Biodegradation of chloroacetamide herbicides by Paracoccus sp. FLY-8 in vitro.
Biodegradation of chloroacetamide herbicides by Paracoccus sp. FLY-8 in vitro.
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DOI：
10.1021/jf104695g
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发表时间：
2011-03
影响因子：
6.1
通讯作者：
Jun Zhang;Jin-Wei Zheng;B. Liang;Chenghong Wang;Shu Cai;Y. Ni;Jian He;Shun-Peng Li
中科院分区：
文献类型：
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作者：
Jun Zhang;Jin-Wei Zheng;B. Liang;Chenghong Wang;Shu Cai;Y. Ni;Jian He;Shun-Peng Li
从稻田土壤中分离到一株丁草胺降解菌，命名为Fly-8，经鉴定为Paracoccus sp.菌株Fly-8能降解并利用6种氯乙酰胺类除草剂作为碳源生长，降解速率大小顺序为甲草胺>乙草胺>异丙草胺>丁草胺>异丙草胺。首先分析了氯乙酰胺类除草剂的分子结构对微生物降解率的影响，结果表明，烷氧基甲基侧链与烷氧基乙基侧链的取代大大降低了除草剂的降解效率；酰胺氮的烷氧甲基长度对这些除草剂的生物降解性有显著影响：烷基越长，降解效率越慢。苯基烷基取代基对降解效率无明显影响。根据代谢物鉴定和酶测定结果，阐明了丁草胺完全矿化的途径。丁草胺通过部分C-脱烷基化降解为甲草胺，再通过N-脱烷基化转化为2-氯-N-(2，6-二甲基苯基)乙酰胺，再转化为2，6-二乙基苯胺，再通过代谢物苯胺和邻苯二酚进一步降解，邻苯二酚通过邻位裂解途径被氧化。这项研究突出了菌株Fly-8在氯乙酰胺除草剂及其代谢物污染环境中的原位生物修复方面的重要潜在用途。
A butachlor-degrading strain, designated FLY-8, was isolated from rice field soil and was identified as Paracoccus sp. Strain FLY-8 could degrade and utilize six chloroacetamide herbicides as carbon sources for growth, and the degradation rates followed the order alachlor > acetochlor > propisochlor > butachlor > pretilachlor > metolachlor. The influence of molecular structure of the chloroacetamide herbicides on the microbial degradation rate was first analyzed; the results indicated that the substitutions of alkoxymethyl side chain with alkoxyethyl side chain greatly reduced the degradation efficiencies; the length of amide nitrogen's alkoxymethyl significantly affected the biodegradability of these herbicides: the longer the alkyl was, the slower the degradation efficiencies occurred. The phenyl alkyl substituents have no obvious influence on the degradation efficiency. The pathway of butachlor complete mineralization was elucidated on the basis of the results of metabolite identification and enzyme assays. Butachlor was degraded to alachlor by partial C-dealkylation and then converted to 2-chloro-N-(2,6-dimethylphenyl)acetamide by N-dealkylation, which subsequently transformed to 2,6-diethylaniline, which was further degraded via the metabolites aniline and catechol, and catechol was oxidized through an ortho-cleavage pathway. This study highlights an important potential use of strain FLY-8 for the in situ bioremediation of chloroacetamide herbicides and their metabolite-contaminated environment.