In vivo 13C NMR analysis of acetate metabolism in Thiobacillus versutus under denitrifying conditions |
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Authors: | P. A. M. Claassen C. Dijkema J. Visser A. J. B. Zehnder |
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Affiliation: | (1) Department of Microbiology, Agricultural University, NL-6703 CT Wageningen, The Netherlands;(2) Department of Molecular Physics, Agricultural University, NL-6703 CT Wageningen, The Netherlands;(3) Department of Genetics, Agricultural University, NL-6703 CT Wageningen, The Netherlands |
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Abstract: | The disappearance of 2-13C-acetate and the subsequent incorporation of label into cellular metabolites were followed in denitrifying cells of Thiobacillus versutus by 13C NMR spectroscopy. In cells grown under acetate-limitation, the specific rate of consumption was idependent of the density of the cell suspension. An isotopic steady state was reached within 30 min if sufficient substrate was added to the cell suspension. In cells grown under nitrate-limitation, the consumption of 2-13C-acetate proceeded at a significantly lower rate. The decrease and final disappearance of 2-13C-acetate were accompanied by incorporation of 13C into glutamate, glutamine, and by the release of labeled HCO3–and CO2. The appearance of a broad resonance being the methyl endgroup of poly-3-hydroxybutyrate (PHB) was indicative for PHB mobilization during the incubation. The sequence of label incorporation and the distribution among the various carbon nuclei were consistent with the operation of the tricarboxylic acid cycle. |
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Keywords: | Thiobacillus versutus TCA cycle 13C incorporation PHB metabolism |
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