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Dehalogenation of halogenated benzoic acids in denitrifying bacteria

反硝化细菌中卤代苯甲酸的脱卤

基本信息

批准号：
191845302
负责人：
Professor Dr. Matthias Boll
金额：
--
依托单位：
Forschungsschwerpunkt Mikrobiologie
依托单位国家：
德国
项目类别：
Research Units
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/191845302?language=en
关键词：
Dehalogenation halogenated benzoic acids denitrifying

项目摘要

Halogenated aromatics represent a widely distributed class of environmentally relevant compounds, which can be biologically degraded under both aerobic and anaerobic conditions. The anaerobic degradation has usually been associated with membrane-bound reductive dehalogenases, corrinoid-containing key enzymes of anaerobic organohalide respiration. In contrast, the complete oxidative degradation of halobenzoates in anaerobes has been reported in denitrifying, sulfate-reducing, Fe(III)-respiring and in anaerobic phototrophic bacteria. Although initial evidence has been obtained that in Rhodopseudomonas palustris the 3-Cl-benzoate degradation pathway proceeds via CoA-esters, including a reductive dehalogenation step, the dehalogenation reaction has thus far not been demonstrated in vitro. Reductive removal of the halogen atom from halobenzoyl-CoAs may be accomplished by a novel class of dehalogenases or by dearomatizing benzoyl-CoA reductases. In this project we will study the degradation of various halobenzoates in the denitrifying model organisms Thauera chlorobenzoica and Azoarcus evansii. The major objectives are: (i) determination of the substrate/product of the dehalogenation reactions by CoA-ester metabolome analysis and by the in vitro assays; (ii) characterization of the enzymatic dehalogenation process (kinetics, mechanism, stereochemical course, etc.); (iii) isolation/characterization of key enzymes involved in halobenzoate catabolism; and (iv) the determination of the minimal enzymatic prerequisites for growth on halobenzoates.

卤代芳烃是一类分布广泛的环境相关化合物，在好氧和厌氧条件下都能被生物降解。厌氧降解通常与膜结合的还原脱卤酶有关，这些酶是有机卤化物厌氧呼吸的关键酶，含有皮质激素。相比之下，卤代苯甲酸盐在厌氧菌中的完全氧化降解是通过反硝化、硫酸盐还原、Fe(III)呼吸和厌氧光营养细菌来实现的。虽然已有初步证据表明沼泽红假单胞菌中3-氯-苯甲酸的降解途径是通过辅酶A-酯进行的，包括还原脱卤化步骤，但到目前为止还没有在体外证明脱卤化反应。从卤代苯甲酰辅酶A中还原脱除卤素原子可以通过一类新型的脱卤酶或通过去芳构化苯甲酰辅酶A还原酶来完成。在本项目中，我们将研究各种卤代苯甲酸盐在反硝化模式生物氯苯和固氮藻中的降解。主要目标是：(I)通过CoA-酯代谢组分析和体外分析确定脱卤化反应的底物/产物；(Ii)酶法脱卤化过程的表征(动力学、机理、立体化学过程等)；(Iii)参与卤代苯甲酸分解代谢的关键酶的分离/表征；以及(Iv)在卤代苯甲酸盐上生长的最低酶先决条件的确定。