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Published on: September 14, 2013
Mesophilic cellulolytic clostridia from freshwater environments
S B Leschine1, E Canale-Parola
1Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003.
Applied and Environmental Microbiology
|September 1, 1983
Summary
New mesophilic, cellulolytic bacteria were discovered in freshwater mud. These anaerobic bacteria efficiently break down plant material, contributing to natural decomposition processes.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Cellulolytic bacteria play a crucial role in the anaerobic breakdown of plant polymers in aquatic environments.
- Understanding the diversity and function of these microorganisms is key to comprehending carbon cycling.
Purpose of the Study:
- To isolate and characterize novel obligately anaerobic, mesophilic, cellulolytic bacteria from freshwater environments.
- To compare the physiological and genetic characteristics of these isolates with known cellulolytic species.
Main Methods:
- Isolation of bacterial strains from freshwater mud samples.
- Morphological and Gram staining characterization.
- DNA guanine plus cytosine (GC) content determination.
- Fermentation studies of cellulose and other carbohydrates.
- Growth studies at different temperatures.
Main Results:
- Eight obligately anaerobic, mesophilic, cellulolytic bacterial strains (C strains) were isolated.
- Isolates were rod-shaped, Gram-negative, and formed terminal spores.
- DNA GC content ranged from 30.7 to 33.2 mol%.
- Fermentation of cellulose yielded acetate, ethanol, CO2, and H2, with reducing sugar accumulation.
- Strains exhibited unique characteristics, differing from Clostridium cellobioparum and Clostridium papyrosolvens.
- Unlike thermophilic species, these strains fermented xylan and pentoses (d-xylose, l-arabinose).
- Mesophilic strain C7 degraded cellulose at a rate comparable to Clostridium thermocellum at optimal temperatures.
Conclusions:
- The isolated C strains represent a novel group of mesophilic, cellulolytic bacteria.
- These bacteria contribute significantly to the anaerobic decomposition of plant polysaccharides in freshwater ecosystems.
- Their ability to degrade diverse plant polymers at mesophilic temperatures highlights their ecological importance.
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