Isolation and molecular identification of surface-active agent producing bacteria from marine environments

Seawater samples collected from different locations on the Mersin coastline were subjected to pre- enrichment and isolation to obtain surfactant-producing bacteria. In total, 52 bacteria were isolated. Pure cultures were grown in the biosurfactant production medium, and cell-free culture broths were obtained for use in screening tests. The presence of biosurfactant was evaluated by applying the drop collapse test, parafilm M test, CTAB-methylene blue agar test, and oil displacement tests with culture fluids. In addition, the capacity of cell-free culture fluids to emulsify cyclohexane, benzene, toluene, and xylene was determined by calculating the emulsification index. As a result of molecular diagnostics based on 16S rDNA sequence analysis, it was determined that isolates of biosurfactant-producing bacteria that show effective surface and interface activity are members of the Pseudomonas, Enterobacter, Staphylococcus, and Klebsiella genera. The anionic biosurfactant produced by Pseudomonas sp. strain HYN-8 was determined to be the most effective biosurfactant with an oil displacement diameter of 40 mm.