| 摘要 |
This invention relates to the biocatalysts for the efficient production of succinic acid and/or other products from renewable biological feedstocks. The biocatalysts have a very high efficiency for the growth-coupled production of succinic acid and/or other products from carbohydrate feed stocks as a result of both genetic manipulations and metabolic evolution. More specifically, certain biocatalysts of the present invention produce succinic acid at high titers and yield in mineral salts media during simple pH-controlled, batch fermentation without the addition of any exogenous genetic material. The genetic manipulations of the present invention are concerned with the energy-conserving strategies coupled with the elimination of alternative routes for NADH oxidation other than the routes for succinic acid production. The biocatalysts contain glucose-repressed gluconeogenic phosphoenol pyruvate carboxykinase (pck) depressed by genetic modifications and a genetically-inactivated phosphotransferase system. In terms of succinic acid production efficiency, the biocatalysts of the present invention are functionally equivalent to succinate producing rumen bacteria such as Actinobacillus succinogens and Mannheimia succiniproducens with one difference that the biocatalysts are able to achieve this high level of succinic acid production in a minimal salt medium with carbohydrate source as opposed to the requirement for a rich media for succinic acid production by rumen bacteria. |
