Applied and Environmental Microbiology vol:79 pages:4576-85
Lactobacilli are important for the maintenance of a healthy ecosystem in the human vagina.
Various mechanisms are postulated but so far poorly substantiated by molecular studies such as mutant analysis. Bacterial auto-aggregation is an interesting bacterial phenomenon, which can promote adhesion to host cells and displacement of pathogens. In this study, we report on the identification of a human vaginal isolate, Lactobacillus plantarum strain CMPG5300, which shows a high auto-aggregative and adhesive capacity. To investigate the importance of sortase dependent proteins (SDPs) in these phenotypes, a gene deletion mutant was constructed for srtA, the gene encoding the housekeeping sortase that covalently anchors these SDPs to the cell surface. This mutant lost the capacity to auto-aggregate, showed a decrease in adhesion to vaginal epithelial cells and lost the biofilm forming capacity under the conditions tested. These results indicate that the housekeeping sortase SrtA of CMPG5300 is a key determinant of the peculiar surface properties of this vaginal Lactobacillus strain.