Genomics and biodegradation properties of an oleophilic bacterium isolated from shale oil sludge

Abstract

Shale oil exploitation is accompanied with the generation of a large quantity of oily sludge. In order to provide suitable microbial resources for treating the growing amount of oily sludge, a microbial strain was isolated and purified from the sewage sludge produced in Daqing shale oil field in this study. The isolated strain in the sludge, temporarily termed FM-1, was identified by morphological, biochemical experiments and 16S rDNA sequencing. At the same time, the protein coding genes of the strain FM-1 were classified by genome-wide sequencing and analyzed its genetic characteristics. The degradation effect of FM-1 was detected to C₁₂, C₁₇ and crude oil and sludge samples by gas chromatography and spectrophotometer. The results confirmed that FM-1 was Bacillus proteolyticus. The whole genome sequencing data analysis showed that there were 1495 protein coding genes related to metabolism, including 384 genes for carbohydrate metabolism. All the genes related to the degradation function, such as almA, mdhA, CYPs, ladA, catD, catE and fadE, were enriched in the oxidative phosphorylation signaling pathway, indicating that FM-1 had abundant genes associated with petroleum hydrocarbon degradation. The strain FM-1 could utilize C₁₀-C₄₀ petroleum hydrocarbons as the sole carbon source, and the degradation rate of crude oil was 17.5% in seven days under the experimental conditions. The degradation rate for petroleum hydrocarbon pollutants in shale oil sludge was as high as 91.5% in 28 days. Literature and patent searches found that Bacillus proteolyticus was a kind of new efficient petroleum hydrocarbon degrading bacterium, which had been obtained the Chinese invention patent.