Maternal host immune system responses to cervicovaginal microbiota influence the risk of microbial-driven spontaneous preterm birth (sPTB). Immunoglobulins are present in cervicovaginal fluid (CVF). There are decreased IgG concentrations in women with CST I compared to CST IV, but their role in sPTB is unclear. Here, we investigate immunoglobulin coating of vaginal bacteria in 100 women at high-risk of sPTB (48 sPTB vs 53 term). Lactobacillus-dominated communities, especially L. crispatus-dominated, had higher proportions of IgG coating than high diversity, Lactobacillus-depleted communities. There was a positive correlation between IgG and IgG2 coating, indicating IgG2 was the main bound subclass. The percentage of bacterial coating by IgG and IgG2 was higher in women who delivered at term compared to preterm, and IgG coating negatively correlated with concentrations of CVF pro-inflammatory immune mediators. IgG and IgG2 both bound to L. crispatus surface layer proteins (SLPs), identifying SLPs as potential targets of antibody binding associated with immune homeostasis and term birth. Our results reveal an association between vaginal bacterial antibody coating and mucosal microbe-immune homeostasis with reduced cervicovaginal inflammation and term birth. These represent a potential component of host-microbe interactions associated with pregnancy outcome.
The vaginal microbiome influences reproductive outcomes, yet strain-level dynamics during assisted reproductive treatment remain unexplored. Existing studies rely on species-level resolution that cannot distinguish within-species functional heterogeneity, leaving mechanistic questions unanswered. We conducted longitudinal shotgun metagenomic sequencing of vaginal samples from 41 women undergoing IVF/ICSI treatment across six timepoints (pre-stimulation baseline through pregnancy testing; 186 samples total). Strain-level analysis using inStrain revealed that Lactobacillus crispatus genomic stability and Lactobacillus iners adaptive flexibility both associate with pregnancy success, representing a reciprocal dynamic pattern. Functional protein analysis identified two outcome-associated targets: Inerolysin, a cholesterol-dependent cytolysin from L. iners, and L-lactate dehydrogenase (L-LDH) from L. crispatus. Structural modeling suggested that the Success-specific Inerolysin S429P mutation is predicted to disrupt cholesterol-binding, potentially attenuating cytolytic activity, while the L-LDH P169L mutation may enhance catalytic efficiency. Four orthogonal computational methods (FoldX thermodynamic calculation, ESM-1v evolutionary scoring, ConSurf conservation analysis, and 10 ns molecular dynamics simulation) provided convergent computational evidence supporting these structural interpretations. Critically, these protective variants were enriched at baseline (T1) rather than arising during treatment, indicating that pre-existing strain genetics predispose to differential responses under hormonal stress. A baseline 18-SNV prediction panel achieved an internal cross-validation AUC of 0.945 and an external validation AUC of 0.784 in an independent cohort (n = 69) sequenced on a multiplex amplicon PCR platform. These findings reveal strain-level functional variants as candidate mechanistic determinants of reproductive success and potential biomarkers for personalized risk assessment in ART. The reciprocal dynamics of L. crispatus stability and L. iners adaptive flexibility, together with the dual-protein mutation pattern, suggest targets for strain-specific probiotic interventions. All computational predictions require experimental validation through biochemical and functional assays.
Understanding the spatial distribution patterns and driving mechanisms of plant-associated microbial communities across multiple scales is essential for uncovering the generation and maintenance of microbial diversity under plant influence. However, large-scale evidence on the biogeographical patterns of seagrass-associated microbes remains scarce. Here, we sequenced microbial communities in four microhabitats (seawater, phyllosphere, rhizosphere, and sediment) of Zostera japonica beds in China, generating 480 amplicon sequencing datasets and 40 metagenomes. Subsequent analysis explored the structure and functional potential of microbial communities in these microhabitats. The microbial community exhibits significant spatial distribution patterns, characterized by latitudinal distribution patterns and distance decay relationships. While the null model results suggest a dominance of random processes in the construction of microbial communities in Zostera japonica beds, NST analysis reveals a transition from stochasticity to determinism in the assembly of rhizosphere bacterial communities with increasing latitude. Response ratio and GAM analysis further demonstrate differential responses of bacterial and fungal communities to environmental factors, indicating selective regulation of microbial groups by specific environmental drivers in different microhabitats. Functional analysis reveals that key genes involved in nitrogen and sulfur metabolism (such as nirS, norBC, cysNDCH, and cysJI) display latitudinal gradient changes and microhabitat-specific differences in annotated microbes. For example, the cysC gene found in northern sampling points is sourced from Actinomycetota, Bacteridota, and Cyanobacteriota, while in southern sampling points, it primarily comes from Campylobacterota and Pseudomonadota, highlighting the functional adaptability of microbes to environmental heterogeneity. As the first systematic investigation into the biogeographic patterns of microbial communities associated with marine macrophytes, this study not only elucidates the multi-scale distribution patterns of Zostera japonica bed microbiomes but also establishes a theoretical framework for the dual regulation of microbial communities by latitude and microhabitat. The discoveries provide new insights into further investigating the interactions between microbes and seagrasses, as well as the potential for biogeochemical cycling. They contribute to understanding the adaptive strategies of seagrass ecosystems under different environmental pressures and how microbial communities respond to these stressors. This information is crucial for assessing the health of seagrass beds, predicting their response to environmental changes, and formulating effective conservation and management measures based on scientific evidence.
