Biodegradation of 3-methyldiphenylether (MDE) by Hydrogenophaga atypical strain QY7-2 and cloning of the methy-oxidation gene mdeABCD.

Qian Yang,Shaowei Dong,Lulu Chen,Jifei Chen,Tianming Cai,Shu Cai

doi:10.1038/srep39270

Qian Yang, Shaowei Dong + Show 4 more

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https://doi.org/10.1038/srep39270

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Abstract

3-Methyldiphenylether (MDE) is an important alkyl-substituted diphenyl ether compound that is widely used as an intermediate in the synthesis of pyrethroid insecticides. An efficient MDE-degrading strain QY7-2, identified as Hydrogenophaga atypical, was isolated from activated sludge for the first time. Strain QY7-2 can utilize MDE as the sole carbon and energy source and completely mineralize MDE. The degradation pathway of MDE was proposed in the strain through metabolites identification. A gene cluster involving in methy-oxidation of MDE was cloned from QY7-2 and expressed in Escherichia coli BL21 (DE3), and the products were purified by SDS-PAGE. The specific activities of the recombinant enzymes MdeAB, MdeC and MdeD were 113.8 ± 3.5, 274.5 ± 6.2 and 673.4 ± 8.7 nmol min−1 mg−1, respectively. These results provide the biochemical and genetic foundation of microbial degradation pathway of MDE and benefit the bioremediation of MDE-contaminated environments.

Highlights

Biodegradation involves the use of living microorganisms to degrade pollutants and is generally considered as a major factor determining the fate of pollutants in the environment[6]
3-Methyldiphenylether (MDE) is an important alkyl-substituted diphenyl ether compound that is widely used as an intermediate in the synthesis of pyrethroid insecticides
The 16S rDNA gene sequence results indicated that strain QY7-2 formed a distinct lineage within the genus Hydrogenophaga (Fig. S1), showed 98.41% similarity to Hydrogenophaga atypical BSB41.8 T

Summary

Introduction

Biodegradation involves the use of living microorganisms to degrade pollutants and is generally considered as a major factor determining the fate of pollutants in the environment[6]. Schmidt reported that a diphenyl ether-degrading bacterium Sphingomonas sp. PH-07 utilizes diphenyl ethers as the sole carbon resource for growth, resulting in phenol and 2-hydroxymuconic acid as the metabolites, after which a cleavage catalysed by dioxygenase gives rise to the formation 2-hydroxy maleic[9]. Sun et al showed biosorption and biodegradation in the removal process of 2, 2, 4, 4-tetrabromodiphenyl ether (BDE-47) using the Pseudomonas stutzeri strain KS001310. Et al.[11] isolated a MDE-degrading strain www.nature.com/scientificreports/. An efficient MDE-degrading strain was isolated from activated sludge and was identified as Hydrogenophaga atypical. Three metabolites of MDE were identified, and the novel gene, mdeABCD, which encodes the enzymes and catalyses the methy-oxidation reaction, was cloned and functionally expressed in E. coli BL21 (DE3)

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