Biosurfactant Production and Biological Removal of Bulk Oil using Native Strains Isolated from the Southern Shore Lines of Caspian Sea

Nowadays, biodegradation of oil pollution using native bacteria isolates is considered in different research programs. The purpose of this study was to investigate biosurfactant production and degradation of oil spills on Caspian Sea coastlines using native bacterial isolates. Sediment and oil spills samples were isolated from seven stations in the coasts of Bandar Anzali and Kiah Shahr. Biosurfactant production was evaluated using quantitative and qualitative methods such as hemolysis on blood agar, oil spreading method, droplet disintegration, emulsification activity and surface tensile test. Also, total hydrocarbon of oil was estimated. Biodegradation of compounds in sediments and petroleum analyzed using gas chromatography mass spectrometry (GC-MS) method. Identification of strains was performed using different morphological, biochemical and sequencing of 16S rRNA genes. Amongst 115 isolates, 57 isolates showed biosurfactant activity based on qualitative methods, and 15 strains with highest biological removal efficiency were selected for further studies. The spectrophotometry results showed the J3 isolate could remove 94.6% of oil within 7 days, was the most potent isolate in removal of hydrocarbons. Gas chromatography analysis indicated that 90% of aliphatic compounds were removed byJ3 strain in 21 days. The isolates J3, J5, and J12, which showed highest biosurfactant activity, were identified as strains of Bacillus cereussenso latu, Staphylococcus aureus and Pseudomonas aeruginosa, respectively. Discussion and conclusion: The results of this study showed that the isolated strains showed suitable decreasing hydrophobicity and removal of oil hydrocarbons. So, it can be concluded that isolated J3, J5 and J12 are potent microorganisms in cleaning of contaminated waters by oil and other hydrocarbons.