Mucoromycotina fungi are known to enhance plant performance under nutrient-deficient conditions by restructuring rhizosphere microbial communities and mobilizing soil nutrients. However, their functional roles in nutrient-rich soils remain poorly understood. Here, we investigated whether the plant-beneficial fungus Gongronella butleri w5 (w5) can promote the growth of Solanum lycopersicum under phosphorus-rich conditions and explored the underlying tripartite interactions among plants, fungi, and bacteria. Greenhouse experiments, soil microcosm analyses, high-throughput sequencing, functional assays, and host-induced gene silencing revealed that w5 significantly enhanced plant biomass, root development, and photosynthetic efficiency despite not altering soil nutrient availability. w5 inoculation reshaped the rhizosphere microbiome, enriching indole-3-acetic acid (IAA)-producing bacterial taxa. Bacillus megaterium and Bacillus zanthoxyli, identified as key IAA producers, were isolated from the w5 hyphosphere. Tripartite interaction assays showed that w5 imports plant-derived sucrose through the transporter GspSUT1, hydrolyzes it into glucose and fructose, and releases these hexoses into the rhizosphere, thereby facilitating bacterial colonization and enhancing IAA biosynthesis. Silencing GspSUT1 significantly impaired hexose secretion and subsequent bacterial IAA production, thereby disrupting the synergistic plant growth promotion effect. Our findings reveal a carbon-driven mechanism by which Mucoromycotina fungi establish a metabolic niche to drive synergistic plant development in nutrient-rich soils. By acting as an ecological “invertase” to reallocate plant sucrose into hexoses, w5 enriches IAA-producing bacteria. This carbon-hormone coupling synergistically improves root architecture, photosynthetic capacity, and nutrient uptake. These insights highlight the functional plasticity of Mucoromycotina fungi in shaping rhizosphere microbiomes and their potential as sustainable biological inputs.
Apple ring rot, caused by the fungal pathogen Botryosphaeria dothidea, is a devastating disease that causes substantial production and postharvest losses worldwide. Microbial volatile organic compounds (VOCs) are promising biocontrol agents against postharvest fungal diseases. However, how VOCs produced by Streptomyces albidoflavus suppress B. dothidea and whether they are associated with changes in the apple microbiota and the host transcriptional response remains largely unexplored. This study integrated volatilome profiling, microbiome analysis, VOC-bacterial interaction assays, and apple transcriptome profiling to investigate how G1-VOCs suppress apple ring rot. G1 showed strong VOC-mediated inhibitory activity against B. dothidea in bipartite plate and detached fruit assays. GC–MS analysis identified differentially abundant volatiles associated with sesquiterpenoid, triterpenoid, and phenylalanine metabolism, and selected VOC standards impaired fungal growth, membrane integrity, and biofilm formation under the tested assay conditions. 16S rRNA gene amplicon analysis revealed that G1-VOC exposure under pathogen challenge was associated with a simplified, Pseudomonas-dominated bacterial community in internal lesion-margin tissues, accompanied by increased Pseudomonas-specific 16S rRNA gene copies. The cultivable isolate Pseudomonas paracarnis aNRL1, recovered from G1-VOC-treated lesion-margin tissues, matched the enriched Pseudomonas-assigned ASV_2, strongly inhibited B. dothidea in vitro, and reduced lesion development on apple fruit. Selected G1-associated volatiles exerted compound-specific effects on aNRL1 growth, biofilm formation and motility. Apple transcriptome analysis further revealed pathogen-dependent remodeling of brassinosteroid signaling, together with increased expression of genes related to mitogen-activated protein kinase (MAPK), lipid metabolism, and cuticle/wax biosynthesis. Together, these findings support a multilayered model in which G1-derived VOCs directly impair B. dothidea physiology while coinciding with Pseudomonas-dominated restructuring of the internal lesion-margin bacterial community and host barrier- and defense-associated transcriptional remodeling, with P. paracarnis aNRL1 providing a cultivable functional link to the enriched Pseudomonas signal.
