Microbial Ecology of Pectin Decomposition in Anoxic Lake Sediments
Bernhard Schink,J. G. Zeikus +1 more
TLDR
The numbers of pectinolytic anaerobes varied seasonally in both sediments, and were highest during the fall after sedimentation of algal blooms and/or leaf detritus, and the pH remaining neutral.Abstract:
SUMMARY: Anaerobic digestion of pectin by bacteria was examined in two freshwater lakes in Wisconsin and in defined laboratory cultures of species prevalent in the lake sediment. The turnover times for pectin biodegradation to methane in sediments incubated at in situ temperature were much longer (100 h in Lake Mendota and 185 h in Knaack Lake) than either that observed for glucose (12 h in Lake Mendota) or previously reported for acetate (0·22 h in Lake Mendota). The numbers of pectinolytic anaerobes varied seasonally in both sediments (102--105 and 103--105 ml-1 in Knaack Lake and Lake Mendota, respectively), and were highest during the fall after sedimentation of algal blooms and/or leaf detritus. Clostridium butyricum was identified as a prevalent pectinolytic anaerobe in both lakes. In mono-culture pectin fermentations, C. butyricum produced methanol, H2/CO2, acetate, ethanol and butyrate; growth stopped in the presence of excess energy source when the pH fell to 4·3. In co-culture pectin fermentations of C. butyricum/Methanosarcina barkeri, H2/CO2, methanol and acetate were detected as intermediary metabolites, and pectin was completely degraded to CH4 and CO2, the pH remaining neutral. 14C-radiotracer analysis substantiated the simultaneous conversion of H2/CO2, methanol and acetate to CH4 by M. barkeri as these metabolites were generated from pectin hydrolysis by C. butyricum.read more
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Comparison of microbial dynamics in marine and freshwater sediments: Contrasts in anaerobic carbon catabolism1
TL;DR: The microbiota of freshwater and marine sediments serve similar roles in carbon degradation and nutrient regeneration, however, because of differences in the chemical environment between freshwater and Marine systems, distinct physiological groups of bacteria dominate terminal carbon catabolism in each system.
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Quantification of methanogenic pathways using stable carbon isotopic signatures: a review and a proposal
TL;DR: In this article, the relative contribution of two methanogenic pathways to total CH4 production can be quantified when the stable carbon isotopic signatures of CO2, CH4 and acetate methyl are measured for the CH 4 production site and the isotopic fractionation factors are known for the conversion of CO 2 and of acetatemethyl to CH4.
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Biogeochemical cycling in an organic-rich coastal marine basin 4. An organic carbon budget for sediments dominated by sulfate reduction and methanogenesis
TL;DR: In situ carbon flux measurements and calculated burial rates are utilized to construct an organic carbon budget for the upper meter of sediment at a single station in Cape Lookout Bight, a small marine basin located on the Outer Banks of North Carolina, U.S.A as discussed by the authors.
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Glycerol conversion to 1,3-propanediol by newly isolated clostridia
TL;DR: The observations point to a substantial transfer of reducing potential from ferredoxin to NAD, which finally results in increased 1,3-propanediol production.
Journal ArticleDOI
Utilization of hydrogen, acetate, and “noncompetitive”; substrates by methanogenic bacteria in marine sediments
TL;DR: One hypothesis explaining the coexistence of sulfate reduction and methanogenesis in marine sediments is that methanogens use substrates for which competition is minimal or nonexistent.
References
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Book
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Journal ArticleDOI
Effect of sulfate on carbon and electron flow during microbial methanogenesis in freshwater sediments.
M R Winfrey,J G Zeikus +1 more
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J. G. Zeikus,R. S. Wolee +1 more
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TL;DR: The rate of sediment methanogenesis was shown to vary with respect to sediment site and depth, sampling date, in situ temperature, and number of methanogens, and correlated with increased sediment temperature during seasonal change.
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