微生物降解典型高分子量多环芳烃的研究进展

Progress in Microbial Degradation of Typical HMW-PAHs

高分子量多环芳烃(high molecular weight polycyclic aromatic hydrocarbons,HMW-PAHs)属于持久性污染物,与低分子量多环芳烃(low molecular weight polycyclic aromatic hydrocarbons,LMW-PAHs)相比更难被降解.微生物修复是解决HMW-PAHs污染问题的有效手段.该文以2种典型HMW-PAHs——芘和苯并[a]芘为例,对影响其微生物降解效率的因素、提高降解率的强化手段和主要降解途径进行阐释,深入剖析微生物的降解调控机制,并对未来的研究和发展提出了展望,以期为微生物降解HMW-PAHs的相关研究提供参考.结果表明:①大多数微生物在中温、中性条件下对HMW-PAHs具有较好的降解性能,不同多环芳烃在降解过程中存在相互作用;②就HMW-PAHs的微生物强化降解手段而言,表面活性剂吐温80对降解的促进作用较为明显,生物炭是较为优良的固定化材料,在受体菌株中表达降解基因以构建基因工程菌是促进HMW-PAHs微生物降解的有效方式;③芘和苯并[a]芘主要通过K区氧化和LMW-PAHs途径降解;④由双加氧酶催化的羟基化是HMW-PAHs降解过程中的重要步骤;⑤多环芳烃的初始氧化过程也涉及细胞色素P450单加氧酶的活性.目前,基因工程菌的长效稳定性是限制相关技术广泛应用的瓶颈问题,未来需要综合多组学数据从基因、转录、蛋白和代谢水平对HMW-PAHs的微生物降解机制进行全面、深入地解析,为构建高效稳定的重组菌株提供理论支撑.

High molecular weight polycyclic aromatic hydrocarbons(HMW-PAHs)are persistent pollutants that are more difficult to degrade than low molecular weight polycyclic aromatic hydrocarbons.Microbial remediation is an effective means to solve the issue of HMW-PAHs pollution.This article takes two typical HMW-PAHs(namely pyrene and benzo[a]pyrene)as examples to outline the main degradation pathways,the factors affecting the microbial degradation efficiency,and enhancement methods to improve the rate of degradation.We also provide an in-depth analysis of the microbial degradation mechanism and propose prospective areas for future research and development.The results show that:(1)Most microorganisms have good degradation performance on HMW-PAHs under moderate temperature and neutral conditions,and different polycyclic aromatic hydrocarbons interact during the degradation process.(2)As far as the microbial enhanced degradation of HMW-PAHs is concerned,Surfactant Tween 80 has a more obvious promotional effect on degradation,biochar is an excellent immobilization material,and expressing degradation genes in recipient strains to construct genetically engineered bacteria is an effective way to promote the degradation of HMW-PAHs by microorganisms.(3)Pyrene and Benzo[a]pyrene are mainly degraded through K-zone oxidation and LMW-PAHs pathway.(4)The hydroxylation catalyzed by dioxygenase is an important step in the degradation process of HMW-PAHs and the initial oxidation process of polycyclic aromatic hydrocarbons also involves Cytochrome P450 monooxygenase activity.At present,the long-term stability of genetically engineered bacteria is a bottleneck issue that limits the wide application of related technologies,in the future,a comprehensive analysis of the microbial degradation mechanism of HMW-PAHs at genetic,transcriptional,protein,and metabolic levels is required in order to provide theoretical support for the construction of highly efficient and stable recombinant strains.