact circular chromosome of 3.93 megabases with no plasmids, containing 3,748 protein-coding genes. Functional annotation revealed extensive machinery for carbohydrate utilization, amino acid metabolism, cofactor and vitamin biosynthesis, biofilm formation, and stress response, along with several strain-specific biosynthetic gene clusters predicted to encode secondary metabolites, including antimicrobial lipopeptides.

Perhaps the most striking technical demonstration involved tagging ZJU_268 with a green fluorescent protein and tracking its journey through mulberry seedlings. Confocal laser scanning microscopy showed that the bacterium established stable populations on root surfaces, penetrated internal tissues, spread through the cortex and vascular system, and eventually migrated upward into stems and leaves. Quantitative recovery of GFP-labeled colonies from homogenized tissues over 35 days confirmed that roots served as the primary reservoir while aerial tissues were colonized later and at lower densities, establishing ZJU_268 as a genuine systemic endophyte rather than a transient surface dweller.

In laboratory antagonism assays, ZJU_268 proved devastatingly effective against fungi. Inhibition rates against most Ascomycetous pathogens exceeded 85 percent, and mycelial growth of Botrytis cinerea was nearly eliminated, with an inhibition rate of 98.09 percent. Scanning electron micrographs showed treated hyphae distorted, folded, twisted, and locally swollen, in sharp contrast to the smooth, intact filaments of untreated controls. The antifungal activity emerged about nine hours after incubation, peaked at 24 hours, and remained chemically robust: the cell-free culture supernatant retained its potency after heating at temperatures up to 121°C and across a pH range from 2 to 10, indicating that the active compounds are unusually stable molecules.

The greenhouse results translated this potency into disease control. In sterilized soil, mulberry seedlings treated with ZJU_268 cell suspensions showed a disease incidence of 41.67 percent, and those treated with the cell-free supernatant 66.67 percent, compared with severe disease in untreated pathogen-challenged plants and 25.00 percent in the fungicide-treated positive control. Quantitative PCR confirmed that pathogen abundance in roots was significantly lower in both bacterial treatments. Critically, efficacy persisted in non-sterilized natural soil containing intact indigenous microbial communities, with control efficacies of 47.62 percent for the live bacterium and 28.57 percent for the supernatant. Growth promotion was equally dramatic: at an optimal dose of 10⁶ CFU/mL, treated seedlings showed increases of roughly 74 percent in root length, 81 percent in shoot length, 173 percent in total fresh weight, and 136 percent in total dry weight, while seed germination rates rose by up to 24 percent.

To understand how these effects arose, the researchers sequenced the root microbiome of treated plants using 16S rRNA and ITS amplicon profiling. Bacterial communities clustered distinctly between treated and control plants on Bray-Curtis ordination, whereas fungal communities shifted less in composition but changed markedly in their ecological structure: fungal co-occurrence networks lost connectivity, with fewer nodes linked and fewer positive associations, while bacterial network topology remained largely intact. Taxonomically, the treatments depleted several potentially harmful taxa, including the bacterial genera Pantoea, Afipia, and Rhizorhapis and the fungal genera Verruconis and Exobasidium, while enriching beneficial bacteria such as Streptomyces, Flavobacterium, Rhizobium, Pseudomonas, and Novosphingobium, and fungi including Cladosporium, Arthrobotrys, Meyerozyma, and Xenoacremonium. The team then cultured 223 bacterial and 42 fungal isolates from treated roots and validated their functions directly. Selected Pseudomonadaceae strains inhibited B. cinerea by 85 to 96 percent in dual cultures, reduced lesion sizes on detached mulberry leaves, and boosted seedling fresh weight and shoot height, while fungal isolates from the Cladosporiaceae and Nectriaceae families suppressed the pathogen by roughly 50 percent and promoted plant growth. Compatibility assays showed ZJU_268 could work synergistically with these enriched partners, suggesting a path toward engineered microbial consortia.

Metabolomics added the final layer of the mechanism. Untargeted liquid chromatography–mass spectrometry detected 3,431 metabolites in mulberry roots and identified 625 that changed significantly across treatments. Both the live bacterium and its supernatant elevated a suite of compounds, including the cytokinin trans-zeatin, thioinosine monophosphate, L-galactose, uridine, L-serine, and the fungicide carbendazim. When these purified metabolites were fed to representative enriched isolates in vitro, bacterial growth measured by optical density and fungal colony expansion both increased significantly. Tellingly, none of the same metabolites stimulated Botrytis cinerea; L-serine and uridine actually inhibited it. This selectivity suggests the root itself becomes a chemical gatekeeper, feeding friendly microbes while starving or repelling the pathogen. Quantitative PCR of plant genes supported this interpretation, with upregulation of CYP735A, consistent with zeatin accumulation, and of PSP and PAL, reflecting shifts in amino acid and phenylpropanoid metabolism. Live cells and supernatant also diverged in their metabolic signatures: the supernatant drove a large accumulation of ascorbate, an antioxidant buffer, whereas live colonization promoted dynamic turnover of ascorbate metabolism, hinting at complementary modes of protection, rapid chemical defense from secreted metabolites and sustained physiological reprogramming from an established endophyte.

