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Acidophilic methanotrophic communities from Sphagnum peat bogs
S N Dedysh1, N S Panikov, J M Tiedje
1Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia.
Applied and Environmental Microbiology
|March 21, 1998
Summary
Researchers enriched acid-loving methane-consuming bacteria (methanotrophs) from boreal peat bogs. These moderate acidophiles thrive in acidic conditions, showing optimal growth and methane uptake between pH 4.5-5.5.
Area of Science:
- Microbiology
- Environmental Science
- Biogeochemistry
Background:
- Methane-consuming bacteria, or methanotrophs, play a crucial role in mitigating greenhouse gas emissions.
- Acidic peat bogs are significant methane sources, yet harbor unique microbial communities adapted to these environments.
- Understanding methanotrophic communities in acidic ecosystems is vital for predicting methane cycling and developing mitigation strategies.
Purpose of the Study:
- To enrich and characterize methanotrophic bacteria from acidic boreal forest peat bogs.
- To investigate the physiological and genetic properties of these acidophilic methanotrophs.
- To determine the optimal growth conditions for these communities, particularly pH and salt concentration.
Main Methods:
- Enrichment of methanotrophic communities using diluted mineral media with low buffering capacity at pH 3-6 and 20°C.
- Cultivation and isolation of bacterial strains, including Hyphomicrobium-like cells.
- Analysis of growth stoichiometry and methane (CH4) uptake rates.
- Polymerase chain reaction (PCR) amplification and sequencing of methane monooxygenase (mmoX) genes.
- Determination of pH optima for growth and methane consumption.
Main Results:
- Highly enriched methanotrophic communities were obtained after >25 serial transfers from four boreal peat bog sites.
- Enriched communities consisted primarily of rod-shaped bacteria in aggregates, with some Hyphomicrobium-like cells.
- Growth stoichiometry aligned with known methanotrophs, yielding 0.41 g biomass C/g CH4-C.
- PCR analysis confirmed the presence of mmoX and mmoY genes, with mmoX sequences showing affiliation to Methylocystis-Methylosinus and a distinct novel lineage.
- Optimal growth and methane uptake occurred at pH 4.5-5.5, indicating moderate acidophily, with enhanced growth in low-salt media.
Conclusions:
- The study successfully enriched moderate acidophilic methanotrophs from acidic boreal peat bogs.
- These methanotrophs exhibit distinct genetic profiles and physiological adaptations to acidic, low-salt environments.
- The findings provide insight into microbial methane cycling in peatlands and the specific adaptations of methanotrophs to acidic conditions.