Department of Microbiology, College of Biological Sciences, University of California, 226 Briggs Hall, 1 Shields Ave., Davis, CA 95616, USA.
Microbiol Mol Biol Rev. 2010 Jun;74(2):250-72. doi: 10.1128/MMBR.00006-10.
Nitroaromatic compounds are relatively rare in nature and have been introduced into the environment mainly by human activities. This important class of industrial chemicals is widely used in the synthesis of many diverse products, including dyes, polymers, pesticides, and explosives. Unfortunately, their extensive use has led to environmental contamination of soil and groundwater. The nitro group, which provides chemical and functional diversity in these molecules, also contributes to the recalcitrance of these compounds to biodegradation. The electron-withdrawing nature of the nitro group, in concert with the stability of the benzene ring, makes nitroaromatic compounds resistant to oxidative degradation. Recalcitrance is further compounded by their acute toxicity, mutagenicity, and easy reduction into carcinogenic aromatic amines. Nitroaromatic compounds are hazardous to human health and are registered on the U.S. Environmental Protection Agency's list of priority pollutants for environmental remediation. Although the majority of these compounds are synthetic in nature, microorganisms in contaminated environments have rapidly adapted to their presence by evolving new biodegradation pathways that take advantage of them as sources of carbon, nitrogen, and energy. This review provides an overview of the synthesis of both man-made and biogenic nitroaromatic compounds, the bacteria that have been identified to grow on and completely mineralize nitroaromatic compounds, and the pathways that are present in these strains. The possible evolutionary origins of the newly evolved pathways are also discussed.
硝基芳香族化合物在自然界中相对较少，主要通过人类活动引入环境。这一重要的工业化学品类别广泛用于许多不同产品的合成，包括染料、聚合物、农药和炸药。不幸的是，它们的广泛使用导致了土壤和地下水的环境污染。硝基基团在这些分子中提供了化学和功能多样性，也导致了这些化合物难以生物降解。硝基基团的吸电子性质，加上苯环的稳定性，使硝基芳香族化合物具有抗氧化降解的能力。其急性毒性、致突变性和易于还原为致癌芳香胺进一步增加了它们的难降解性。硝基芳香族化合物对人类健康有害，并被美国环境保护署列为环境修复的优先污染物。尽管这些化合物大多数是人工合成的，但受污染环境中的微生物已经通过进化出新的生物降解途径来适应它们的存在，这些途径将它们作为碳、氮和能源的来源加以利用。本综述概述了人为和生物源硝基芳香族化合物的合成、已鉴定出能生长并完全矿化硝基芳香族化合物的细菌以及这些菌株中存在的途径。还讨论了新进化途径的可能的进化起源。