The authors frame their findings at the level of the holobiont, the plant plus its microbial constellation, arguing that ZJU_268 functions less as a lone assassin of fungi and more as a microbiome architect, reshaping who lives in the root, rewiring interaction networks, and editing the chemical environment so that the resulting community suppresses disease and fuels growth. With its efficacy demonstrated in natural soil, its stability under heat and pH extremes, and its dual biocontrol and growth-promoting repertoire encoded on a single plasmid-free chromosome, ZJU_268 represents a promising candidate for biological products aimed at sustainable sericulture. For an industry seeking to cut pesticide use without sacrificing yield, a bacterium plucked from the roots of a tree that has stood for a thousand years may prove an unexpectedly modern ally.

The backdrop is one of the planet’s great carbon vaults. Mangrove ecosystems are recognized as major blue-carbon reservoirs, holding between 4.4 and 11.7 petagrams of organic carbon globally — billions of tonnes locked in waterlogged soils where oxygen is scarce and decay is slow. The Sundarban alone, sprawling across 3,629.57 square kilometers of delta, carries a carbon stock estimated at 26.62 teragrams, more than 26 million tonnes. But these reservoirs are under pressure. Rising salinity, shifting hydrology and intensifying human activity are reworking the microbial communities that underpin coastal food webs, including the microalgae and cyanobacteria that, though individually microscopic, collectively fix enormous quantities of carbon in shallow, sunlit waters and export it into the sediments below. As the composition of those communities changes, the researchers argue, identifying taxa that can keep fixing carbon under future conditions becomes a conservation question as much as a biotechnological one.

To find them, the team turned the mangrove inside out, genomically speaking. Rather than cataloguing which microbes were present by microscopy, they performed whole-genome metagenomic profiling of degraded mangrove soils — shotgun-sequencing the collective DNA of the sediment community and mapping the reads against known genes to reconstruct which metabolic machinery the ecosystem was actively deploying. Where older surveys relied on marker genes such as 16S ribosomal DNA to sketch community composition, whole-genome metagenomics captures the entire functional repertoire: every copy of every carbon-metabolism gene present in the sediment’s pooled genome library. The analysis surfaced six dominant microalgal taxa whose abundances tracked the prevailing salinity and nutrient stress, effectively flagging the organisms the environment itself had shortlisted. The logic is elegant: a degraded, saline, nutrient-fluctuating mudflat is a brutal natural selection chamber, and any microalga that thrives there already carries genetic equipment for osmotic tolerance and flexible carbon metabolism that laboratory strains bred in benign conditions may lack.

All six taxa were then isolated into pure cultures from the same habitats and subjected to a 16-day screening under ambient carbon-dioxide levels of roughly 420 parts per million — the concentration of today’s atmosphere. The investigators tracked two deceptively simple metrics: specific growth rate, the exponential pace at which cells divide, and biomass gain, the sheer quantity of organic material accumulated per liter. Three strains pulled clear of the field: Chlorella sp., a spherical green microalga long studied for biofuels; Limnospira platensis, the coiled filamentous cyanobacterium better known as spirulina; and Leptolyngbya boryana, a slender, sheathed cyanobacterium that forms soft mats in the wild. Each represents a different branch of the photosynthetic tree, which made their head-to-head comparison a genuine test of three distinct evolutionary strategies for grabbing carbon.

The finalists were then pushed up a carbon-dioxide ladder designed to mimic present and future atmospheres: 0.04 percent, 0.05 percent, 0.20 percent and 10 percent CO₂. The lower rungs track the world we inhabit and the near-term trajectory of rising emissions; 0.20 percent — twenty times today’s ambient level — probes the physiological limits of acclimation; and the 10 percent tier, roughly 100,000 parts per million, goes far beyond any plausible atmospheric scenario and approaches the CO₂ content of industrial exhaust streams. For microalgae, extra CO₂ is a double-edged gift: it supplies the limiting substrate for photosynthesis, but dissolved as carbonic acid it pushes culture pH downward, forcing cells to spend energy on pH regulation — a stressor documented in other Chlorella studies. The question, therefore, was not simply which microbe survives elevated CO₂, but which one converts the additional carbon into new cells rather than stalling.

