Methanotrophs

Discoveries, Environmental Relevance, and a Perspective on Current and Future Applications

authored by

Simon Guerrero-Cruz, Annika Vaksmaa, Marcus A Horn, Helge Niemann, Maite Pijuan, Adrian Ho

Abstract

Methane is the final product of the anaerobic decomposition of organic matter. The conversion of organic matter to methane (methanogenesis) as a mechanism for energy conservation is exclusively attributed to the archaeal domain. Methane is oxidized by methanotrophic microorganisms using oxygen or alternative terminal electron acceptors. Aerobic methanotrophic bacteria belong to the phyla Proteobacteria and Verrucomicrobia, while anaerobic methane oxidation is also mediated by more recently discovered anaerobic methanotrophs with representatives in both the bacteria and the archaea domains. The anaerobic oxidation of methane is coupled to the reduction of nitrate, nitrite, iron, manganese, sulfate, and organic electron acceptors (e.g., humic substances) as terminal electron acceptors. This review highlights the relevance of methanotrophy in natural and anthropogenically influenced ecosystems, emphasizing the environmental conditions, distribution, function, co-existence, interactions, and the availability of electron acceptors that likely play a key role in regulating their function. A systematic overview of key aspects of ecology, physiology, metabolism, and genomics is crucial to understand the contribution of methanotrophs in the mitigation of methane efflux to the atmosphere. We give significance to the processes under microaerophilic and anaerobic conditions for both aerobic and anaerobic methane oxidizers. In the context of anthropogenically influenced ecosystems, we emphasize the current and potential future applications of methanotrophs from two different angles, namely methane mitigation in wastewater treatment through the application of anaerobic methanotrophs, and the biotechnological applications of aerobic methanotrophs in resource recovery from methane waste streams. Finally, we identify knowledge gaps that may lead to opportunities to harness further the biotechnological benefits of methanotrophs in methane mitigation and for the production of valuable bioproducts enabling a bio-based and circular economy.

Organisation(s)

Institute of Microbiology

External Organisation(s)

Catalan Institute for Water Research (ICRA)
Royal Netherlands Institute for Sea Research - NIOZ

Type

Review article

Journal

Frontiers in microbiology

Volume

12

ISSN

1664-302X

Publication date

14.05.2021

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Microbiology, Microbiology (medical)

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy, SDG 8 - Decent Work and Economic Growth, SDG 12 - Responsible Consumption and Production, SDG 13 - Climate Action

Electronic version(s)

https://doi.org/10.3389/fmicb.2021.678057 (Access: Open)