Document Detail


Proton motive force, energy recycling by end product excretion, and metabolic uncoupling during anaerobic growth of Pseudomonas mendocina.
MedLine Citation:
PMID:  2254245     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Batch cultures of Pseudomonas mendocina, grown in rich medium with glucose excess, showed metabolic differences dependent upon whether the growth conditions were aerobic or anaerobic, with or without added electron acceptor. Under anaerobic conditions in the absence of nitrate, P. mendocina reached the stationary phase of growth after 2 or 3 days, followed by a stationary phase of 4 to 5 days. Under these conditions, a mixed-type fermentative metabolism (formic, lactic, and acetic acids) appeared. A fivefold-higher specific rate of glucose consumption and eightfold-higher production of organic acids, compared with aerobic cultures, were shown by this microorganism growing anaerobically in the absence of exogenous electron acceptors. The gradients of organic acid produced by P. mendocina under these conditions reached a maximum (lactate, 180 mV; formate, 150 mV; acetate, 215 mV) between days 2 and 3 of culture. The proton motive force (delta p) decreased during growth from -254 to -71 mV. The intracellular pH remained alkaline during the culture, reaching a steady-state value of 7.9. The gradients of organic acids apparently contributed to the generation of a delta p, which, according to the Energy Recycling Model (P. A. M. Michels, J. P. J. Michels, J. Boonstra, and W. N. Konings, FEMS Microbiol. Lett. 5:357-364, 1979), would produce an average energy gain of 1 or 1.5 mol of ATP equivalents per mol of glucose consumed with H+/ATP stoichiometry of 3 or 2, respectively. Low YATP and Yglucose values were observed, suggesting that an uncoupled metabolism exists; i.e., ATP produced by catabolic processes is not directly used for biomass synthesis. This metabolic uncoupling could be induced at least in part by organic acids and the ATP wastage could be induced by a membrane-bound ATPase involved in intracellular pH regulation.
Authors:
N Verdoni; M A Aon; J M Lebeault; D Thomas
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of bacteriology     Volume:  172     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  1990 Dec 
Date Detail:
Created Date:  1991-01-24     Completed Date:  1991-01-24     Revised Date:  2010-09-10    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  6673-81     Citation Subset:  IM    
Affiliation:
Division des Procedés Biotechnologiques, Université de Technologie de Compiègne.
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MeSH Terms
Descriptor/Qualifier:
Acids / metabolism
Aerobiosis
Anaerobiosis
Electron Transport
Energy Metabolism
Fermentation
Hydrogen-Ion Concentration*
Membrane Potentials
Pseudomonas / growth & development,  metabolism,  physiology*
Uncoupling Agents
Chemical
Reg. No./Substance:
0/Acids; 0/Uncoupling Agents
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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