Allonsius, C. N. | bioRxiv Science

bioRxiv2026

Exopolysaccharides of Lactobacillus crispatus mediate key balancing interactions with the vaginal mucosa

Lactobacillus crispatus is a dominant member of the healthy vaginal microbiota, yet the mechanisms by which it modulates host immunity remain poorly defined, in part due to the lack of tractable in vivo models. Here, we integrate bacterial genetics, in vitro epithelial systems, human-derived data and proteomic approach (Olink) to uncover a critical role for L. crispatus exopolysaccharides (EPS) in shaping the bacteria-vagina interactions. Comparative genomics identified a conserved EPS biosynthetic locus, with the priming glycosyltransferase gene epsE emerging as a regulatory node, in line with its distinct expression in human vaginal samples. Functional disruption of epsE abrogated L. crispatus EPS production and revealed its role for immune modulation. In human vaginal epithelial monolayers, EPS presence enhanced immune-regulatory (LAP TGF-beta-1) and anti-inflammatory (CST5) responses, whereas its absence triggered elevated pro-inflammatory cytokines (IL-1{beta}, IL-6, IL-8) and matrix metalloproteinase (MMP-10). In a 3D vaginal organotypic model, EPS increased chemokines (CXCL5, CXCL6) linked to immune surveillance and the presence of the markers was validated in vaginal samples of healthy volunteers. These findings position EPS as a key immunomodulatory structure of L. crispatus, advancing our mechanistic understanding of host-commensal interactions and informing microbiome-based strategies to promote vaginal health.

microbiology↗

bioRxiv2025

The female intimate microbiome space

Despite its importance in health, the female skin microbiome remains understudied. In this study we explored microbial dispersal across intimate body sites, including the vagina, groins, breast and mouth. Microbial similarity correlated with physical proximity, suggesting dispersal influenced by hygiene or sexual activity. Notably, lactobacilli were unexpectedly abundant on breast skin. These findings highlight the need for research into microbiome dynamics and their implications for womens health.

microbiology↗

bioRxiv2019

Comparative genome analysis of Lactobacillus mudanjiangensis, an understudied member of the Lactobacillus plantarum group

The genus Lactobacillus is known to be extremely diverse and consists of different phylogenetic groups that show a diversity roughly equal to the expected diversity of a typical bacterial genus. One of the most prominent phylogenetic groups within this genus is the Lactobacillus plantarum group which contains the understudied Lactobacillus mudanjiangensis species. Before this study, only one L. mudanjiangensis strain, DSM 28402T, was described but without whole-genome analysis. In this study, three strains classified as L. mudanjiangensis, were isolated from three different carrot juice fermentations and their whole-genome sequence was determined, together with the genome sequence of the type strain. The genomes of all four strains were compared with publicly available L. plantarum group genome sequences. This analysis showed that L. mudanjiangensis harbored the second largest genome size and gene count of the whole L. plantarum group. In addition, all members of this species showed the presence of a gene coding for a putative cellulose-degrading enzyme. Finally, three of the four L. mudanjiangensis strains studied showed the presence of pili on scanning electron microscopy (SEM) images, which were linked to conjugative gene regions, coded on plasmids in at least two of the strains studied. Author summaryLactobacillus mudanjiangensis is an understudied species within the Lactobacillus plantarum group. Since its first description, no other studies have reported its isolation. Here, we present the first four genome sequences of this species, which include the genome sequence of the type strain and three new L. mudanjiangensis strains isolated from fermented carrot juice. The genomes of all four strains were compared with publicly available L. plantarum group genome sequences. We found that this species harbored the second largest genome size and gene count of the whole L. plantarum group. Furthermore, we present the first scanning electron microscopy (SEM) images of L. mudanjiangensis, which showed the formation of pili in three strains that we linked to genes related to conjugation. Finally, we found the presence of a unique putative cellulose-degrading enzyme, opening the door for different industrial applications of these Lactobacillus strains.

microbiology↗