Degradation of 3,5,6-trichloro-2-pyridinol by a microbial consortium in dryland soil with anaerobic incubation

Biodegradation of 3,5,6-trichloro-2-pyridinol (TCP) in drylands is an important biological process of detoxification. Flooding in drylands can result in the formation of anaerobic habitats. However, little is known about the microbial metabolism of TCP in dryland soil under anaerobic conditions. Here, chlorpyrifos-contaminated dryland soil was incubated to enrich the TCP-degrading microbial consortium under anaerobic conditions. Chloridion and CO2 were released with TCP degradation, and the enrichment cultures of dryland soil could metabolize 97% of TCP (100mg/L) within 20h. Both reductive and hydrolysis dechlorination mechanisms were involved in TCP biodegradation under anaerobic conditions. Bacterial taxonomic analysis revealed that the aerobic TCP-degrading bacteria Ochrobactrum and dechlorination bacteria Delftia were the dominant genera. Anaerobic and facultative bacteria; i.e., Bacteroides, Bacillus, and Cupriavidus had lower relative abundances, but they were significantly enriched following treatment with TCP. These results indicate that the enrichment cultures of dryland soil dominated by aerobic bacteria could dechlorinate and degrade TCP under anaerobic conditions.