The testing method of GC-MS.

<div><p>The petroleum hydrocarbons in seawater have been worldwide concern contaminants. Biological method, with the advantages of low cost, minimal environmental impact, and no secondary pollution, is a promising method for petroleum hydrocarbon treatment. In this study, two strains, identified as <i>Stenotrophomonas acidaminiphila</i> and <i>Ochrobactrum</i>, were demonstrated to possess the ability to degrade petroleum hydrocarbons. The mixed culture composed of <i>Stenotrophomonas acidaminiphila</i> and <i>Ochrobactrum</i> at a 2:1 ratio was able to achieve 79.41% degradation of the total petroleum hydrocarbons after 5 days. Besides, the average removal efficiencies of C10-C30 components in petroleum hydrocarbons by <i>Stenotrophomonas acidaminiphila</i>, <i>Ochrobactrum</i>, and mixed culture were 62.98%, 59.14% and 73.30%, respectively. The possible degradation pathways of petroleum hydrocarbons had been speculated through gas chromatography-mass spectrometry (GC-MS) and differential gene expression metabolomics analyses. The toxicity of products from the biodegradation of petroleum hydrocarbons was greatly reduced.</p></div>