Isolation and characterization of biosurfactants produced by Lactobacillus gasseri of vaginal origin

In a healthy host, a balance exists between members of the microbiota, such that potential pathogenic and non-pathogenic organisms can be found in apparent harmony. During infection, this balance can become disturbed, leading to often dramatic changes in the composition of the microbiota. For most bacterial infections, nonspecific antibiotics are used, killing the non- pathogenic members of the microbiota as well as the pathogens and leading to a substantial delay in the restoration of a healthy microbiota. Lactobacillus species dominate the vaginal niche of healthy reproductive age women and are involved in the homeostasis maintenance by preventing the overgrowth of urogenital pathogens. Lactobacilli play key protective roles through different mechanisms such as production of various antimicrobial compounds, co-aggregation, competitive exclusion, immunomodulation and release of biosurfactants (BS). Aim of the study was to investigate the ability of vaginal lactobacilli to produce Biosurfactants (BS), as well as to characterize BS in terms of anti-adhesive and anti-biofilm activities against some representative vaginal pathogens. Production of BS was evaluated by the oil displacement test, which is an indirect, sensitive and simple method for the measurement of molecules’ surface activity. Several lactobacilli strains produced significant amount of biosurfactants: BS produced by L. gasseri BC9 showed the best surface tension at both the highest (10 mg/ml) and the lowest (1.3 mg/ml) concentration. Anti- adhesive and anti-biofilm activities of BS produced by L. gasseri BC9 was evaluated against strains of Staphylococcus aureus and Escherichia coli, respectively. In conclusion, BS isolated from L. gasseri BC9 strain showed antibacterial properties against S. aureus. BS from BC9 strain also displayed anti-adhesive and anti-biofilm abilities mainly against S. aureus. Together, these capabilities may open up possibilities for BS as an alternative therapeutic approach for the prevention and/or treatment of Gram positive hospital-acquired infections.