CHARACTERIZATION OF INDIGENOUS OIL-DEGRADING BACTERIA FROM OIL-POLLUTED SOIL IN CAM RANH, KHANH HOA

Abstract

Bioremediation of oil-contaminated soils using biodegradative activities of microorganisms is a promising approach that is of interest to researchers. The study aimed to isolate oil-degrading bacterial strains from the contaminated soil of Cam Ranh, Khanh Hoa, and develop a robust indigenous bacterial consortium for bioremediation of crude oil pollution. From a total of seven oil-polluted soil samples collected in Cam Ranh, after 3-fold enrichment in liquid mineral salt medium containing 5% crude oil mixed in diesel DO (w/v), 7 bacterial isolates were achieved. Based on the antagonism of 7 strains, 3 microbial consortia were formed and developed well in the condition of liquid mineral salts with 5% crude oil added mixed in DO. In particular, the TH2 consortium revealed the best ability to develop and oil-decomposition of 90% after 13 days of incubation. By analysis of 16S rRNA sequences, four oil-degrading bacteria of TH2 were identified as Bacillus subtilis CR1 (OQ940649), Bacillus siamensis CR4 (OQ940652), Bacillus amyloliquefaciens CR5 (OQ940653), and Pseudomonas citronellolis CR7 (OQ940655), respectively. The optimal conditions for four bacterial isolates were determined at salinity 20‰, pH 7 and temperature 30-37°C. They are suitable for application in the bioremediation of oil-contaminated environments.