Mutant
The invention relates to a mutant strain of bacteria, which either lacks or contains mutant genes for several key metabolic enzymes, and which produces high amounts of succinic acid under anaerobic conditions.
1. A genetically engineered bacterial strain wherein said bacteria comprise:
a) a disruption of ldhA;
b) a disruption of adhE; and
c) a disruption of ack-pta.
2. The bacterial strain of claim 1 , wherein said bacterial strain comprises a disruption of iclR.
3. The bacterial strain of claim 1 , wherein said bacterial strain comprises a pyc gene operably linked to an expression construct.
4. The bacterial strain of claim 1 , wherein said pyc is from Lactobacillus lactis.
5. The bacterial strain of claim 1 , wherein said bacterial strain comprises a citZ gene operably linked to an expression construct.
6. The bacterial strain of claim 5 , wherein said citZ is from Bacillus subtilis.
7. A method of producing succinic acid comprising:
a) culturing a bacterial strain of claim 1 under anaerobic conditions;
b) providing a sugar substrate;
c) allowing said bacteria to metabolize said substrate; and
d) isolating succinic acid.
8. The bacteria of claim 1 , wherein said bacterial strain produces greater than 1.5 moles of succinic acid per mole of glucose.
9. The method of claim 7 , wherein said bacterial strain produces greater than 1.5 moles of succinic acid per mole of glucose.