微生物降解石油源多环芳香烃的研究进展

石油源多环芳香烃是存在于石油中的一类致畸、致癌污染物,具有以低环(2~3环)为主且取代基比例明显高于其他来源PAHs的组分特征。石油泄露引发的PAHs污染,其降解主要依赖于微生物的活动。本文对能够降解PAHs的微生物种类、降解机理、代谢途径及编码基因进行了概述。从PAHs作为碳源的角度将微生物降解机理划分为能以PAHs为唯一碳源进行生长的降解机理和共代谢机理。对与PAHs有关的好氧和厌氧微生物降解途径及对应的编码基因簇进行了总结。自然界中细菌、放线菌、真菌及藻类都能够降解PAHs,由加氧酶催化的苯环羟基化和还原酶介导的苯环脱芳烃化是好氧和厌氧降解途径的关键步骤,与降解有关的pca,cat,paa,nah,nah-like和bcr基因簇则分别调控好氧和厌氧降解过程。这些进展有助于系统了解石油源PAHs的降解过程、微生物作用机理和分子遗传机制,为进一步利用微生物促进环境生物修复提供理论依据。

Microbial Degradation of Polycyclic Aromatic Hydrocarbons from Crude Oils: A Review

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.