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Requirement for a Microbial Consortium To Completely Oxidize Glucose in Fe(III)-Reducing Sediments
1Water Resources Division, U.S. Geological Survey, 430 National Center, Reston, Virginia 22092.
Applied and Environmental Microbiology
|December 1, 1989
Summary
In iron(III)-reducing sediments, [C]glucose fermentation produces fatty acids, similar to methanogenic environments. This suggests a combined bacterial action oxidizes substrates to carbon dioxide.
Area of Science:
- Environmental microbiology
- Geochemistry
- Biogeochemical cycles
Background:
- Iron(III) reduction is a key terminal electron-accepting process in anoxic sediments.
- Fermentation of organic matter is a crucial step in anaerobic decomposition.
- Understanding microbial metabolism in diverse sediment types is vital for biogeochemical studies.
Purpose of the Study:
- To investigate the fate of fermentable substrates in iron(III)-reducing sediments.
- To compare glucose fermentation pathways in iron(III)-reducing versus methanogenic sediments.
- To elucidate the microbial consortia involved in substrate oxidation in iron(III)-reducing environments.
Main Methods:
- Incubation of sediments under conditions where iron(III) reduction is the terminal electron-accepting process.
- Tracer studies using [C]glucose to track metabolic pathways.
- Analysis of fermentation products, specifically carbon fatty acids.
Main Results:
- Fermentation of [C]glucose to carbon fatty acids was observed in iron(III)-reducing sediments.
- The observed fermentation pattern closely resembled that found in methanogenic sediments.
- These findings support the role of fermentative bacteria and fatty acid-oxidizing, iron(III)-reducing bacteria.
Conclusions:
- Fermentable substrates are oxidized to carbon dioxide in iron(III)-reducing sediments.
- This oxidation is mediated by a synergistic activity of fermentative bacteria and specialized iron(III)-reducing bacteria.
- The microbial ecology of iron(III)-reducing sediments shares functional similarities with methanogenic environments regarding substrate utilization.
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