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Choline and N,N-dimethylethanolamine as direct substrates for methanogens
Andrew J Watkins1, Erwan G Roussel, Gordon Webster
1School of Earth and Ocean Sciences, Cardiff University, Cardiff, United Kingdom.
Applied and Environmental Microbiology
|September 25, 2012
Summary
Certain Methanococcoides archaea can directly use choline for methane production, a process previously thought to require bacterial partners. This finding expands the known metabolic capabilities of methanogens, impacting understanding of anaerobic digestion and methane cycling.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Choline (N,N,N-trimethylethanolamine) is abundant in sediments and utilized by mixed prokaryote cultures for methane production.
- Pure cultures of methanogens were previously not known to directly metabolize choline.
Purpose of the Study:
- To investigate the direct utilization of choline for methanogenesis by isolated Methanococcoides strains.
- To identify metabolic intermediates and new growth substrates derived from choline metabolism.
Main Methods:
- Isolation of Methanococcoides strains from diverse marine sediments.
- Cultivation experiments to assess substrate utilization and methanogenesis.
- Use of 2-bromoethanesulfonate (BES) to inhibit methanogenesis.
- Diauxic growth studies with choline and trimethylamine.
Main Results:
- Five Methanococcoides strains directly utilized choline for methanogenesis, producing ethanolamine.
- Dimmethylethanolamine was identified as a new growth substrate, while monomethylethanolamine was not.
- 2-bromoethanesulfonate (BES) inhibited choline-dependent methane production.
- Diauxic growth observed when choline and trimethylamine were supplied, with trimethylamine utilized first.
Conclusions:
- Certain Methanococcoides strains can directly metabolize choline, expanding the known substrate range for methanogens.
- This direct utilization reduces reliance on bacterial syntrophs for substrate supply in anaerobic environments.
- The findings contribute to a better understanding of methane cycling and microbial metabolism in sediments.
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