The research team, led by Mengru Han and colleagues including senior author Baili Feng, selected two cultivars, Liuleng (black) and Ganqing10 (yellow), grown side by side in the same experimental plot of the Agricultural Science Research Institute of Gannan Tibetan Autonomous Prefecture. In previous work, the group had shown that black and yellow highland barley represent the extremes of compositional variation among colored cultivars, with black grains carrying roughly twice the flavonoids, phenolics, and anthocyanins of their yellow counterparts. The central question of the new study was whether those initial chemical differences would steer fermentation along fundamentally different trajectories, or whether the microbial communities driving the process would converge on a shared path regardless of raw material.

To find out, the researchers followed the traditional Tibetan brewing procedure. Barley grains were soaked, boiled, cooled, and inoculated with a starter combining indigenous Tibetan jiuqu—a traditional fermentation culture prepared from barley flour, plateau herbs, and aged starter—with high-activity dry yeast. The prepared grains then fermented in sealed earthenware jars at 29 degrees Celsius for 72 hours, with samples harvested at 0, 24, 48, and 72 hours. For each time point the team tracked antioxidant compound contents and radical-scavenging activities, sequenced bacterial 16S rRNA genes and fungal internal transcribed spacer regions to profile the microbiome, and used ultra-performance liquid chromatography coupled to tandem mass spectrometry to map the non-volatile metabolome at the final stage of fermentation.

The antioxidant measurements told a nuanced story. In both cultivars, fermentation pushed total phenolic content upward and anthocyanins peaked at 48 hours before easing slightly, while total flavonoid content declined progressively—suggesting that flavonoids were being transformed, deglycosylated, or converted into other phenolic derivatives rather than simply accumulating. Yellow barley showed the more dramatic relative gains, ultimately surpassing black barley in total phenolic content by the end of fermentation and posting a larger rise in total antioxidant capacity. Yet black barley never surrendered its lead in radical scavenging: it maintained consistently higher DPPH, ABTS, hydroxyl radical, and superoxide radical scavenging activities throughout all 72 hours, an advantage the authors attribute to its richer initial reserves of flavonoids, anthocyanins, and pigment-associated metabolites.

Microbial sequencing revealed a fermentation world that was simultaneously shared and distinct. In both jars, bacterial diversity fell steadily, and the fungal community collapsed toward near-total dominance by a single genus, Saccharomycopsis, whose competitive grip on carbohydrate utilization drove fungal diversity essentially to zero by the middle of fermentation. Among bacteria, Lactococcus flourished early, peaking at 24 hours, while Pediococcus rose steadily to dominate the late stage in both cultivars—an ecological succession that mirrors patterns seen in other cereal fermentations, where substrate consumption, acid accumulation, and falling pH progressively eliminate competitors and favor acid-tolerant lactic acid bacteria.

Beneath these broad similarities, however, the two cultivars hosted measurably different microbial worlds. Bacterial richness rose and then fell in black barley but followed the opposite pattern in yellow barley, and differences in alpha diversity were detectable even before fermentation began, hinting that the grains carried distinct resident microbiota shaped by their contrasting chemistry. LEfSe biomarker analysis identified cultivar- and stage-specific taxa: Gordonia and Frigoribacterium marked the 24-hour stage in black barley, Enterococcus marked 48 hours, and Levilactobacillus emerged at 72 hours, whereas yellow barley at 24 hours was characterized by Lactococcus and Flavobacterium. Principal coordinate analysis showed the overall bacterial community structures broadly overlapped, but the fungal communities differed significantly between cultivars, if modestly in magnitude.

Perhaps the most striking cultivar differences emerged from co-occurrence network analysis, which maps the statistical associations among microbial taxa. The yellow barley network was denser, more highly connected, and richer in positive correlations, suggesting a more cooperative, tightly interlinked community—the kind of structure that previous research has linked to efficient joint substrate utilization and metabolite exchange. The black barley network, by contrast, was more modular and compartmentalized, with taxa organized into relatively independent functional subgroups that may allow separate responses to acid stress, substrate availability, or phenolic inhibition. The putative keystone taxa also diverged sharply: Bacillus and Zoogloea anchored the black barley network, while Lactococcus, Enterococcus, and Aquabacterium held central positions in yellow barley. Predicted functional profiles from PICRUSt2 were broadly similar between cultivars—dominated by carbohydrate, amino acid, and energy metabolism—indicating a shared functional foundation, with differences concentrated in low-abundance pathways.

