Chemostat culture of Bacillus caldotenax at 65°C: Activity and regulation of the main metabolic pathways |
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Authors: | U Friederich H J Kuhn H M Fischer A Fiechter |
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Institution: | (1) Swiss Federal Institute of Technology, CH-8092 Zürich |
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Abstract: | Bacillus caldotenax was cultivated in chemostat experiments at 65°C with a chemically defined minimal medium. Glycolysis, tricarboxylic acid cycle, pentose phosphate pathway and the respiratory chain were active as demonstrated by measuring the corresponding enzymes. No enzyme activity of the Entner-Doudoroff pathway could be detected. The specific activities of the citrate cycle enzymes were up to 10 times higher as compared to the enzymes of glycolysis. At dilution rates between 0.3 and 2.2 h-1 none of the main metabolic pathways was regulated. In contrast the isocitrate lyase was regulated (drop of activity with increasing growth rates). As a result of a batch culture with glucose and acetate as carbon sources a regulation model was proposed: glucose, or a metabolite of glucose, represses the isocitrate lyase; in the absence of glucose acetate acts as an inducer.Abbreviations DCIP
dichlorphenol indophenol
- ED
Entner-Doudoroff pathway
- EMP
Emden-Meyerhof-Parnas pathway
- ICL
isocitrate lyase
- PP
pentose phosphate pathway
- TCC
tricarbonic acid cycle |
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Keywords: | Bacillus caldotenax Main metabolic Pathways Enzyme activities at different growth rates Isocitrate lyase Regulation |
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