A Synergistic Consortium Involved in -Dichlorprop Degradation As Revealed by DNA Stable Isotope Probing and Metagenomic Analysis

-Dichlorprop, a commonly used phenoxyalkanoic acid herbicide, is frequently detected in environments and poses threats to environmental safety and human health. Microbial consortia are thought to play key roles in -dichlorprop degradation. However, the compositions of the microbial consortia involved in -dichlorprop degradation remain largely unknown. In this study, DNA stable isotope probing (SIP) and metagenomic analysis were integrated to reveal the key microbial consortium responsible for -dichlorprop degradation in a -dichlorprop-degrading enrichment. OTU340 ( sp.) and OTU348 ( sp.) were significantly enriched in the -[C]dichlorprop-labeled heavy DNA fractions. A -dichlorprop degrader, sp. strain L3, was isolated from the enrichment by a traditional enrichment method but with additional supplementation of the antibiotic ciprofloxacin, which was instructed by metagenomic analysis of the associations between -dichlorprop degraders and antibiotic resistance genes. As revealed by functional profiling of the metagenomes of the heavy DNA, the genes and , involved in the initial degradation of the ()- and ()-enantiomers of dichlorprop, respectively, were mostly taxonomically assigned to species, indicating that species might harbor novel dichlorprop-degrading genes. In addition, taxonomically diverse bacterial genera such as , , Pseudomonas, and were presumed to synergistically cooperate with the key degraders for enhanced degradation of -dichlorprop. Understanding of the key microbial consortium involved in the degradation of the phenoxyalkanoic acid herbicide -dichlorprop is pivotal for design of synergistic consortia used for enhanced bioremediation of herbicide-contaminated sites. However, the composition of the microbial consortium and the interactions between community members during the biodegradation of -dichlorprop are unclear. In this study, DNA-SIP and metagenomic analysis were integrated to reveal that the metabolite 2,4-dichlorophenol degraders , , Pseudomonas, and synergistically cooperated with the key degraders / for enhanced degradation of -dichlorprop. Our study provides new insights into the synergistic degradation of -dichlorprop at the community level and implies the existence of novel degrading genes for -dichlorprop in nature.