The metabolomics data sharpened the picture considerably. Principal component analysis and hierarchical clustering cleanly separated the fully fermented black and yellow samples, and while most detected metabolites were shared, black barley contained more cultivar-specific compounds. The metabolites enriched in black barley were overwhelmingly flavonoids and phenolic acids—derivatives of isoscoparin, tricin, chrysoeriol, caffeoyl compounds, and 1-acetyl-beta-carboline—and KEGG enrichment pointed squarely at flavonoid and anthocyanin biosynthesis pathways, including chrysoeriol aglycone, apigenin C-glycoside, and flavone and flavonol biosynthesis. Yellow barley, by contrast, accumulated more amino acids, small peptides, and their derivatives, suggesting its fermentation leaned more heavily toward primary nutrient transformation and the formation of taste-related compounds.

Correlation analyses then wove the three data layers together. Antioxidant indices were strongly and positively associated with specific flavonoid glycosides and phenolic derivatives: total flavonoid content tracked compounds such as chrysoeriol-7-O-rutinoside-5-O-glucoside and quercetin-5,4′-di-O-glucoside with correlation coefficients above 0.94, while anthocyanin content aligned with gallic acid and 1-acetyl-beta-carboline. Notably, the lactic acid bacterial genera Lactiplantibacillus and Levilactobacillus were the taxa most closely and positively correlated with antioxidant-related flavonoid and phenolic metabolites—a finding consistent with known β-glucosidase, esterase, and phenolic acid decarboxylase activities in some lactic acid bacteria that can liberate bound phenolics from grain matrices. Meanwhile, genera such as Aquabacterium, Bradyrhizobium, Lactococcus, and Microbacterium associated instead with peptide- and amino acid-derived metabolites, and Flavobacterium and Saccharomycopsis showed correlation patterns opposite to the antioxidant-linked lactic acid bacteria. The authors are careful to stress that these are statistical associations, not proof of causation, and that the functional predictions were inferred from taxonomy rather than measured directly by metagenomics or enzyme assays.

The study has clear limitations—pH, organic acids, and the free-versus-bound phenolic fractions were not fully characterized, and no cultivation or inoculation experiments were performed to test the candidate microorganisms directly. But the practical implications are compelling. For producers of highland barley wine and emerging functional foods, the work suggests that cultivar selection is a powerful lever: black barley delivers a fermented product with inherently stronger radical scavenging capacity, while yellow barley responds more dynamically to fermentation with larger relative gains in phenolics. Future experiments using sterile fermentations, defined co-cultures, and enzyme knockout studies could confirm whether Lactiplantibacillus and Levilactobacillus can be deployed as starter organisms to deliberately boost the phenolic content and antioxidant value of fermented cereal products. In an era when consumers increasingly seek foods with documented functional benefits, this plateau grain—and the microbes that transform it—may offer a scientifically grounded path from traditional brewing to evidence-based functional food design.

Subject of Research: Comparative multi-omics analysis of microbial succession, metabolite profiles, and antioxidant properties during fermentation of black and yellow highland barley.

Article Title: Comparative multi-omics analysis of microbial succession, metabolite profiles, and antioxidant properties in fermented black and yellow highland barley

Article References: Han, M., Hou, H., Wang, H., Zhang, M., Tang, X., Zhou, X., Liu, M., Ma, C., Yang, Q., & Feng, B. (2026). Comparative multi-omics analysis of microbial succession, metabolite profiles, and antioxidant properties in fermented black and yellow highland barley. Food Chemistry: X, 39, Article 104424. https://doi.org/10.1016/j.fochx.2026.104424

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104424

Keywords: highland barley, fermentation, antioxidant activity, flavonoids, anthocyanins, microbial succession, lactic acid bacteria, metabolomics, Pediococcus, Saccharomycopsis, Tibetan barley wine, functional foods

White seabass were once prized catch along the coast from central California to Baja California, but landings plummeted after 1950. Since 1983, California’s Ocean Resources Enhancement and Hatchery Program has spawned wild broodstock and raised juvenile fish to replenish wild populations. Yet larval rearing remains precarious: in past trials, Vibrio species — monitored using selective culture media — were associated with spikes in mortality. Hoping to tame the problem, the research team tested Sanolife® MIC, a commercial probiotic blend of three Bacillus species (B. subtilis, B. licheniformis, and B. pumilus) that has shown promise in shrimp and tilapia systems. The idea was simple: seed the tanks and live feed with beneficial bacteria to suppress pathogenic Vibrio and stabilize the microbial community during the vulnerable early feeding period.

