Study on biological degradation and transform characteristics of different components in petroleum hydrocarbon used by bacterial consortium

Some oil-degradation bacterial strains, designated as F1, F2, A5, A6, and D4, were screened and isolated from oil-contaminated soil at the Huaqing Oilfield of Gansu Province, China. The degradation of n-alkanes, hopanes and aromatic hydrocarbons was detected by GC–MS, and biological transform characteristics of n-alkanes, hopanes, aromatic hydrocarbon had been analyzed by various biological marker ratios. The results show that the highest degradation rate of A5, D4 and the mixed bacteria H for high carbon normal alkanes (C₂₈–C₃₉) is more than 70 %. The degradation rate of mixed bacteria H for n-alkanes is relatively balanced. The max w(∑C₂₁₋/∑C₂₂₊) ratio is 0.75, indicating that F2 predominately degrades higher molecular weight n-alkanes. The various strains can promote the transition from less stable R configuration of pentacyclic triterpenes to stable S configuration in 7 days. The w(Ts)/w(Tm) of A5 for hopanes is biggest (0.96), indicating that transformation is most complete. For hopanes, the mixed bacteria H have the best degradation rate and the advantages are obvious. Single bacteria and the mixed bacteria H all have a strong demethylation effect on the naphthalene ring, wherein F1, A5 and D4 have the strongest effects. The mixed bacteria H have an obvious degradation effect on chrysenes. As the research object, this paper systematically studied the degradation and biomarkers of n-alkanes, hopanes and aromatic hydrocarbons by means of ultraviolet spectroscopy and GC–MS to provide basic information for further study of petroleum-contaminated soil remediation technologies.