Ecophysiology, inter-domain interactions, and biogeochemical impact of an aerobic methane-producing freshwater bacterium
EMSL Project ID
51544
Abstract
Methane is a potent greenhouse gas and understanding its sources and sinks is a core goal of the BER and DOE missions. Freshwater systems are responsible for approximately 16% of global methane emissions but significant gaps remain in understanding how this methane is generated in lakes and other environments. Biological methane production is traditionally viewed to be a strictly anaerobic process. However, in deep, thermally stratified freshwater lakes a well-defined pelagic methane enriched zone (2,000-3,000 % over-saturation) is observed in the presence of oxygen. This zone is manifested as a distinct section of the water column wherein microbial methane production proceeds under oxygen-saturated conditions devoid of archaeal methanogens and is not associated with deeper benthic activity. We have recently isolated an aerobic bacterium from Yellowstone Lake that encodes a single enzyme capable of releasing methane from methylamine under oxic conditions, providing a yet unaccounted-for source for methane in aerobic organisms. This discovery radically breaks from previous observations that identify methane as the final degradation product of anaerobic archaea and suggests that many more organisms and ecosystems might be involved in the production of this climate-active gas. Our proposed FICUS project has three main aims:
1. Determine the ecophysiology of Acidovorax sp. in Yellowstone lake and its contribution to CH4 production. This includes quantification of carbon and nitrogen uptake from MeA into Acidovorax under in situ-like conditions and the rate at which it is transcriptionally active in the lake.
2. Test our hypothesis that Acidovorax is metabolically coupled, and possibly physically associated, with lake algae, which produce metabolic precursors for CH4 production by Acidovorax.
3. Test our hypothesis that aerobic methanotrophs oxidize the Acidovorax-derived CH4 and methylotrophs, specifically members of the genus Methylopumilus, compete with Acidovorax for MeA in situ. Both processes would serve to constrain CH4 emissions from the lake surface.
Project Details
Project type
FICUS Research
Start Date
2020-10-01
End Date
2023-03-31
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)