Metagenomic-and cultivation-based exploration of anaerobic chloroform biotransformation in hypersaline sediments as natural source of chloromethanes

Peng Peng, Yue Lu, Tom N.P. Bosma, Ivonne Nijenhuis, Bart Nijsse, Sudarshan A. Shetty, Alexander Ruecker, Alexander Umanets, Javier Ramiro-Garcia, Andreas Kappler, Detmer Sipkema, Hauke Smidt, Siavash Atashgahi*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Chloroform (CF) is an environmental contaminant that can be naturally formed in various environments ranging from forest soils to salt lakes. Here we investigated CF removal potential in sediments obtained from hypersaline lakes in Western Australia. Reductive dechlorination of CF to dichloromethane (DCM) was observed in enrichment cultures derived from sediments of Lake Strawbridge, which has been reported as a natural source of CF. No CF removal was observed in abiotic control cultures without artificial electron donors, indicating biotic CF dechlorination in the enrichment cultures. Increasing vitamin B12 concentration from 0.04 to 4 µM in enrichment cultures enhanced CF removal and reduced DCM formation. In cultures amended with 4 µM vitamin B12 and13C labelled CF, formation of13CO2 was detected. Known organohalide-respiring bacteria and reductive dehalogenase genes were neither detected using quantitative PCR nor metagenomic analysis of the enrichment cultures. Rather, members of the order Clostridiales, known to co-metabolically transform CF to DCM and CO2, were detected. Accordingly, metagenome-assembled genomes of Clostridiales encoded enzymatic repertoires for the Wood-Ljungdahl pathway and cobalamin biosynthesis, which are known to be involved in fortuitous and nonspecific CF transformation. This study indicates that hypersaline lake microbiomes may act as a filter to reduce CF emission to the atmosphere.

Original languageEnglish
Article number665
JournalMicroorganisms
Volume8
Issue number5
DOIs
Publication statusPublished - May 2020

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Keywords

  • Biotransformation
  • Chloroform
  • Hypersaline lakes
  • Metagenome

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