Isolation and characterization of crude-oil-degrading bacteria from oil-water mixture in Dagang oilfield, China

• A new Acinetobacter strain was successfully isolated from oil-water mixture.
• The strain can utilize hexadecane and crude oil as the sole carbon sources.
• AlkB gene was cloned indicating this strain has one alkane metabolic pathway.
• It shows potential use for bioremediation of oil pollution and oil exploitation.

Isolating novel crude-oil-degrading bacteria from oil-water mixture of oil production well and evaluating their degradation capacities are vitally important in the remediation of oil-polluted environments and crude oil exploitation. According to the molecular screening with degenerate primers of alkane hydroxylase gene (alk B), a strain Acinetobacter sp. LS-1 with alk B gene was isolated. This strain exhibited a 99.9% similarity with genus Acinetobacter. This alk B gene which is one of the key enzymes of metabolic process was identified. This gene sequence showed 98% similarity of its nucleotide and related amino acids to the genus Marinobacter but exhibited below 70% similarity to the genus Acinetobacter. This phylogenetic analysis indicated that alk B may have been transferred horizontally between bacteria. The isolated strain could utilize crude oil as the sole carbon, achieving a high degradation (70.3%) in 7 days. Microcalorimetric analysis of the metabolic processes for hexadecane degradation also demonstrated the ability of this strain to utilize hydrocarbons. Thus, this strain enables to degrade hydrocarbons as the sole carbon source from the gene level, combined with material and energy metabolism. These findings will benefit this strain in the remediation of oil-polluted environments and oil exploitation.