Active coexistence of the novel gammaproteobacterial methanotroph ‘Ca. Methylocalor cossyra’ CH1 and verrucomicrobial methanotrophs in acidic, hot geothermal soil

• Published in: Environmental microbiology Vol. 26; no. 3; pp. e16602 - n/a
• Main Authors: Liu, Changqing, Schmitz, Rob A., Pol, Arjan, Hogendoorn, Carmen, Verhagen, Daniël, Peeters, Stijn H., Alen, Theo A., Cremers, Geert, Mesman, Rob A., Op den Camp, Huub J. M.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.03.2024; Wiley Subscription Services, Inc
• Subjects: Acidic soils; Acids; Calvin cycle; Candidatus Methylocalor cossyra; Carbon dioxide; Coexistence; Dehydrogenases; Ecosystem; Ecosystems; Gases; Genes; Genomes; Hydrogen sulfide; Methane; Methanotrophic bacteria; Microorganisms; pH effects; Phylogenetics; Phylogeny; Proteobacteria; Soil; Soil Microbiology; Soils
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/1462-2920.16602

Terrestrial geothermal ecosystems are hostile habitats, characterized by large emissions of environmentally relevant gases such as CO2, CH4, H2S and H2. These conditions provide a niche for chemolithoautotrophic microorganisms. Methanotrophs of the phylum Verrucomicrobia, which inhabit these ecosystems, can utilize these gases and grow at pH levels below 1 and temperatures up to 65°C. In contrast, methanotrophs of the phylum Proteobacteria are primarily found in various moderate environments. Previously, novel verrucomicrobial methanotrophs were detected and isolated from the geothermal soil of the Favara Grande on the island of Pantelleria, Italy. The detection of pmoA genes, specific for verrucomicrobial and proteobacterial methanotrophs in this environment, and the partially overlapping pH and temperature growth ranges of these isolates suggest that these distinct phylogenetic groups could coexist in the environment. In this report, we present the isolation and characterization of a thermophilic and acid‐tolerant gammaproteobacterial methanotroph (family Methylococcaceae) from the Favara Grande. This isolate grows at pH values ranging from 3.5 to 7.0 and temperatures from 35°C to 55°C, and diazotrophic growth was demonstrated. Its genome contains genes encoding particulate and soluble methane monooxygenases, XoxF‐ and MxaFI‐type methanol dehydrogenases, and all enzymes of the Calvin cycle. For this novel genus and species, we propose the name ‘Candidatus Methylocalor cossyra’ CH1. The genome and ecophysiology of a novel gammaproteobacterial methanotroph isolated from geothermal soil were analysed. This bacterium can grow at pH values as low as pH 3.5 and temperatures up to 55°C and coexists with verrucomicrobial methanotrophs in the hot volcanic soil on Pantelleria island.