Hydrocarbon degradation by a newly isolated thermophilic Anoxybacillus sp. with bioemulsifier production and new alkB genes

Abstract

Interest in biodegradation of petroleum derived pollutants by thermophilic bacteria has been steadily increasing in recent decades. In this work, a newly isolated thermophilic bacterial strain was isolated from a deep petroleum reservoir and identified as Anoxybacillus sp. WJ-4 based on an analysis of its physiological characteristics, 16S rRNA sequencing, GC content and cellular fatty acids. It is the first report that strain WJ-4 can degrade a wide range of hydrocarbons (C8–C22) at 67 °C. The production of an oligosaccharide–lipid–peptide bioemulsifier was detected. It exhibited an excellent emulsification activity with various oil phases (EI₂₄ > 60%), and the ability to increase cell surface lipophilicity during degradation, but has no significant impact on surface tension, with a reduction from 72.22 mN m⁻¹ to 52.45 mN m⁻¹. Four alkane monooxygenase genes showed a high phylogenetic relationship (>95%) with alkB genes from Geobacillus. These results indicate that this newly isolated bacterial strain and its bioemulsifier have great potential for environmental remediation and petroleum recovery under thermophilic conditions.