Leptolyngbya boryana swept the board. It delivered the highest biomass yield of the three, at 1.31 grams per liter, the richest carbon content at 0.52 grams of carbon per gram of dry weight — meaning carbon comprised more than half of everything it built — and the steepest carbon-dioxide fixation rate, reaching 149 milligrams of CO₂ per liter per day. That last figure comes from the carbon balance of the culture: by measuring how much carbon ends up locked in harvested biomass, researchers back-calculate how much CO₂ must have been drawn from the gas phase to supply it. In practical terms, a cubic meter of dense L. boryana culture could in principle scrub on the order of 149 grams of CO₂ daily before any process optimization — a benchmark that matters enormously when engineers size photobioreactors for emissions treatment.

The deeper explanation lies in the microbe’s genes. Metagenomic analysis showed that L. boryana carried the strongest representation of two canonical carbon-fixation pathways among the isolates: the Calvin–Benson–Bassham, or CBB, cycle and the reductive tricarboxylic acid, or rTCA, cycle. The CBB cycle is photosynthesis’s carbon-grabbing engine: the enzyme RuBisCO attaches CO₂ to a five-carbon sugar, ribulose-1,5-bisphosphate, splitting it into three-carbon molecules that ATP and NADPH then reduce into sugars. The genes cbbL and cbbS encode the large catalytic and small structural subunits of that enzyme; gap2 encodes a glyceraldehyde-3-phosphate dehydrogenase that drives the cycle’s reduction step; and zwf, encoding glucose-6-phosphate dehydrogenase, feeds the oxidative pentose-phosphate pathway, generating reducing power and the sugar skeletons needed to regenerate RuBisCO’s substrate. The gene accC encodes the biotin-dependent carboxylase subunit of acetyl-CoA carboxylase, the committed first step that diverts fixed carbon into fatty-acid synthesis — an essentially irreversible carbon sink. Enrichment of rTCA machinery, a reversal of the Krebs cycle that incorporates CO₂ through reductive carboxylation reactions, suggests the organism carries layered, redundant routes for pulling inorganic carbon into biomass.

Why does a single hardy cyanobacterium warrant this attention? Because the dominant technologies for capturing carbon dioxide — chemical solvents, engineered membranes, solid sorbents — are energy-hungry and costly, and they merely concentrate the gas without converting it. Biological fixation is different: photosynthesis transforms CO₂ into living biomass that can, in principle, be harvested, processed into feeds, fertilizers or biofuel precursors, and removed from the atmospheric ledger. A saline-adapted strain sharpens that proposition. Coastal cultivation of L. boryana could run on seawater rather than scarce freshwater, sidestepping competition with agriculture, and could be co-located with coastal industries whose emissions supply the carbon. There is also a blue-carbon synergy to consider: biomass grown in coastal systems feeds carbon into the same sediment pools that make mangroves such formidable long-term stores. The team’s broader research program, including earlier reviews on harnessing microalgae for net-zero emissions and fieldwork tracking algal diversity as Sundarban mangroves are converted to rice paddies, frames such strains as both climate tools and barometers of ecosystem health.

The researchers are candid about the distance between flask and deployment. Laboratory cultures offer idealized light, temperature and mixing; open ponds and industrial bioreactors do not, and scale-up routinely collides with light limitation in dense cultures, contamination by grazers and rival microbes, and the energy cost of harvesting and dewatering soupy biomass. The study, which rests on Nayak’s doctoral research and was supported by India’s DST-INSPIRE Fellowship, the Department of Biotechnology, the National Innovations in Climate Resilient Agriculture program and an ICAR National Fellow project, provides the starting genotype and the genetic targets. The next steps it implies are familiar to the field: validating performance in outdoor saline cultures, quantifying fixation rates under real flue-gas compositions with their sulfur and nitrogen oxides, and potentially deploying genome-editing tools to push the expression of cbb and accessory genes even higher.

There is a quiet irony in the provenance of this strain. It was not found in a pristine sanctuary but in degraded mangrove soils — ecosystems already bent by salinity intrusion and human pressure. The very stressors that threaten the Sundarban’s carbon vault appear to have forged a microbe exceptionally well equipped to re-carbonize it. Whether Leptolyngbya boryana graduates from a discovery in 3 Biotech to an industrial carbon-capture workhorse remains to be seen, but the study makes a compelling case that the answer to an atmospheric problem may already be growing, patiently and photosynthetically, in the mud.

CycloneSEQ™ stands out for its reliance on long-read sequencing, which allows for the direct reading of DNA without the fragmentation typically associated with short-read sequences. This capability is particularly crucial, as many bacterial genomes contain repetitive regions and substantial GC content, factors that have historically hampered full-length genome assemblies. The performance assessment conducted by researchers at BGI-Research aimed to fill these gaps presents raw data alongside processed outputs, thus ensuring transparency and reproducibility in scientific inquiry. This publication in the open-science journal GigaByte marks a significant milestone in the pursuit of assembling complete genomes.

