Bark-dwelling methanotrophic bacteria decrease methane emissions from trees

• Published in: Nature communications 2021-04, Vol.12 (1), p.2127-2127, Article 2127
• Main Authors: Jeffrey, Luke C., Maher, Damien T., Chiri, Eleonora, Leung, Pok Man, Nauer, Philipp A., Arndt, Stefan K., Tait, Douglas R., Greening, Chris, Johnston, Scott G.
• Format: Article
• Language: English
• Subjects: 45/77; 45/91; 631/326/41/2529; 631/449/2668; 704/106/47/4113; 704/47/4113; Bacteria; Bark; Carbon Cycle; Carbon dioxide; Emissions; Greenhouse gases; Humanities and Social Sciences; Melaleuca - metabolism; Melaleuca - microbiology; Methane; Methane - metabolism; Methanotrophic bacteria; Methylococcaceae - metabolism; Microbial activity; Microbiota - physiology; Microorganisms; multidisciplinary; Oxidation; Oxidation-Reduction; Photosynthesis; Plant Bark - metabolism; Plant Bark - microbiology; Science; Science (multidisciplinary); Trees; Trees - metabolism; Trees - microbiology
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-22333-7

Tree stems are an important and unconstrained source of methane, yet it is uncertain whether internal microbial controls (i.e. methanotrophy) within tree bark may reduce methane emissions. Here we demonstrate that unique microbial communities dominated by methane-oxidising bacteria (MOB) dwell within bark of Melaleuca quinquenervia , a common, invasive and globally distributed lowland species. In laboratory incubations, methane-inoculated M. quinquenervia bark mediated methane consumption (up to 96.3 µmol m −2 bark d −1 ) and reveal distinct isotopic δ 13 C-CH 4 enrichment characteristic of MOB. Molecular analysis indicates unique microbial communities reside within the bark, with MOB primarily from the genus Methylomonas comprising up to 25 % of the total microbial community. Methanotroph abundance was linearly correlated to methane uptake rates (R 2  = 0.76, p  = 0.006). Finally, field-based methane oxidation inhibition experiments demonstrate that bark-dwelling MOB reduce methane emissions by 36 ± 5 %. These multiple complementary lines of evidence indicate that bark-dwelling MOB represent a potentially significant methane sink, and an important frontier for further research. The photosynthesis performed by trees makes them an important sink for atmospheric carbon dioxide, but trees are also sources of the potent greenhouse gas methane. Here the authors find that tree bark in some common lowland species is colonized by methane oxidizing bacteria that can reduce tree methane emissions by ~ 36%.