Electrostimulated bio-dechlorination of a PCB mixture (Aroclor 1260) in a marine-originated dechlorinating culture

Dongdong Zhang; Xinkai Li; Chunfang Zhang; Zhixing Xiao; Yanhong Li; Yanpeng Liang; Hongyue Dang

doi:10.1016/j.envpol.2021.118157

Electrostimulated bio-dechlorination of a PCB mixture (Aroclor 1260) in a marine-originated dechlorinating culture

Environ Pollut. 2021 Dec 15:291:118157. doi: 10.1016/j.envpol.2021.118157. Epub 2021 Sep 10.

Authors

Dongdong Zhang¹, Xinkai Li², Chunfang Zhang³, Zhixing Xiao⁴, Yanhong Li⁵, Yanpeng Liang⁵, Hongyue Dang⁶

Affiliations

¹ Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, Zhoushan, 316021, Zhejiang, China; Ocean Research Center of Zhoushan, Zhejiang University, Zhoushan, 316021, Zhejiang, China; State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, And Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen, 361102, Fujian, China.
² Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, Zhoushan, 316021, Zhejiang, China.
³ Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, Zhoushan, 316021, Zhejiang, China; The Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, Guilin, 541006, Guangxi, China.
⁴ College of Urban Construction, Nanjing Tech University, Nanjing, 211816, China.
⁵ The Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, Guilin, 541006, Guangxi, China.
⁶ State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, And Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen, 361102, Fujian, China. Electronic address: DangHY@xmu.edu.cn.

PMID: 34530245
DOI: 10.1016/j.envpol.2021.118157

Abstract

Aroclor 1260, a commercial polychlorinated biphenyl (PCB) mixture, is highly recalcitrant to biotransformation. A negatively polarized cathode (-0.35 V vs. standard hydrogen electrode) was applied for the first time to a marine-origin PCB dechlorinating culture that substantially increased the microbial dechlorination rate of Aroclor 1260 (from 8.6 to 11.6 μM Cl^- d^-1); meta-chlorine removal was stimulated and higher proportions of tetra-CBs (43.2-46.6%), the predominant dechlorination products, were observed compared to the open circuit conditions (23.7-25.1%). The dechlorination rate was further enhanced (14.1 μM Cl^- d^-1) by amendment with humin as a solid-phase redox mediator. After the suspension culture was renewed using an anaerobic medium, dechlorination activity was effectively maintained solely by cathodic biofilms, where cyclic voltammetry results indicated their redox activity. Electric potential had a significant effect on microbial community structure in the cathodic biofilm, where a greater abundance of Dehalococcoides (2.59-3.02%), as potential dechlorinators, was observed compared to that in the suspension culture (0.41-0.55%). Moreover, Dehalococcoides adhering to the cathode showed a higher chlorine removal rate than in the suspension culture. These findings provide insights into the dechlorination mechanism of cathodic biofilms involving Dehalococcoides for PCB mixtures and extend the application prospects of bioremediation to PCB contamination in the natural environment.

Keywords: Cathodic biofilm; Commercial PCB mixture; Dehalococcoides; Humin; PCB dechlorination Pathway.

MeSH terms

Aroclors
Biodegradation, Environmental
Chlorine
Chloroflexi*
Geologic Sediments
Polychlorinated Biphenyls*

Substances

Aroclors
aroclor 1260
Chlorine
Polychlorinated Biphenyls