The benchmarking of CycloneSEQ™ was put to the test using Akkermansia muciniphila, a bacterial reference strain known for its importance in gut health. The evaluation yielded an impressive 12.07 Gbp of long-read data, presenting an average read length of 11.6 kbp. This hybrid approach, which combines the long-read capabilities of CycloneSEQ™ with the DNBSEQ™ short-read technology, achieved a complete assembly of the strain’s genome with an astonishingly low mismatch rate of less than 0.0001%. While traditional sequencing methods struggle with the complexities inherent in circular bacterial genomes, the CycloneSEQ™ platform has demonstrated that it can successfully navigate these challenges, producing reliable genomic assemblies with remarkable precision.

Moreover, this innovative sequencing technology was applied to a selection of ten bacterial strains isolated from human gut microbiota. Remarkably, researchers managed to close the genomes of all ten strains, including the additional circular structures of phages and plasmids that are frequently overlooked by conventional short-read sequencing. Through the employment of long-read only assemblies, complete genomes were constructed for eight out of the ten strains, marking a significant advancement over short-read-only methods, which failed to assemble any complete genomes from this selection.

Complex microbial communities also posed a testing ground for the CycloneSEQ™ platform. Through hybrid assembly techniques on a synthetic gut community consisting of 21 distinct microbial strains, researchers achieved five complete metagenome-assembled genomes (MAGs). This outsized performance contrast with both short-read and long-read methods underscores CycloneSEQ’s potential in unraveling the intricacies of microbial ecosystems, indicating its capability to handle diverse and complex samples that traditional approaches may falter upon.

The advantages of using long-read sequencing speak directly to its capacity for addressing the challenges of genome assembly. CycloneSEQ’s extended read lengths allow for the assembly of circular genomes, while DNBSEQ’s short-read technology supplements these assemblies by enhancing accuracy during the polishing phase. The ongoing research aims to explore additional non-synthetic samples, fine-tuning the integration between long and short reads in a bid to accelerate genome assembly while simultaneously ensuring quality.

An inherent challenge in microbiome studies has been the traditional methods’ limitations in resolving genomes from highly repetitive regions rich in GC content. CycloneSEQ™, with its direct sequencing approach that circumvents fragmentation issues, offers a solution to this long-standing problem. The study’s outcomes exemplify an evolving landscape in sequencing technology, one that effectively bridges the gaps left behind by the reliance on short-read methodologies.

As the field of genomics continues to advance, the implications of CycloneSEQ™ extend beyond mere sequencing capabilities. This platform not only aids in constructing accurate genomic representations but also adds layers of understanding to microbial functions and interactions within various environments. Its potential applications could reverberate through environmental monitoring, public health, and the development of novel therapeutic strategies targeting gut microbiota and other microbiomes.

The future landscape of sequencing technology is decidedly being reshaped by innovations such as CycloneSEQ™, and the scientific community stands at the precipice of a new era in which complete microbial genomes can be more routinely accessed and studied. The combination of extended read lengths, combined methodologies, and open access to data aligns with the increasingly collaborative nature of modern research, enhancing the capability for peer verification and scientific rigor.

As this technology matures and receives further validation through additional studies and comparative analyses, it is poised to pave the way for significant advancements in microbiology and genomics. Researchers are excited about the potential for CycloneSEQ™ to not only fill existing gaps in bacterial draft assemblies but also to enhance our understanding of microbial diversity, functionality, and evolutionary dynamics in a wide array of ecosystems.

In conclusion, CycloneSEQ™ represents a watershed moment in the field of genome sequencing, challenging the conventions established by earlier sequencing technologies. As researchers employ this advanced capability, the doors it opens for profound discoveries and advancements in microbial sciences are vast and promising.

Subject of Research: CycloneSEQ for Complete Bacterial Genomes
Article Title: Efficiently Constructing Complete Genomes with CycloneSEQ to Fill Gaps in Bacterial Draft Assemblies
News Publication Date: 25-Apr-2025
Web References: https://doi.org/10.1101/2024.09.05.611410
References: Hewei L, et al. Efficiently Constructing Complete Genomes with CycloneSEQ to Fill Gaps in Bacterial Draft Assemblies. GigaByte. 2025.
Image Credits: Hewei L, et al. Efficiently Constructing Complete Genomes with CycloneSEQ to Fill Gaps in Bacterial Draft Assemblies. GigaByte. 2025.

Keywords

Nanopore sequencing, Complete bacterial genomes, CycloneSEQ technology, Genome assembly, Hybrid sequencing methods, Microbial genomics, GigaScience, Long-read sequencing, DNBSEQ short-read technology, Gut microbiota.