Involvement of d-lactate and lactic acid racemase in the metabolism of glucose by Selenomonas ruminantium |
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Authors: | Stephen B Melville Tomas A Michel Joan M Macy |
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Institution: | Department of Animal Science, University of California, Davis, CA, U.S.A. |
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Abstract: | Selenomonas ruminantium HD4 produced significant quantities of d- and l-lactate from glucose in batch culture. Both isomers also supported growth if fumarate was present. In glucose-limited continuous culture, d-lactate was detected in the medium only at fast dilution rates. In continuous-culture-grown cells, only a cytoplasmic NAD-dependent l-lactate dehydrogenase (LDH) and a membrane-associated NAD-independent l-LDH were detected; activity of the soluble enzyme was twice as high at the fast dilution rate as at the slow dilution rate. Lactate racemase was also detected; its activity was 4-fold higher at the fast dilution rate. The presence of racemase explains why d-lactate was made and used by this organism. |
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Keywords: | Selenomonas ruminantium Lactate racemase d-Lactate Glucose (Glucose metabolism) |
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