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Methylocella species are facultatively methanotrophic
Svetlana N Dedysh1, Claudia Knief, Peter F Dunfield
1S. N. Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow 117312, Russia.
Journal of Bacteriology
|June 22, 2005
Summary
Certain methanotrophic bacteria, like Methylocella, can grow on carbon compounds beyond just methane. This finding challenges previous understandings of methane-consuming bacteria and their environmental roles.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Aerobic methanotrophic bacteria traditionally utilize only one-carbon compounds for growth.
- This metabolic limitation has been a key factor in understanding methane cycling in ecosystems.
Purpose of the Study:
- To investigate the metabolic capabilities of the recently discovered genus Methylocella.
- To determine if Methylocella can grow on substrates containing carbon-carbon bonds, challenging the established understanding of methanotrophs.
Main Methods:
- Growth experiments using Methylocella silvestris BL2 with methane and acetate as sole carbon sources.
- Quantitative real-time PCR to monitor the methane monooxygenase (mmoX) gene expression.
- 16S rRNA gene cloning and fluorescence in situ hybridization to confirm culture purity.
Main Results:
- Methylocella demonstrated facultative growth on both one-carbon (methane) and multicarbon (acetate) compounds.
- mmoX gene copies increased with cell counts during growth on acetate, confirming the genetic basis for methane oxidation.
- Growth rate and carbon conversion were higher on acetate than methane, with acetate preferential utilization and methane oxidation shutdown when both were present.
Conclusions:
- Methanotrophic bacteria are not universally restricted to one-carbon substrates.
- The facultative growth of Methylocella expands the known metabolic diversity of methanotrophs.
- This finding has significant implications for models of environmental methane fluxes and microbial ecology.