Thermophilic methanotrophs: in hot pursuit

• Published in: FEMS microbiology ecology 2019-09, Vol.95 (9), p.1
• Main Authors: Houghton, Karen M, Carere, Carlo R, Stott, Matthew B, McDonald, Ian R
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Aquatic habitats; Bacteria, Thermophilic; Budgets; Chemical properties; Climate change; Climate effects; Degassing; Ecology; Environmental aspects; Geology; Global climate; Greenhouse effect; Greenhouse gases; High temperature; Landfills; Lithosphere; Magma; Methane; Methanotrophic bacteria; Methanotrophs; Microbiology; Microorganisms; Oxidation; Rice fields; Sewage treatment; Volcanoes; Waste disposal sites; Wastewater treatment
• ISSN: 1574-6941; 0168-6496; 1574-6941
• DOI: 10.1093/femsec/fiz125

ABSTRACT Methane is a potent greenhouse gas responsible for 20–30% of global climate change effects. The global methane budget is ∼500–600 Tg y−1, with the majority of methane produced via microbial processes, including anthropogenic-mediated sources such as ruminant animals, rice fields, sewage treatment facilities and landfills. It is estimated that microbially mediated methane oxidation (methanotrophy) consumes >50% of global methane flux each year. Methanotrophy research has primarily focused on mesophilic methanotrophic representatives and cooler environments such as freshwater, wetlands or marine habitats from which they are sourced. Nevertheless, geothermal emissions of geological methane, produced from magma and lithosphere degassing micro-seepages, mud volcanoes and other geological sources, contribute an estimated 33–75 Tg y−1 to the global methane budget. The aim of this review is to summarise current literature pertaining to the activity of thermophilic and thermotolerant methanotrophs, both proteobacterial (Methylocaldum, Methylococcus, Methylothermus) and verrucomicrobial (Methylacidiphilum). We assert, on the basis of recently reported molecular and geochemical data, that geothermal ecosystems host hitherto unidentified species capable of methane oxidation at higher temperatures. This review summarises data on thermophilic and thermotolerant methanotrophs and proposes that geothermal ecosystems host unrecognised species capable of methane oxidation at high temperatures, based on recently reported data.