A bifunctional enzyme belonging to cytochrome P450 family involved in the O-dealkylation and N-dealkoxymethylation toward chloroacetanilide herbicides in Rhodococcus sp. B2

Abstract Background The chloroacetamide herbicides pretilachlor is an emerging pollutant. Due to the large amount of use, its presence in environment threatens human health. However, molecular mechanism degradation remains unknown. Results Now, Rhodococcus sp. B2 was isolated from rice field and shown degrade pretilachlor. maximum efficiency (86.1%) observed at a culture time 5 d, initial substrate concentration 50 mg/L, pH 6.98, 30.1 °C. One novel metabolite N -hydroxyethyl-2-chloro- -(2, 6-diethyl-phenyl)-acetamide identified by gas chromatography-mass spectrometry (GC–MS). Draft genome comparison demonstrated that 32,147-bp DNA fragment, harboring gene cluster ( EthRABCD ), absent mutant strain TB2 which could not Eth cluster, encodes AraC/XylS family transcriptional regulator (EthR ferredoxin reductase (EthA cytochrome P450 monooxygenase (EthB (EthC ) 10-kDa protein unknown function (EthD ). Complementation with EthABCD EthABD , but EthABC restored ability herbicides. Subsequently, codon optimization performed, after optimized components were separately expressed Escherichia coli purified using Ni-affinity chromatography. A mixture or catalyzed N- dealkoxymethylation alachlor, acetochlor, butachlor, propisochlor O -dealkylation pretilachlor, revealing EthD acted as B2. displayed maximal activity 30 °C 7.5. Conclusions This first report oxygenase catalyzing propisochlor, respectively. And results present study provide microbial resource for remediation herbicides-contaminated sites.