Identification and widespread environmental distribution of a gene cassette implicated in anaerobic dichloromethane degradation. (17th January 2022)

• Record Type: Journal Article
• Authors: Murdoch, Robert W.; Chen, Gao; Kara Murdoch, Fadime; Mack, E. Erin; Villalobos Solis, Manuel I.; Hettich, Robert L.; Löffler, Frank E.
• Is Part Of: Global change biology. Volume 28:Number 7(2022)
• Page Start: 2396
• Page End: 2412
• Publication Date: 2022-01-17
• Subjects: anaerobic degradation -- bioremediation -- climate change -- dichloromethane flux -- ozone destruction; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.16068
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: Anthropogenic activities and natural processes release dichloromethane (DCM, methylene chloride), a toxic chemical with substantial ozone‐depleting capacity. Specialized anaerobic bacteria metabolize DCM; however, the genetic basis for this process has remained elusive. Comparative genomics of the three known anaerobic DCM‐degrading bacterial species revealed a homologous gene cluster, designated the methylene chloride catabolism ( mec ) gene cassette, comprising 8–10 genes encoding proteins with 79.6%–99.7% amino acid identities. Functional annotation identified genes encoding a corrinoid‐dependent methyltransferase system, and shotgun proteomics applied to two DCM‐catabolizing cultures revealed high expression of proteins encoded on the mec gene cluster during anaerobic growth with DCM. In a DCM‐contaminated groundwater plume, the abundance of mec genes strongly correlated with DCM concentrations ( R 2 = 0.71–0.85) indicating their potential value as process‐specific bioremediation biomarkers. mec gene clusters were identified in metagenomes representing peat bogs, the deep subsurface, and marine ecosystems including oxygen minimum zones (OMZs), suggesting a capacity for DCM degradation in diverse habitats. The broad distribution of anaerobic DCM catabolic potential infers a role for DCM as an energy source in various environmental systems, and implies that the global DCM flux (i.e., the rate of formation minus the rate of consumption) might be greater than emission measurements suggest. Abstract : Anthropogenic activities and natural processes release dichloromethane (DCM, methylene chloride), a toxic chemical with substantial ozone‐depleting capacity. This study describes the mec gene cluster, implicated in anaerobic DCM degradation. Demonstrated broad environmental distribution suggests that global DCM flux might be greater than emission measurements suggest.