Antimicrobial and anti-adhesive properties of biosurfactant produced by lactobacilli isolates, biofilm formation and aggregation ability

This study aimed to investigate the antimicrobial and anti-adhesive properties of biosurfactant extracted from ten lactobacilli species isolated from Egyptian dairy products. The produced biosurfactants showed distinct antimicrobial and anti-adhesive activities against several pathogenic microorganisms. Furthermore, lactobacilli isolates were studied for biofilm formation and lactic acid production in different growth media. All lactobacilli isolates produced biofilm on polystyrene surface in all media tested to different degrees. L. acidophilus showed the highest biofilm formation in Rogosa medium. However, the highest lactic acid production was recorded by L. brevis (39.63 g/L), followed by L. reuteri (33.32 g/L) in MRS medium. Evaluation based on in vitro studies including auto-aggregation and co-aggregation with three pathogenic bacterial strains was further analyzed. All lactobacilli isolates tested were able to auto-aggregate (ranging from 51.12% to 78.17% assessed at 5 h of incubation). The lactobacilli isolates co-aggregate with the tested bacterial strains to different degrees; among them L. delbrueckii showed the highest scores of co-aggregation with Candida albicans ATC70014, reaching 59.37%. The aggregation ability exhibited by the isolated lactobacilli, together with the antimicrobial and anti-adhesive properties observed for their biosurfactants, opens future prospects for their use against microorganisms responsible for diseases and infections and as effective probiotic strains.