二甲酚（dimethylphenol, DMP，共6种异构体）是自然界中一类常见的芳烃，也是一类重要的化工中间体，但其大量生产使用导致严重的DMP污染问题。微生物在DMP降解中发挥关键作用。微生物如何代谢DMP？怎样更好利用微生物消除DMP污染？这一直是微生物降解领域关注的两个问题。然而，第一个问题的答案尚缺少多块关键拼图，尤其是涉及2,6-DMP降解的遗传和生化知识仍是空白，且其它DMP降解过程中多个关键步骤对应的基因也未被报道。鉴于此，在理想的前期工作基础上，本项目拟鉴定菌株Mycobacterium sp. B5-4代谢2,6-DMP的途径、功能基因及其转录调控机制；同时还将克隆B5-4和其它菌株中负责2,5-DMP和3,5-DMP降解的基因。希望通过本项目实施，基本完成细菌代谢DMP分子机制的拼图，为借助菌株强化、基因强化或合生生物学方法解决DMP污染问题提供菌种和基因资源。

DMPs have six isomers which constitute a common group of aromatic compounds. All six DMPs are chemical intermediates of significance with huge annual output. However, their extensive production and use lead to the lease of DMPs into the environment, threatening aquatic animals and human beings. Microbes play a key role in the elimination of DMPs in the environment. How microbes metabolize DMPs and how to eliminate DMPs contamination using microbes are two questions of interest in the field of microbial degradation. However, the answer of the first question is still far from clear; the genetic and chemical information behind microbial degradation of 2,6-DMP is totally unknown; and several big gaps in the genetic determinants of 2,5-DMP and 3,5-DMP degradation have not been filled. Based on our promising preliminary data, this project plans to identify the catabolic pathway, the genetic determinants and transcriptional regulation of 2,6-DMP catabolism in Mycobacterium sp. strain B5-4; also, we will investigation the genes responsible for the degradation of 2,5-DMP and 3,5-DMP in strain B5-4 and other strains. The expected findings will enhance our understanding of the microbial degradation mechanism of DMPs and benefit the effort to clear DMPs contamination through providing functional strains and genetic elements.