Screening of potential biosurfactant-producing bacteria isolated from seawater biofilm

Seawater represents a specific environment harboring complex bacterial community which is adapted to harsh conditions. Hence, biosurfactant produced by these bacteria under these conditions have interesting proprieties. The screening of biosurfactant producing strains isolated from seawater biofilm was investigated. Specific media, which have been reported to induce biosurfactant production, were used to prepare bacterial cultures and four methods; drop collapse, blue agar, blood-agar lysis and emulsification index, were applied to screen for biosurfactant production. 16 culturable, aerobic bacterial strains were isolated from biofilm in this study. Among these isolates, nine strains were Grampositive and seven were Gram-negative. However the majority of the biosurfactant producer strains were Gram-negative belonging to different genera according to a multitube micromethod for identification of bacteria (API system gallery). Some of the isolated genera such as: Bacillus, Pseudomonas, Micrococcus, Neisseria, and Aeromonas are well known as biosurfactant producers, while other genera, mainly Staphylococcus, Chrysomonas and Photobacterium, were described for the first time as biosurfactant producers in this work.