Bark-dwelling methanotrophic bacteria decrease methane emissions from trees.

Area of Science:

• Microbial Ecology
• Biogeochemistry
• Environmental Science

Background:

• Tree stems are a significant source of methane, a potent greenhouse gas.
• The role of internal microbial communities, specifically methanotrophy in tree bark, in regulating methane emissions remains unclear.

Purpose of the Study:

• To investigate the presence and function of methane-oxidizing bacteria (MOB) within the bark of Melaleuca quinquenervia.
• To quantify the impact of bark-dwelling MOB on methane consumption and emission reduction.

Main Methods:

• Laboratory incubations of M. quinquenervia bark with methane.
• Isotopic analysis (δ13C-CH4) to confirm methanotrophy.
• Molecular analysis to identify microbial communities, focusing on MOB abundance.
• Field experiments to inhibit methane oxidation and measure emission changes.

Main Results:

• Unique microbial communities, dominated by MOB (genus Methylomonas), were identified in M. quinquenervia bark.
• Bark demonstrated significant methane consumption in laboratory settings (up to 96.3 µmol m-2 bark d-1).
• MOB abundance correlated positively with methane uptake rates (R2 = 0.76, p = 0.006).
• Field experiments showed bark-dwelling MOB reduce methane emissions by 36 ± 5%.

Conclusions:

• Bark of M. quinquenervia hosts a functional microbial community capable of methane oxidation.
• Bark-dwelling MOB represent a significant, previously underestimated methane sink.
• Further research into microbial methane cycling within tree bark is warranted.