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Research Article
Bark-dwelling methanotrophic bacteria decrease methane emissions from trees
Luke C Jeffrey
Southern Cross University
Corresponding Author
ORCiD: https://orcid.org/0000-0001-6536-6757
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This work is licensed under a CC BY 4.0 License. Read Full License
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Tree stems are an important and unconstrained source of methane, yet it is uncertain if there are internal microbial controls (i.e. methanotrophy) within tree bark, that may reduce methane emissions. Using multiple lines of evidence, we demonstrate here that unique microbial communities dominated by methane oxidising bacteria (MOB) dwell within bark of Melaleuca quinquenervia, a common, invasive and globally distributed lowland species. Laboratory incubations of methane inoculated M. quinquenervia bark reveal methane consumption (up to 96.3 µmol m-2 bark d-1) and distinct isotopic δ13C-CH4 enrichment characteristic of MOB. Molecular analysis indicates unique microbial communities reside within the bark, with methane-oxidising bacteria primarily from the genus Methylomonas comprising up to 25 % of the total microbial community. Methanotroph abundance was linearly correlated to methane uptake rates (R2 = 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 novel and potentially significant methane sink, and an important frontier for further research.
Keywords
Tree stem methane, MOB, methanotroph, carbon cycle, lowland forests, wetlands, greenhouse gases, microbe, methanogen, isotope, Methylomonas, methane emissions
Figure 1
Figure 2
Figure 3
This is a list of supplementary files associated with this preprint. Click to download.
- FigureS1.png
Figure S1. Results of DFM experiments showing: (a) initial CH4 flux rates from M. quinquenervia stem; (b) % change in CH4 emissions ~1 hour after the addition of DFM to the stem chamber; (c) initial CH4 flux rates from M. quinquenervia stem for blank treatments; and (d) % change in CH4 emissions ~1 hour blank chamber measurements. Paired data ranked according to % change in CH4 emissions.
- FigureS2.png
Figure S2. (a) Relative abundance of 16S rRNA gene amplicon sequences resolved at the taxonomic level of phylum. (b) Non-metric multidimensional scaling (nMDS) ordination of the MOB community structure (beta diversity) measured by Bray-Curtis distance matrix of the 16S rRNA gene amplicon sequences.
- FigureS3.png
Figure S3. (a) Relative abundance of methanotrophic (MOB) community genera and uncultivated environmental clusters detected from the analysis of the pmoA gene amplicon sequences. (b) Non-metric multidimensional scaling (nMDS) ordination of the MOB community structure (beta diversity) measured by Bray-Curtis distance matrix of the pmoA gene amplicon sequences. (c), (d) Relative abundance of the Methylomonas amplicon sequence variants identified from the analysis of the 16S rRNA gene (c) and pmoA (d) amplicon sequences.
- SupplementaryTables.docx
Supplementary Tables
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This is a preprint. It has not completed peer review.
Research Article
Bark-dwelling methanotrophic bacteria decrease methane emissions from trees
Luke C Jeffrey
Southern Cross University
Corresponding Author
ORCiD: https://orcid.org/0000-0001-6536-6757
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 03 Dec, 2020
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Declarations:
Declarations
- The author has confirmed that a statement listing potential conflicts of interest or lack thereof is included in the text.
Tree stems are an important and unconstrained source of methane, yet it is uncertain if there are internal microbial controls (i.e. methanotrophy) within tree bark, that may reduce methane emissions. Using multiple lines of evidence, we demonstrate here that unique microbial communities dominated by methane oxidising bacteria (MOB) dwell within bark of Melaleuca quinquenervia, a common, invasive and globally distributed lowland species. Laboratory incubations of methane inoculated M. quinquenervia bark reveal methane consumption (up to 96.3 µmol m-2 bark d-1) and distinct isotopic δ13C-CH4 enrichment characteristic of MOB. Molecular analysis indicates unique microbial communities reside within the bark, with methane-oxidising bacteria primarily from the genus Methylomonas comprising up to 25 % of the total microbial community. Methanotroph abundance was linearly correlated to methane uptake rates (R2 = 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 novel and potentially significant methane sink, and an important frontier for further research.
Figure 1
Figure 2
Figure 3