Comparative genomic analysis of iprodione-degrading Paenarthrobacter strains reveals the iprodione catabolic molecular mechanism in Paenarthrobacter sp. strain YJN-5.

Degradation of the fungicide iprodione by the Paenarthrobacter sp. strain YJN-5 is initiated via hydrolysis of its N1 amide bond to form N-(3,5-dichlorophenyl)-2,4-dioxoimidazolidine. In this study, another iprodione-degrading strain, Paenarthrobacter sp. YJN-D, which harbours the same metabolic pathway as strain YJN-5 was isolated and characterized. The genes that encode the conserved iprodione catabolic pathway were identified based on comparative analysis of the genomes of the two iprodione-degrading Paenarthrobacter sp. and subsequent experimental validation. These genes include an amidase gene, ipaH (previously reported in AEM e01150-18); a deacetylase gene, ddaH, which is responsible for hydantoin ring cleavage of N-(3,5-dichlorophenyl)-2,4-dioxoimidazolidine, and a hydrolase gene, duaH, which is responsible for cleavage of the urea side chain of (3,5-dichlorophenylurea)acetic acid, thus yielding 3,5-dichloroaniline as the end product. These iprodione-catabolic genes are distributed on three plasmids in strain YJN-5 and are highly conserved between the two iprodione-degrading Paenarthrobacter strains. However, only the ipaH gene is flanked by a mobile genetic element. Two iprodione degradation cassettes bearing ipaH-ddaH-duaH were constructed and expressed in strains Pseudomonas putida KT2440 and Bacillus subtilis SCK6 respectively. Our findings enhance the current understanding of the microbial degradation mechanism of iprodione.