Screening of biofilm formation by beneficial vaginal lactobacilli and influence of culture media components

To assess the ability of vaginal lactobacilli to form biofilm under different culture conditions and to determine the relationship between their growth and the capability of biofilm formation by selected strains.Fifteen Lactobacillus strains from human vagina were tested for biofilm formation by crystal violet staining. Only Lactobacillus rhamnosus Centro de Referencia para Lactobacilos Culture Collection (CRL) 1332, Lact. reuteri CRL 1324 and Lact. delbrueckii CRL 1510 were able to grow and form biofilm in culture media without Tween 80. However, Lact. gasseri CRL 1263 (a non-biofilm-forming strain) did not grow in these media. Scanning electron microscopy showed that Lact. rhamnosus CRL 1332 and Lact. reuteri CRL 1324 formed a highly structured biofilm, but only Lact. reuteri CRL 1324 showed a high amount of extracellular material in medium without Tween.Biofilm formation was significantly influenced by the strain, culture medium, inoculum concentration, microbial growth and chemical nature of the support used for the assay.The results allow the selection of biofilm-forming vaginal Lactobacillus strains and the conditions and factors that affect this phenomenon.