Genomic Insights into Lactobacillus gasseri in the Urinary Tract

Four Lactobacillus species tend to dominate the female urogenital microbiota of young healthy women: L. iners, L. crispatus, L. jensenii, and L. gasseri. Studies have associated probiotic influences with L. gasseri. Here we present the results of our comparative genomics study of L. gasseri and its sister taxa L. paragasseri, which is also found in the urogenital microbiota. To date, 68 genomes/assemblies are publicly available for these two species. Fifteen of these genomes are from urinary isolates. Other genomes include fecal, milk, and vaginal isolates. Our analysis identified several genomes classified as L. gasseri that were in fact members of L. paragasseri, confirmed by core genome phylogenomics and average nucleotide identity (ANI) analysis. Niche specialization was not detected. In other words, we did not identify any specific gene acquisitions specific to genomes of isolates from the urinary tract or from the vagina. After reclassifying these genomes, we found that urinary L. paragasseri strains encode for the bacteriocin gasserin while L. gasseri strains do not. Bacteriocins are antimicrobial peptides and may provide L. paragasseri with the probiotic qualities previously associated with L. gasseri.