The vaginal microbiota associates with the regression of untreated cervical intraepithelial neoplasia 2 lesions

Emerging evidence suggests associations between the vaginal microbiota (VMB) composition, human papillomavirus (HPV) infection, and cervical intraepithelial neoplasia (CIN); however, causal inference remains uncertain. Here, we use bacterial DNA sequencing from serially collected vaginal samples from a cohort of 87 adolescent and young women aged 16–26 years with histologically confirmed, untreated CIN2 lesions to determine whether VMB composition affects rates of regression over 24 months. We show that women with a Lactobacillus-dominant microbiome at baseline are more likely to have regressive disease at 12 months. Lactobacillus spp. depletion and presence of specific anaerobic taxa including Megasphaera, Prevotella timonensis and Gardnerella vaginalis are associated with CIN2 persistence and slower regression. These findings suggest that VMB composition may be a future useful biomarker in predicting disease outcome and tailoring surveillance, whilst it may offer rational targets for the development of new prevention and treatment strategies

Bacteriocin production and gene sequencing analysis from vaginal Lactobacillus strains

The human vagina is a complex and dynamic ecosystem containing an abundance of microorganisms. In women of childbearing age, this system is dominated by Lactobacillus spp. In the present work, seventeen newly isolated vaginal strains were identified by 16S rDNA sequencing and were investigated for their antimicrobial properties. Twelve of the isolated Lactobacillus strains showed activity against one or more microorganisms. Sixand five of them produced substances that inhibited the growth of two different Klebsiella strains and Staphylococcus aureus, respectively. Two lactobacilli strains were active against an Escherichia coli strain, one isolate was active against an Enterococus faecalis strain and another lactobacilli strain showed antimicrobial activity against a Candida parapsilosis strain. The nature of the active compounds was additionally studied, and the presence of bacteriocin-like substances was proved. The genes related to the bacteriocin production in three of the newly isolated strains were identified and sequenced. The presence of gassericin A operon in the genome of the species Lactobacillus crispatus was described for the first time. The presence of antimicrobial activity contributes to their possible use as potential probiotic strains after further research

GENOMIC APPROACHES TO YEAST TAXONOMY

ABSTRAC

Surface-associated MUC5B mucins promote protease activity in Lactobacillus fermentum biofilms

Background: Mucosal surfaces are coated with layers of mucus gel that protect the underlying tissues and promote colonization by members of the commensal microflora. Lactobacillus fermentum is a common inhabitant of the oral cavity, gastrointestinal and reproductive tracts and is one of the most important lactic acid bacteria contributing to the formation of a healthy intestinal microflora. We have investigated the proteolytic activity in L. fermentum in response to interactions with the MUC5B mucin, which is a major component of mucus gels at sites colonized by this micro-organism. Methods: Biofilms of Lactobacillus fermentum were established in mini-flow cells in the presence or absence of human salivary MUC5B. The proteolytic activity of biofilm cells was examined in a confocal scanning laser microscope with a fluorescent protease substrate. Degradation of MUC5B by L. fermentum was analysed using SDS-PAGE followed by Western blotting with antisera raised against the MUC5B peptide. Cell surface proteins differentialy expressed in a MUC5B-rich environment were identified with the aid of comparative two-dimensional electrophoresis followed by LC-MS/MS. Results: Lactobacillus fermentum adhered well to surfaces coated with MUC5B mucin and in biofilms of L. fermentum formed in a MUC5B environment, the proportion of proteolytically-active cells (47 ± 0.6% of the population), as shown by cleavage of a fluorescent casein substrate, was significantly greater (p < 0.01) than that in biofilms formed in nutrient broth (0.4 ± 0.04% of the population). Thus, the presence of MUC5B mucins enhanced bacterial protease activity. This effect was mainly attributable to contact with surface-associated mucins rather than those present in the fluid phase. Biofilms of L. fermentum were capable of degrading MUC5B mucins suggesting that this complex glycoprotein can be exploited as a nutrient source by the bacteria. Comparison of the surface proteomes of biofilm cells of L. fermentum in a MUC5B environment with those in nutrient broth using two-dimensional electrophoresis and mass spectroscopy, showed that the enhanced proteolytic activity was associated with increased expression of a glycoprotease; O-sialoglycoprotein endopeptidase, as well as chaperone proteins such as DnaK and trigger factor. Conclusions: Adhesion to mucin-coated surfaces leads to a shift towards a more protease-active phenotype within L. fermentum biofilms and proteases produced within the biofilms can degrade MUC5B mucins. The enhanced proteolytic activity was associated with an increase in O-sialoglycoprotein endopeptidase on the cell surface. We propose that the upregulation of chaperone proteins in the mucin environment may contribute to the protease-active phenotype through activation of the glycopeptidase. This would represent one way for commensal lactobacilli e.g. L. fermentum to exploit complex substrates in their local environment in order to survive on mucosal surfaces