Environmental and physiological factors affecting the succinate product ratio during carbohydrate fermentation by Actinobacillus sp. 130Z |
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Authors: | M J Van der Werf Michael V Guettler Mahendra K Jain J Gregory Zeikus |
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Institution: | (1) Department of Biochemistry, Michigan State University, East Lansing, MI 48 824, USA, US;(2) MBI International, 3900 Collins Road, P.O. Box 27 609, Lansing, MI 48 909-0609, USA Tel. +1-517-337-3181; Fax +1-517-337-2122 e-mail: zeikus@mbi.org., US;(3) Department of Animal Science, Michigan State University, East Lansing, MI 48 824, USA, US |
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Abstract: | Actinobacillus sp. 130Z fermented glucose to the major products succinate, acetate, and formate. Ethanol was formed as a minor fermentation
product. Under CO2-limiting conditions, less succinate and more ethanol were formed. The fermentation product ratio remained constant at pH
values from 6.0 to 7.4. More succinate was produced when hydrogen was present in the gas phase. Actinobacillus sp. 130Z grew at the expense of fumarate and l-malate reduction, with hydrogen as an electron donor. Other substrates such as more-reduced carbohydrates (e.g., d-sorbitol) resulted in higher succinate and/or ethanol production. Actinobacillus sp. 130Z contained the key enzymes involved in the Embden-Meyerhof-Parnas and the pentose-phosphate pathways and contained
high levels of phosphoenolpyruvate (PEP) carboxykinase, malate dehydrogenase, fumarase, fumarate reductase, pyruvate kinase,
pyruvate formate-lyase, phosphotransacetylase, acetate kinase, malic enzyme, and oxaloacetate decarboxylase. The levels of
PEP carboxykinase, malate dehydrogenase, and fumarase were significantly higher in Actinobacillus sp. 130Z than in Escherichia coli K-12 and accounted for the differences in succinate production. Key enzymes in end product formation in Actinobacillus sp. 130Z were regulated by the energy substrates.
Received: 2 September 1996 / Accepted: 10 January 1997 |
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Keywords: | Phosphoenolpyruvate Metabolic fluxes Fermentation Carbon dioxide fixation Fumarate reduction Succinate Actinobacillus sp 130Z Escherichia coli |
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