Abstract

A diesel-degrading bacterial strain (F9) was isolated and identified in this study. F9 strain was isolated from diesel polluted seawater. It was a Gram-negative, non-spore-forming bacterium and identified as a strain of Acinetobacter sp. according to its physiological and biochemical properties and 16S rDNA sequence analysis. It had efficient diesel-biodegradability and could grow very well with diesel as its sore carbon resource. At the 7^th day, F9 could remove more than 90% diesel in culture. Gas chromatography-mass spectrometry (GC-MS) results showed that F9 could degrade all alkanes from C11-C21 in diesel. Using degenerate PCR primers, the alkane hydroxylase genes, including AlkB and CYP153A genes, were detected in F9. Products of PCR were sequenced and analyzed. The results showed that F9 had one CYP153A gene and two AlkB genes. The sequence of CYP153A gene in F9 had 99% identity to sequence of CYP153A gene of Acinetobactersp. EB104. The sequence of one AlkB gene had 99% identity to sequence of AlkM gene ofAcinetobacter venetianus strain VE-C3. While, the sequence of the other AlkB gene only had 84% identity to sequence of AlkB gene of bacterium alkW42. The presence of multiple alkane hydroxylase genes in F9 may be the reason why it had efficient diesel-degradability and wide substrate range. In conclusion, F9 strain containing multiple alkane hydroxylase genes belonged to genera Acinetobacter sp and could degrade diesel efficiently. It has potential to be applied in bioremediation of marine diesel pollution.

Key words: Bacterial strain, diesel-degrading, Acinetobacter sp., alkane hydroxylase gene, bioremediation