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Title: Comparison of unitrophic and mixotrophic substrate metabolism by an acetate-adapted strain of Methanosarcina barkeri

Abstract

We examined the unitrophic metabolism of acetate and methanol individually and the mixotrophic utilization of these compounds by using detailed /sup 14/C-labeled tracer studies in a strain of Methanosarcina barkeri adapted to grow on acetate as the sole carbon and energy source. The substrate consumption rate and methane production rate were significantly lower on acetate alone than during the unitrophic or mixotrophic metabolism of methanol. Cell yields (in grams per mole of substrate) were identical during exponential growth on acetate and exponential growth on methanol. During unitrophic metabolism of acetate, the methyl moiety accounted for the majority of the CH/sub 4/ produced, but 14% of the CO/sub 2/ generated originated from the methyl moiety. This correlated with the concurrent reduction of equivalent amounts of the C-1 of acetate to CH/sub 4/. /sup 14/CH/sub 4/ was also produced from added /sup 14/CO/sub 2/, although to a lesser extent than from reduction of the C-1 of acetate. During mixotrophic metabolism, methanol and acetate were catabolized simultaneously. The rates of /sup 14/CH/sub 4/ and /sup 14/CO/sub 2/ generation from (2-/sup 14/C)acetate were logarithmic and higher in mixotrophic than in unitrophic cultures at substrate concentrations of 50 mM. A comparison of the oxidoreductase activitiesmore » in cell extracts of the acetate-adapted strain grown on acetate and of strain MS grown on methanol or on H/sub 2/ plus CO/sub 2/ indicated that the pyruvate, ..cap alpha..-ketoglutarate, and isocitrate dehydrogenase activities remained constant, whereas the CO dehydrogenase activity was significantly higher (5,000 nmol/min per mg of protein) in the acetate-adapted strain. These results suggested that a significant intramolecular redox pathway is possible for the generation of CH/sub 4/ from acetate, that energy metabolism from acetate by M. barkeri is not catabolite repressed by methanol, and that the acetate-adapted strain is a metabolic mutant with depressed CO dehydrogenase activity.« less

Authors:
; ;
Publication Date:
Research Org.:
University of Wisconsin, Madison
OSTI Identifier:
5732116
Resource Type:
Journal Article
Journal Name:
J. Bacteriol.; (United States)
Additional Journal Information:
Journal Volume: 149:1
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ACETATES; METABOLISM; CARBON 14 COMPOUNDS; UPTAKE; METHANE; PRODUCTION; METHANOGENIC BACTERIA; COMPARATIVE EVALUATIONS; PRODUCTIVITY; METHANOL; BIOLOGICAL PATHWAYS; CARBON DIOXIDE; CATABOLISM; ENZYME ACTIVITY; EXPERIMENTAL DATA; GROWTH; MUTANTS; OXIDOREDUCTASES; REDOX REACTIONS; SUBSTRATES; TRACER TECHNIQUES; ALCOHOLS; ALKANES; BACTERIA; CARBON COMPOUNDS; CARBON OXIDES; CARBOXYLIC ACID SALTS; CHALCOGENIDES; CHEMICAL REACTIONS; DATA; ENZYMES; HYDROCARBONS; HYDROXY COMPOUNDS; INFORMATION; ISOTOPE APPLICATIONS; LABELLED COMPOUNDS; MICROORGANISMS; NUMERICAL DATA; ORGANIC COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; 550700* - Microbiology; 550500 - Metabolism

Citation Formats

Krzycki, J A, Wolkin, R H, and Zeikus, J G. Comparison of unitrophic and mixotrophic substrate metabolism by an acetate-adapted strain of Methanosarcina barkeri. United States: N. p., 1982. Web.
Krzycki, J A, Wolkin, R H, & Zeikus, J G. Comparison of unitrophic and mixotrophic substrate metabolism by an acetate-adapted strain of Methanosarcina barkeri. United States.
Krzycki, J A, Wolkin, R H, and Zeikus, J G. Fri . "Comparison of unitrophic and mixotrophic substrate metabolism by an acetate-adapted strain of Methanosarcina barkeri". United States.
@article{osti_5732116,
title = {Comparison of unitrophic and mixotrophic substrate metabolism by an acetate-adapted strain of Methanosarcina barkeri},
author = {Krzycki, J A and Wolkin, R H and Zeikus, J G},
abstractNote = {We examined the unitrophic metabolism of acetate and methanol individually and the mixotrophic utilization of these compounds by using detailed /sup 14/C-labeled tracer studies in a strain of Methanosarcina barkeri adapted to grow on acetate as the sole carbon and energy source. The substrate consumption rate and methane production rate were significantly lower on acetate alone than during the unitrophic or mixotrophic metabolism of methanol. Cell yields (in grams per mole of substrate) were identical during exponential growth on acetate and exponential growth on methanol. During unitrophic metabolism of acetate, the methyl moiety accounted for the majority of the CH/sub 4/ produced, but 14% of the CO/sub 2/ generated originated from the methyl moiety. This correlated with the concurrent reduction of equivalent amounts of the C-1 of acetate to CH/sub 4/. /sup 14/CH/sub 4/ was also produced from added /sup 14/CO/sub 2/, although to a lesser extent than from reduction of the C-1 of acetate. During mixotrophic metabolism, methanol and acetate were catabolized simultaneously. The rates of /sup 14/CH/sub 4/ and /sup 14/CO/sub 2/ generation from (2-/sup 14/C)acetate were logarithmic and higher in mixotrophic than in unitrophic cultures at substrate concentrations of 50 mM. A comparison of the oxidoreductase activities in cell extracts of the acetate-adapted strain grown on acetate and of strain MS grown on methanol or on H/sub 2/ plus CO/sub 2/ indicated that the pyruvate, ..cap alpha..-ketoglutarate, and isocitrate dehydrogenase activities remained constant, whereas the CO dehydrogenase activity was significantly higher (5,000 nmol/min per mg of protein) in the acetate-adapted strain. These results suggested that a significant intramolecular redox pathway is possible for the generation of CH/sub 4/ from acetate, that energy metabolism from acetate by M. barkeri is not catabolite repressed by methanol, and that the acetate-adapted strain is a metabolic mutant with depressed CO dehydrogenase activity.},
doi = {},
journal = {J. Bacteriol.; (United States)},
number = ,
volume = 149:1,
place = {United States},
year = {1982},
month = {1}
}