Sulfur and methane oxidation by a single microorganism

Area of Science:

• Microbiology
• Environmental Science
• Biogeochemistry

Background:

• Wetlands are significant sources of methane, a potent greenhouse gas.
• Methanotrophic bacteria mitigate methane emissions at oxic-anoxic interfaces.
• These interfaces involve complex redox cycling of carbon, sulfur, and nitrogen.

Purpose of the Study:

• To isolate and characterize novel methanotrophic bacteria from wetland environments.
• To investigate unique metabolic capabilities of isolated strains.
• To understand the interplay between methane and sulfur cycling.

Main Methods:

• Isolation and cultivation of aerobic methanotrophic bacteria.
• Genomic and proteomic analyses for metabolic pathway identification.
• Microrespirometry to assess substrate oxidation rates.

Main Results:

• Isolation of 'Methylovirgula thiovorans' strain HY1, a novel aerobic methanotroph.
• Strain HY1 uniquely oxidizes both methane and reduced sulfur compounds for growth.
• Genomic data revealed soluble methane monooxygenase, XoxF-type dehydrogenases, and sulfur oxidation pathways (Sox-rDsr, S4I).
• Calvin-Benson-Bassham cycle used for CO2 fixation during chemolithoautotrophic growth.
• Metabolic pathways for methane and thiosulfate oxidation are inducible and can occur simultaneously.

Conclusions:

• Methanotrophy and thiotrophy are compatible within a single microorganism.
• This discovery reveals a versatile bacterium with significant implications for understanding wetland biogeochemistry.
• Highlights the intricate interactions between methane and sulfur cycles at oxic-anoxic interfaces.