Methanol consumption drives the bacterial chloromethane sink in a forest soil. Issue 11 (November 2018)

• Record Type: Journal Article
• Authors: Chaignaud, Pauline; Morawe, Mareen; Besaury, Ludovic; Kröber, Eileen; Vuilleumier, Stéphane; Bringel, Françoise; Kolb, Steffen
• Is Part Of: ISME journal. Volume 12:Issue 11(2018)
• Page Start: 2681
• Page End: 2693
• Publication Date: 2018-11
• Subjects: Microbial ecology -- Periodicals; 579.1705
• DOI: 10.1038/s41396-018-0228-4
• Languages: English
• ISSNs: 1751-7362

Abstract

Abstract Halogenated volatile organic compounds (VOCs) emitted by terrestrial ecosystems, such as chloromethane (CH3 Cl), have pronounced effects on troposphere and stratosphere chemistry and climate. The magnitude of the global CH3 Cl sink is uncertain since it involves a largely uncharacterized microbial sink. CH3 Cl represents a growth substrate for some specialized methylotrophs, while methanol (CH3 OH), formed in much larger amounts in terrestrial environments, may be more widely used by such microorganisms. Direct measurements of CH3 Cl degradation rates in two field campaigns and in microcosms allowed the identification of top soil horizons (i.e., organic plus mineral A horizon) as the major biotic sink in a deciduous forest. Metabolically active members ofAlphaproteobacteria andActinobacteria were identified by taxonomic and functional gene biomarkers following stable isotope labeling (SIP) of microcosms with CH3 Cl and CH3 OH, added alone or together as the [13 C]-isotopologue. Well-studied reference CH3 Cl degraders, such asMethylobacterium extorquens CM4, were not involved in the sink activity of the studied soil. Nonetheless, only sequences of thecmuA chloromethane dehalogenase gene highly similar to those of known strains were detected, suggesting the relevance of horizontal gene transfer for CH3 Cl degradation in forest soil. Further, CH3 Cl consumption rate increased in the presence of CH3 OH. Members ofAlphaproteobacteria andActinobacteria were also13 C-labeled upon [13 C]-CH3 OH amendment. These findings suggest that key bacterial CH3 Cl degraders in forest soil benefit from CH3 OH as an alternative substrate. For soil CH3 Cl-utilizing methylotrophs, utilization of several one-carbon compounds may represent a competitive advantage over heterotrophs that cannot utilize one-carbon compounds.