Characterization and genomic analysis of a nitrate reducing bacterium from shale oil in the Ordos Basin and the associated biosurfactant production

Abstract

Bacterial metabolism plays an important role on the formation and exploitation of oil shale, and the cost-efficient and environmentally friendly disposal are of great significance for shale oil sustainable development. In the present study, a promising nitrate reducing bacterium was isolated from shale oil in the Ordos Basin with a superior ability to degrade long-chain alkane and produce biosurfactant, which was identified as Stenotrophomonas maltophilia designated strain WGB211 based on morphological and biochemical characteristics as well as 16 S rRNA sequence analysis. The WGB211 degraded a wide range of medium-long length n-alkanes and exhibited highly efficient in 32 C’s n-alkane degradation of over 73% removal rate within 7 days at 31 °C, pH 6.4 and 230 mg/L 32 C’s n-alkane under response surface methodology (RSM) predicted conditions. The biosurfactant product was identified as a mixture of lipopeptides and glycolipids through Fourier transform infrared spectroscopy (FT-IR). The whole genomic analysis showed that strain WGB211 contained a chromosome of 4913676 bp and 4472 protein-coding genes by Illumina NovaSeq. A great number of genes and enzymes related to alkane degradation, such as flavin-binding protein AlmA1 and AlmA2, and long-chain alkane hydroxylase LadA, were identified based on gene annotation. RT-qPCR analysis showed that a dissimilarity of gene expression could be induced by 32 C's n-alkane. This study suggests that S. maltophilia WGB211 could be a potential species for exploitation of oil shale and its genome analysis is valuable for insight into the molecular basis of bioremediation.