Abstract:Polycyclic aromatic hydrocarbons (PAHs) from crude oils is a kind of teratogenic and carcinogenic contaminant, in which the low aromatic nucleus ring (2-3 ring) are the dominated components and the substituent group ratio is significantly higher than those from other origins. The degradation of PAHs caused by oils leakage are mainly dependent on microbial activities. This paper summarizes the microbial species, degradation mechanisms, metabolic pathways and coding genes with relation to PAHs biodegradation. The degradation mechanisms are divided into co-metabolism mechanism and the mechanism in which PAHs could be acted as the only carbon source of microbial population from the perspective of carbon source. The degradation pathways of aerobic and anaerobic microorganisms associated with PAHs and corresponding encoding gene clusters are also elaborated in this paper. In natural environment, bacteria, actinomycetes, fungi and algae can degrade PAHs. The hydroxylation and dearomatization of benzene respectively catalyzed by oxygenases and reductases are the key steps in aerobic and anaerobic degradation pathways. Moreover, pca, cat, paa, nah, nah-like and bcr gene clusters associated with degradation regulate the aerobic and anaerobic degradation process respectively. These advances can contribute to systematically understand the PAHs degradation process, the mechanism of microbial action and molecular genetic mechanisms, and thus can provide a theoretical basis for further utilization of microorganisms in environmental bioremediation.