The experiment followed larvae from the egg stage through 60 days post hatch (dph) in sixteen 320-liter fiberglass cone tanks, assigned to four treatment groups: rotifer feeding without probiotic, Artemia-only controls, probiotic-enriched Artemia, and probiotic added directly to rearing water. The team then deployed 16S rRNA amplicon sequencing on the V4 region of the bacterial genome, achieving an impressive average sequencing depth of 164,413 reads per sample. This allowed them to distinguish not just which bacteria were present, but how entire communities reorganized across time, treatment, and sample type — larval fish, culture water, and live feed.

The most important finding was what mattered most: time. When the researchers ran PERMANOVA tests on weighted UniFrac distances — a phylogenetically aware measure of community similarity — days since hatching explained by far the largest share of microbiota variability (R² = 0.202, p = 0.001). The larval microbiome is not a static assemblage but a moving target, remodeled as fish develop from yolk-sac larvae to fully weaned juveniles. Secondarily, the larval microbiota differed significantly from their surrounding culture water (R² = 0.063, p = 0.001), confirming that fish larvae are not simply bathed in — and colonized by — whatever bacteria float past them.

So did the probiotic work? In a word: partially. Sanolife® MIC did successfully incorporate its Bacillus strains into both the culture water and larval fish communities. Bacillaceae ranked among the top three most abundant families in probiotic-treated samples, and probiotic-treated Artemia became dominated by the added bacteria. But the treatment did not meaningfully reshape the broader microbial community, did not reduce Vibrio abundance, and did not improve larval growth or survival (14.2–18.1% survival at 56 dph, with no significant differences among treatments). Substituting rotifers for first-instar Artemia at first feeding also produced no significant shift in either larval or water microbiota. Differential abundance analysis using ANCOM-BC2 confirmed that only Bacillus and Brevibacillus changed between probiotic and control conditions.

What the team did find was a dramatic narrative of microbial succession. In the earliest feeding stages (5–18 dph), Vibrio surged to its peak abundance, coinciding with a sharp drop in bacterial alpha diversity — both evenness and Shannon diversity plummeted just after first feeding, then recovered and plateaued as larvae weaned onto dry feed. The dominant phyla throughout development were Pseudomonadota (Proteobacteria) and Bacteroidota (Bacteroidetes), alongside Bacillota and, from 18 dph onward, Campylobacterota. Nine genera changed significantly over time: marine taxa like Paracoccus, Poseidonibacter, Psychrobium, Colwellia, and Polaribacter increased, while Exiguobacterium, Vibrio, and Ligilactobacillus declined — likely outcompeted by slower-growing K-strategist bacteria as the gut matured.

Perhaps most concerning was the appearance of Tenacibaculum, a genus containing well-known fish pathogens responsible for tenacibaculosis, a disease causing significant economic losses in aquaculture globally. Tenacibaculum was initially overrepresented in culture water but did not colonize the larvae until 46 dph — late in the trial. The researchers note this genus has been found in association with skin lesions on juvenile white seabass. Neither Vibrio nor Tenacibaculum caused observable disease or mortality in this study, but their presence signals a latent threat: opportunistic pathogens ubiquitous in marine environments that could turn pathogenic during stressful events like handling, tagging, or transport.

The fish-water divide also told a fascinating ecological story. Larval fish harbored significantly more taxa associated with vertebrate guts — including Turicibacter, Kineothrix, Akkermansia, Bifidobacterium, Lactobacillus, and Ligilactobacillus — while culture water was dominated by free-living, particle-attached, and nitrogen-cycling marine bacteria like Polaribacter, Planctomycetaceae, and Halieaceae. Many of the fish-enriched taxa are recognized commensals or even candidate probiotics, suggesting the larvae actively cultivate a specialized internal community distinct from their external environment. Over half of the larval ASVs were shared with culture water, but composition differed sharply by unweighted UniFrac analysis.

The authors suggest the probiotic’s failure in this system may reflect dose, timing, or species-specific incompatibility, and future trials will test earlier administration at higher concentrations within the recirculating aquaculture system. Meanwhile, the detailed baseline map of the white seabass larval microbiome offers hatchery managers a diagnostic framework: tracking the 5–18 dph diversity crash and the rise of Tenacibaculum at later stages could flag windows of vulnerability before disease strikes. For a species whose recovery depends on millions of larvae surviving those first fragile weeks, knowing exactly when the microbiome wobbles — and which bacteria are circling — may prove as valuable as any feed formulation or tank design. The dataset is available under NCBI BioProject PRJNA1372260.

