13 C ‐chloromethane incubations provide evidence for novel bacterial chloromethane degraders in a living tree fern

• Published in: Environmental microbiology Vol. 23; no. 8; pp. 4450 - 4465
• Main Authors: Kröber, Eileen, Wende, Sonja, Kanukollu, Saranya, Buchen‐Tschiskale, Caroline, Besaury, Ludovic, Keppler, Frank, Vuilleumier, Stéphane, Kolb, Steffen, Bringel, Françoise
• Format: Journal Article
• Language: English
• Published: Society for Applied Microbiology and Wiley-Blackwell 01.08.2021
• Subjects: Bacteriology; Biodiversity; Biodiversity and Ecology; Environmental Sciences; Life Sciences; Microbiology and Parasitology; Systematics, Phylogenetics and taxonomy
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/1462-2920.15638

Summary Chloromethane (CH 3 Cl) is the most abundant halogenated volatile organic compound in the atmosphere and contributes to stratospheric ozone depletion. CH 3 Cl has mainly natural sources such as emissions from vegetation. In particular, ferns have been recognized as strong emitters. Mitigation of CH 3 Cl to the atmosphere by methylotrophic bacteria, a global sink for this compound, is likely underestimated and remains poorly characterized. We identified and characterized CH 3 Cl‐degrading bacteria associated with intact and living tree fern plants of the species Cyathea australis by stable isotope probing (SIP) with 13 C‐labelled CH 3 Cl combined with metagenomics. Metagenome‐assembled genomes (MAGs) related to Methylobacterium and Friedmanniella were identified as being involved in the degradation of CH 3 Cl in the phyllosphere, i.e., the aerial parts of the tree fern, while a MAG related to Sorangium was linked to CH 3 Cl degradation in the fern rhizosphere. The only known metabolic pathway for CH 3 Cl degradation, via a methyltransferase system including the gene cmuA , was not detected in metagenomes or MAGs identified by SIP. Hence, a yet uncharacterized methylotrophic cmuA ‐independent pathway may drive CH 3 Cl degradation in the investigated tree ferns.