Biodegradation of hydrocarbons by Purpureocillium lilacinum and Penicillium chrysogenum from heavy oil sludge and their potential for bioremediation of contaminated soils

Heavy oil sludge as a highly hazardous solid waste poses potential pollution risks to the ecological environment. Microbial degradation of petroleum hydrocarbons is an emerging strategy for controlling the environmental pollution by oil sludge. Two hydrocarbon-degrading fungi, designated HF and HQ, were isolated from heavy oil sludge collected at Tahe Oilfield, Xinjiang, Northwest China. Based on morphological analysis and gene sequencing, HF and HQ were identified as Purpureocillium lilacinum and Penicillium chrysogenum, respectively. When supplemented with a small amount of additional carbon (soluble starch) and nitrogen (yeast extract) sources, HF and HQ were able to biodegrade hydrocarbons in oil sludge. Following fungal treatment (30 days), the relative abundances of various hydrocarbon components changed in distinct patterns based on gas chromatography-mass spectrometry. The mean degradation rate of HF for cycloalkanes, n-alkanes, aromatics, and iso-alkanes was 100.0%, 21.2%, 15.1%, and 14.5%, respectively. HQ showed contrasting effects on hy-drocarbon composition, as indicated by the decrease of n-alkanes (1.3%) and the increase of cycloalkanes, ar-omatics, and iso-alkanes (82.6%, 10.2%, and 11.9%, respectively). Approximately 15.3% and 7.6% of total petroleum hydrocarbons in modified oil sludge were removed by HF and HQ, respectively. The results provide empirical evidence for application of P. lilacinum HF and P. chrysogenum HQ as candidate hydrocarbon degraders in bioremediation of oil sludge-contaminated soils.