Phenotypic surface properties (aggregation, adhesion and biofilm formation) and presence of related genes in beneficial vaginal lactobacilli

To evaluate the phenotypic expression of auto-aggregation, adhesion to mucin and biofilm formation of lactobacilli isolated from human vagina and the presence of related genes.Seven different strains of three Lactobacillus species (Lactobacillus gasseri, Lactobacillus rhamnosus and Lactobacillus reuteri) were evaluated. The auto-aggregation property was determined by spectrophotometric assay and flow cytometry. Adhesion and biofilm formation were assayed by crystal violet staining. The presence of the genes encoding sortases, pilin subunits and surface proteins was evaluated by polymerase chain reactions. The two Lact. reuteri strains assayed showed high auto-aggregation, adhesion to mucin and biofilm formation ability. In these strains, the genes encoding three adhesion proteins were identified. In Lact. rhamnosus CRL (Centro de Referencia para Lactobacilos Culture Collection) 1332, pilus-encoding genes were detected. In all Lact. rhamnosus strains assayed, two genes encoding for other surface proteins related to adhesion and biofilm formation were detected.The vaginal lactobacilli assayed exhibited phenotypic and genetic characteristics that were specific for each strain.This is the first study on auto-aggregation, adhesion and biofilm formation of vaginal Lactobacillus strains by phenotypic and genetic assays.