The findings carry weight beyond a single hatchery because larval fish microbiomes follow a recognizable developmental arc across marine finfish species. In Atlantic cod, for instance, early colonization is heavily dictated by live feed communities before host-driven selection takes hold, and the white seabass results echo that pattern: external sources matter most at first feeding, while the maturing gut progressively asserts its own selective pressures. This transition from environmentally dominated to host-specialized assemblages is thought to reflect anatomical and immunological maturation of the digestive tract, including the development of gut-associated lymphoid tissue and the gradual establishment of anaerobic niches that favor certain commensal lineages.

The diversity crash observed just after first feeding deserves particular attention from a physiological standpoint. A drop in Shannon diversity during a period of rapid dietary change suggests a temporary ecological bottleneck in which a small number of fast-growing, opportunistic taxa — Vibrio among them — exploit the nutrient pulse introduced by live feeds. Similar boom-and-bust dynamics have been documented in other marine larval systems, where r-strategist bacteria flourish briefly before slower-growing, more specialized competitors establish themselves. The eventual recovery and plateau of diversity indicates that the larval gut ecosystem is resilient, but the transient window of low diversity may represent a period of reduced functional redundancy, when a disturbance could more easily tip the community toward dysbiosis.

Methodologically, the study illustrates why culture-independent sequencing has become essential in aquaculture microbiology. Traditional monitoring with selective media such as TCBS agar captures only a narrow slice of the bacterial community and can misrepresent both the presence and abundance of target genera, since many Vibrio species grow poorly or atypically on such media while some non-target organisms produce false positives. Amplicon sequencing at the depth achieved here — averaging more than 160,000 reads per sample — resolves hundreds of amplicon sequence variants simultaneously, enabling the detection of taxa like Tenacibaculum that would never be flagged by Vibrio-selective screening. This broader lens is what allowed the researchers to identify a late-arriving potential pathogen that routine culture-based surveillance would likely have missed entirely.

The probiotic outcome also contributes to a growing body of evidence that probiotic efficacy in aquaculture is highly context-dependent. Bacillus-based products are attractive commercially because spore-forming strains survive feed processing and storage, and they have delivered measurable benefits in shrimp hatcheries and tilapia nurseries, including improved resistance to streptococcal infections. Yet the white seabass trial shows that successful colonization of the rearing environment does not guarantee community-level effects. The added Bacillus strains integrated into the existing microbial network without displacing residents, suggesting that established communities can absorb newcomers through functional redundancy or competitive exclusion. Factors such as dosing regimen, delivery route, water exchange rates, and the developmental stage at first exposure all plausibly modulate outcomes, which is why the authors advocate earlier and more intensive administration in follow-up trials.

For hatchery operations more broadly, the study underscores the value of longitudinal microbial monitoring as a management tool rather than a purely descriptive exercise. Because the larval microbiota proved far more sensitive to developmental time than to any experimental manipulation, routine sampling at standardized ages could establish expected community trajectories, with deviations serving as early-warning indicators of instability. The identification of gut-associated commensal genera enriched in the larvae — including lactic acid bacteria and Akkermansia-related taxa — also hints at candidate beneficial organisms native to white seabass that could eventually be developed into host-adapted probiotic formulations, an approach increasingly favored over generic commercial products in finfish aquaculture.

Subject of Research: Temporal dynamics of the larval microbiome in hatchery-raised white seabass under probiotic and live feed manipulation

Article Title: Temporal dynamics of the larval microbiota in hatchery-raised white seabass (Atractoscion nobilis) under probiotic and live feed manipulation

Article References: Kunselman, E., Stuart, K., Primus, A., Michelato, M., & Drawbridge, M. (2026). Temporal dynamics of the larval microbiota in hatchery-raised white seabass (Atractoscion nobilis) under probiotic and live feed manipulation. Blue Biotechnology, 3(1), Article 7. https://doi.org/10.1186/s44315-026-00058-w

Image Credits: AI Generated

DOI: 10.1186/s44315-026-00058-w

Keywords: white seabass, larval microbiome, probiotics, Sanolife MIC, Vibrio, Tenacibaculum, aquaculture, 16S rRNA sequencing, live feed, Artemia, hatchery, microbial succession