A Lactobacillus-derived biosurfactant inhibits biofilm formation of human pathogenic Candida albicans biofilm producers

Fifteen lactic-acid bacteria, isolated from fresh fruits and vegetables produced biosurfactants in the mid-exponential phase (5 hours). Twelve isolates were genotipically identified to belong to the genus Lactobacillus. Among these, the Lactobacillus sp. CV8LAC, isolated from cabbage, showed the largest oil spreading halo. Extracted CV8LAC biosurfactant reduced the water surface tension from 70.92 mN/m to 47.68 mN/m and its CMC was 106 μg/mL. The CV8LAC biosurfactant significantly (p<0.05) inhibited the adhesion of two Candida albicans pathogenic biofilmproducer strains (CA-2894 and DSMZ 11225) in pre-coating and co-incubation experiments. In pre-coating assays, biofilm formation of the strain CA-2894 was reduced by 82% at concentration of 312.5 μg/ml and that of DSMZ 11225 by 81% at 625 μg/ml. In co-incubation assays, biofilm formation of CA-2894 and DSMZ 11225 was inhibited by 70% at 160.5 μg/well and by 81% at 19.95 μg/well, respectively. No inhibition of both C. albicans planktonic cells was observed, thus indicating that the biosurfactant displayed anti-biofilm formation but not antimicrobial activity.