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http://hdl.handle.net/2239/33349
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| Title: | Native and modified lactate dehydrogenase expression in a fumaric acid producing isolate Rhizopus oryzae 99-880. |
| Authors: | Skory, Christopher D.
Ibrahim, Ashraf S.
USDA, ARS |
| Keywords: | Lactic
Transformation
Orotate phosphoribosyltransferase
Fumaric
Rhizopus oryzae
Rhizopus arrhizus
lactate dehydrogenase |
| Issue Date: | 17-Oct-2007 |
| Description: | Rhizopus oryzae is subdivided into two groups based on genetic and phenotypic differences. Type-I isolates accumulate primarily lactic acid when grown in the presence of a fermentable carbon source and contain two lactate dehydrogenase genes, ldhA and ldhB. Type-II isolates synthesize predominantly fumaric acid and only have an ldhB gene. In this study, we determined that ldhB transcript is only minimally expressed in the Type-II isolate R. oryzae 99-880. LdhB enzyme purified from gene clones isolated from the Type-I isolate R. oryzae NRRL 395 and the Type-II isolate R. oryzae 99-880 each showed reductive LDH activity (pyruvate to lactate), while no oxidative LDH activity (lactate to pyruvate) was detected in either preparation. A transformation system was then developed for the first time with R. oryzae 99-880, using a uracil auxotrophic isolate that could be complemented with an orotate phosphoribosyltransferase gene, pyrF, isolated in this study. Transformation of this Type-II isolate with the ldhA gene from R. oryzae NRRL 395 resulted in reductive LDH activity between 1.0 and 1.8 U/mg total protein. Additionally, transformed isolates grown with glucose accumulated up to 27 g lactic acid/l with a concurrent decrease in fumaric acid, ethanol, and glycerol compared with the untransformed and vector-transformed control strains. |
| URI: | http://seekspace.resip.ac.cn/handle/2239/33349 |
| Other Identifiers: | http://seekspace.resip.ac.cn/handle/10113/2535 |
| Appears in Collections: | 网络开放学术资源
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