How Pseudomonas conducts reductive dechlorination of 2,4,6-trichlorophenol: Insights into metabolic performance and organohalide respiration process

Xueqi Chen; Zhiling Li; Zimeng Zhang; Jun Nan; Guanshu Zhao; Shih-Hsin Ho; Bin Liang; Aijie Wang

doi:10.1016/j.watres.2024.123014

How Pseudomonas conducts reductive dechlorination of 2,4,6-trichlorophenol: Insights into metabolic performance and organohalide respiration process

Water Res. 2024 Dec 19:273:123014. doi: 10.1016/j.watres.2024.123014. Online ahead of print.

Authors

Xueqi Chen¹, Zhiling Li², Zimeng Zhang¹, Jun Nan¹, Guanshu Zhao¹, Shih-Hsin Ho¹, Bin Liang³, Aijie Wang⁴

Affiliations

¹ State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, PR China.
² State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, PR China. Electronic address: lzlhit@163.com.
³ State Key Laboratory of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen, 518055, PR China.
⁴ State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, PR China; State Key Laboratory of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen, 518055, PR China. Electronic address: waj0578@hit.edu.cn.

PMID: 39719803
DOI: 10.1016/j.watres.2024.123014

Abstract

Organohalide-respiring bacteria (OHRB) play a key role in facilitating the detoxification of halogenated organics, but their slow growth and harsh growth conditions often limit their application in field remediation. In this study, we investigated the metabolic performance and organohalide respiration process of a non-obligate OHRB, Pseudomonas sp. CP-1, demonstrating favorable anaerobic reductive dechlorination ability of 2,4,6-trichlorophenol to 4-chlorophenol with a removal rate constant (k) of 0.46 d^-1. Due to its facultative anaerobic nature, strain CP-1 exhibited unique metabolic properties. In aerobic conditions, strain CP-1 preferentially utilized oxygen for rapid proliferation, and anaerobic reductive dechlorination was initiated once the oxygen was depleted. The aerobic proliferation facilitated the subsequent reductive dechlorination process. Through multi-tool analysis, a modified tricarboxylic acid cycle was proposed to be linked to organohalide respiration when acetate served as the sole carbon source. A predictive model for the electron transport chain (ETC) for reductive dechlorination was constructed, with complex Ⅰ, complex Ⅱ, ubiquinone, complex Fix (flavoprotein), and reductive dehalogenase (RDase) as the major components. A specific RDase facilitating reductive dechlorination was identified. It shared a 64.35 % amino acid similarity with biochemically characterized RDases and was designated CprA-2. Its ortho-dechlorination catalytic process was proposed through molecular docking. The discovery of highly adaptable Pseudomonas with favorable dechlorination activity and the elucidation of its metabolic properties provide valuable insights into the understanding of non-obligate OHRBs and their application regulation.

Keywords: Electron transport chain model; Metabolic performance; Organohalide respiration; Pseudomonas; Reductive dehalogenase.