Characterization of key alkane degradation genes from a petroleum hydrocarbon degradation Acinetobacter sp. Tust-DM21

Abstract:

[Background] Acinetobacter sp. Tust-DM21 (GenBank: KX390866) is a highly efficient petroleum degrading bacteria isolated early from the water-oil mixed sample collected from the waste oil area of the Bohai Bay offshore oil exploration vessel in this laboratory. It exhibits strong degradability to short, medium and long chain alkanes. [Objective] To investigate the optimal conditions of the strain for degradation at the application level and to investigate the role of degradation genes at the bioinformatics level. [Methods] The strain was incubated at different temperatures and pH for 144 h. Changes in petroleum hydrocarbon components were determined by GC-MS internal standard methods, and the best degradation condition was calculated. Meanwhile, the degrading genes were identified in its genome by bioinformatics analysis, and seven homologous genes were selected for each gene and their protein sequences were compared. Real-time PCR analysis of these two genes at 0?144 h were performed for their transcription expression research. [Results] The optimal degradation conditions were 35 °C and pH 8.5. The relative degradation level of petroleum hydrocarbon under this optimal condition can reach up to 97.5%. The degradation rate was 98.5% for long-chain alkanes, 81% for cycloalkanes and 87% for aromatics. Meanwhile, the common alkane degradation gene alkB (Genbank: MH368539) and the long-chain alkane degradation gene almA (Genbank: MH357335) were found in its genome, the proteins of the two degradation genes are similar to their homologous proteins, and the similarity of the same genus is the highest. Real-time PCR showed that gene relative expression increased gradually over time. [Conclusion] It exhibits strong degradability to short, medium and long chain alkanes under the optimal degradation conditions, especially for long-chain alkanes. Combining with the growth trend in this time period, it was demonstrated that the strain growth and degradation were associated with up-regulated expression of the alkB and almA genes.