Molecular detection, quantification and distribution of alkane-degrading bacteria in production water from low temperature oilfields

Alkane-degrading bacteria are crucial in the bioremediation of petroleum contamination from soil and groundwater. The alkane monooxygenase (alkB) gene encoding the Alk enzyme involved in aerobic degradation is a potentially functional gene biomarker for the detection of alkane-degrading bacteria. This study describes a denaturing gradient gel electrophoresis (DGGE) assay to facilitate the rapid and sensitive detection of alkB genes in wastewater from oilfield. The results showed that the presence of a considerable genetic diversity of alkB genes in the wastewater as evidenced by a total of 13 unique DNA bands detected. These alkB genes belong to nine genera, including Acinetobacter, Alcanivorax, Acidisphaera, Burkholderia, Geobacillus, Marinobacter, Mycobacterium, Pseudomonas, Rhodococcus and Xanthobacter. The abundance of alkane-degrading bacteria and total bacteria was calculated to range from 1.46 × 103 to 9.89 × 104 cell ml−1 and from 1.18 × 104 to 6.29 × 105 cells ml−1, respectively. The distribution of alkane-degrading bacteria was positively correlated with the environmental temperature and the specific types of n-alkanes in the wastewaters. Our results suggest that alkB-based DGGE methods could describe the diverse alkane-degrading bacteria in oil-degrading community, which may improve the understanding of the treatment for oil-polluted wastewater.