Pathway of propionate formation in Desulfobulbus propionicus |
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Authors: | Alfons J M Stams Diderik R Kremer Klaas Nicolay Gerard H Weenk Theo A Hansen |
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Institution: | (1) Department of Microbiology, University of Groningen, Kerklaan 30, NL-9751 NN Haren, The Netherlands;(2) Department of Physical Chemistry, University of Groningen, Niienborgh 16, NL-9747 AG Groningen, The Netherlands;(3) Present address: Department of Molecular Biology, University of Utrecht, Transitorium 3, Padualaan 8, NL-3508 TB Utrecht, The Netherlands |
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Abstract: | Whole cells of Desulfobulbus propionicus fermented 1-13C]ethanol to 2-13C] and 3-13C]propionate and 1-13C]-acetate, which indicates the involvement of a randomizing pathway in the formation of propionate. Cell-free extracts prepared from cells grown on lactate (without sulfate) contained high activities of methylmalonyl-CoA: pyruvate transacetylase, acetase kinase and reasonably high activities of NAD(P)-independent L(+)-lactate dehydrogenase NAD(P)-independent pyruvate dehydrogenase, phosphotransacetylase, acetate kinase and reasonably high activity of NAD(P)-independent L(+)-lactate dehydrogenase, fumarate reductase and succinate dehydrogenase. Cell-free extracts catalyzed the conversion of succinate to propionate in the presence of pyruvate, CoA and ATP and the oxaloacetate-dependent conversion of propionate to succinate. After growth on lactate or propionate in the presence of sulfate similar enzyme levels were found except for fumarate reductase which was considerably lower. Fermentative growth on lactate led to higher cytochrome b contents than growth with sulfate as electron acceptor.The labeling studies and the enzyme measurements demonstrate that in Desulfobulbus propionate is formed via a succinate pathway involving a transcarboxylase like in Propionibacterium. The same pathway may be used for the degradation of propionate to acetate in the presence of sulfate.Abbreviations DCPIP
2,6-dichlorophenolindophenol
- PEP
phosphoenolpyruvate |
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Keywords: | Propionate formation 13C NMR Desulfobulbus propionicus Sulfate reducing bacteria |
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