title: Characterization of E. coli MG1655 and frdA and sdhC mutants at various aerobiosis levels.
abstract: Depending on the availability of oxygen, Escherichia coli is able to switch between aerobic respiratory metabolism and anaerobic mixed acid fermentation. An important, yet understudied, metabolic mode is the micro-aerobic metabolism at intermediate oxygen availabilities. The relationship between oxygen input, physiology and gene expression of E. coli MG1655 and two isogenic mutants lacking succinate dehydrogenase (SDH) and fumarate reductase (FRD) activities was analyzed at different aerobiosis levels. Growth rate and cell yield were very similar to the parent strain. By-product formation was altered in the sdhC mutant to higher acetic acid and glutamate production in batch cultures. In continuous cultures with defined oxygen input gene expression analysis revealed a dependency of many catabolic genes to aerobiosis. Acetate excretion was still detectable under aerobic conditions in the sdhC mutant; the frdA mutant lacked anaerobic succinate excretion. Anaerobic repression of the sdh operon was diminished in the frdA strain, possibly to allow SDH to partially replace FRD. The experiments illustrate the remarkable adaptability of E. coli physiology-to compensate for the absence of important metabolic genes by altering carbon flux and/or gene expression such that there are only minor changes in growth capability across the aerobiosis range.
authors: MPI für Dynamik Komplexer Technischer Systeme, Germany. steinsiek@mpi-magdeburg.mpg.de
authors: S
authors: S
authors: Steinsiek
authors: S
authors: S
authors: Frixel
authors: S
authors: S
authors: Stagge
authors: K
authors: K
authors: Bettenbrock
mesh_terms: D000085:Acetates / Q000378:metabolism; D000332:Aerobiosis / Q000187:drug effects / Q000235:genetics; D018533:Biomass; D002952:Citric Acid Cycle / Q000187:drug effects / Q000235:genetics; D004579:Electron Transport / Q000187:drug effects / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D009154:Mutation / Q000235:genetics*; D010100:Oxygen / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity / Q000187:drug effects; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism
chemical_list: D000085:Acetates; D029968:Escherichia coli Proteins; D012333:RNA, Messenger; D013385:Succinate Dehydrogenase; D010100:Oxygen