Degradation of the herbicide dicamba by two sphingomonads via different O-demethylation mechanisms. (October 2015)

• Record Type: Journal Article
• Authors: Yao, Li; Jia, Xingjun; Zhao, Jiadong; Cao, Qin; Xie, Xiangting; Yu, Linlu; He, Jian; Tao, Qing
• Is Part Of: International biodeterioration & biodegradation. Volume 104(2015)
• Page Start: 324
• Page End: 332
• Publication Date: 2015-10
• Subjects: Dicamba -- Microbial degradation -- Sphingomonads -- O-demethylation -- Tetrahydrofolic acid-dependent O-demethylase; Biodegradation -- Periodicals; Bioremediation -- Periodicals; Biodegradation -- Periodicals; Biodégradation -- Périodiques; Biorestauration -- Périodiques; Electronic journals; 620.11223
• DOI: 10.1016/j.ibiod.2015.06.016
• Languages: English
• ISSNs: 0964-8305

Abstract

Abstract: Dicamba, a chlorinated benzoic acid herbicide, is widely used to control broadleaf weeds. In this study, two dicamba-degrading sphingomonads Sphingobium sp. Ndbn-10 and Sphingomonas sp. Ndbn-20 were isolated from activated sludge and compost samples, respectively. Both isolates could completely degrade and utilize dicamba, but strain Ndbn-10 possessed relatively higher dicamba degradation efficiency than strain Ndbn-20. The degradation of dicamba in both isolates was initiated by O- demethylation to generate 3, 6-dichlorosalicylic acid (DCSA) but through different mechanisms. For Sphingobium sp. Ndbn-10, O- demethylation is catalyzed by a NADH-dependent dicamba monooxygenase (DMO), whereas in Sphingomonas sp. Ndbn-20, a tetrahydrofolic acid (THF)-dependent O- demethylase is responsible for the O- demethylation. Our results suggest that sphingomonads can rapidly and efficiently adapt to degrading dicamba through the evolution of different metabolic pathway mechanisms and highlight a novel THF-dependent dicamba O- demethylation mechanism in bacteria. Highlights: Two dicamba-degrading sphingomonads were isolated. The dicamba O -demethylation mechanisms in the two sphingomonads are different: in Sphingobium sp. Ndbn-10, the O- demethylase of dicamba is catalyzed by dicamba monooxygenase (DMO); whereas in Sphingomonas sp. Find a THF-dependent O- demethylase of dicamba-degrading in Sphingomonas sp. Ndbn-20.