Insights into the biodegradation process of 2,4,5-trichlorophenoxyacetic acid under anaerobic condition

• Published in: Ecological processes Vol. 13; no. 1; p. 63
• Main Authors: Li, Xiuying, Lv, Yan, Wang, Yuanzhi, Zhang, Zhipeng, Wang, Jingjing, Jin, Huijuan, Zhou, Tongyue, Cui, Yiru, Yang, Yi, Yan, Jun
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2024; Springer Nature B.V; SpringerOpen
• Subjects: 2,4,5-T; 2,4,5-Trichlorophenoxyacetic acid; 3-chlorophenol; Acetobacterium; Anaerobic conditions; Anaerobic degradation; Anaerobic microorganisms; Anaerobic processes; Anoxic conditions; Aquifers; Bacteroides; Biodegradation; Chlorophenol; Clostridium; Dechlorination; Degradation; Dehalobacter; Drinking water; Earth and Environmental Science; Environment; Groundwater; Herbicides; human health; intermediate product; Leaching; methanogens; Methanosaeta; Microbiology; Microorganisms; Migration and transformation processes of pollutants amidst technology advancement; Mineralization; Oxidation; phenol; Phenols; Reductive dechlorination; Smithella; soil; Soil chemistry; Syntrophic metabolism; toxicity; Anaerobic degradation; Syntrophic metabolism; 2,4,5-Trichlorophenoxyacetic acid; Reductive dechlorination
• ISSN: 2192-1709; 2192-1709
• DOI: 10.1186/s13717-024-00545-1

Background Chlorophenoxy compounds represent a group of selective herbicides widely used around the world. Chlorophenoxy herbicides are toxic, chemically stable, and can migrate into groundwater through soil leaching, posing a significant threat to drinking water safety and human health. Chlorophenoxy herbicides in groundwater aquifers are subject to anaerobic processes; however, the pathway and microbiology involved in the attenuation of chlorophenoxy herbicides under anaerobic condition are largely unknown. Here, the anaerobic degradation process of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), a typical chlorophenoxy herbicide, was investigated. Results The initial 52.5 ± 2.3 μM 2,4,5-T was completely degraded by a sediment-derived microbial consortium, with 3,4-dichlorophenol, 2,5-dichlorophenol, 3-chlorophenol (3-CP) and phenol being identified as the intermediate products. Reductive dechlorination of 3-CP to phenol and the subsequent elimination of phenol were the key transformation steps in the overall degradation process of 2,4,5-T. Amplicon sequencing suggested that Dehalobacter , Sulfuricurvum , Bacteroides , Acetobacterium , and Clostridium sensu stricto 7 might contribute to the transformation of 2,4,5-T to phenol, and Smithella , Syntrophorhabdus , Methanofollis and Methanosaeta likely cooperated to accomplish the complete mineralization of phenol. Conclusions This study reported the anaerobic degradation of 2,4,5-T via reductive dechlorination and the subsequent syntrophic metabolization of phenol, an intermediate product transformed from 2,4,5-T. Dehalobacter was identified as the organohalide-respiring population catalyzing the reductive dechlorination reaction. Syntrophorhabdus and methanogenic populations were likely involved in anaerobic phenol oxidation and facilitated the complete mineralization of 2,4,5-T.