Chaudhry G R, Chapalamadugu S
Department of Biological Sciences, Oakland University, Rochester, Michigan 48309.
Microbiol Rev. 1991 Mar;55(1):59-79. doi: 10.1128/mr.55.1.59-79.1991.
In this review we discuss the degradation of chlorinated hydrocarbons by microorganisms, emphasizing the physiological, biochemical, and genetic basis of the biodegradation of aliphatic, aromatic, and polycyclic compounds. Many environmentally important xenobiotics are halogenated, especially chlorinated. These compounds are manufactured and used as pesticides, plasticizers, paint and printing-ink components, adhesives, flame retardants, hydraulic and heat transfer fluids, refrigerants, solvents, additives for cutting oils, and textile auxiliaries. The hazardous chemicals enter the environment through production, commercial application, and waste. As a result of bioaccumulation in the food chain and groundwater contamination, they pose public health problems because many of them are toxic, mutagenic, or carcinogenic. Although synthetic chemicals are usually recalcitrant to biodegradation, microorganisms have evolved an extensive range of enzymes, pathways, and control mechanisms that are responsible for catabolism of a wide variety of such compounds. Thus, such biological degradation can be exploited to alleviate environmental pollution problems. The pathways by which a given compound is degraded are determined by the physical, chemical, and microbiological aspects of a particular environment. By understanding the genetic basis of catabolism of xenobiotics, it is possible to improve the efficacy of naturally occurring microorganisms or construct new microorganisms capable of degrading pollutants in soil and aquatic environments more efficiently. Recently a number of genes whose enzyme products have a broader substrate specificity for the degradation of aromatic compounds have been cloned and attempts have been made to construct gene cassettes or synthetic operons comprising these degradative genes. Such gene cassettes or operons can be transferred into suitable microbial hosts for extending and custom designing the pathways for rapid degradation of recalcitrant compounds. Recent developments in designing recombinant microorganisms and hybrid metabolic pathways are discussed.
在本综述中，我们讨论了微生物对氯代烃的降解，重点阐述了脂肪族、芳香族和多环化合物生物降解的生理、生化及遗传基础。许多对环境具有重要意义的异生素都含有卤素，尤其是氯。这些化合物被制造出来并用作农药、增塑剂、油漆和印刷油墨成分、粘合剂、阻燃剂、液压和传热流体、制冷剂、溶剂、切削油添加剂以及纺织助剂。这些有害化学物质通过生产、商业应用和废弃物进入环境。由于它们在食物链中的生物累积以及对地下水的污染，许多物质具有毒性、致突变性或致癌性，从而引发了公共卫生问题。尽管合成化学物质通常难以被生物降解，但微生物已进化出一系列广泛的酶、代谢途径和调控机制，负责分解多种此类化合物。因此，可以利用这种生物降解来缓解环境污染问题。特定化合物的降解途径取决于特定环境的物理、化学和微生物学方面。通过了解异生素分解代谢的遗传基础，有可能提高天然微生物的效能，或构建能够更高效降解土壤和水环境中污染物的新型微生物。最近，一些酶产物对芳香族化合物降解具有更广泛底物特异性的基因已被克隆，并尝试构建包含这些降解基因的基因盒或合成操纵子。此类基因盒或操纵子可转入合适的微生物宿主中，以扩展和定制难降解化合物快速降解的途径。本文还讨论了设计重组微生物和杂交代谢途径方面的最新进展。
