Recombinant microorganisms and methods of use thereof
Provided is a method of producing a product by culturing a carboxydotrophic acetogenic bacterium with a disrupting mutation in a lactate dehydrogenase enzyme in the presence of a substrate comprising CO, CO 2 , and/or H 2 . Preferably, the disrupting mutation reduces or eliminates the expression or activity of the enzyme such that the bacterium produces a reduced amount of lactate or no lactate.
1. A method of producing a product comprising culturing a carboxydotrophic acetogenic bacterium comprising a disrupting mutation in a lactate dehydrogenase enzyme in the presence of a substrate comprising CO, CO 2 , and/or H 2 whereby the bacterium produces a product selected from the group consisting of ethanol, 2,3-butanediol, formate, pyruvate, succinate, valine, leucine, isoleucine, malate, fumarate, 2-oxogluterate, citrate, and citramalate.
2. The method of claim 1 , wherein the disrupting mutation reduces or eliminates the expression or activity of the enzyme.
3. The method of claim 1 , wherein the disrupting mutation is a deletion of the lactate dehydrogenase enzyme or an inactivating mutation in the lactate dehydrogenase enzyme.
4. The method of claim 1 , wherein the bacterium produces a reduced amount of lactate compared to a parental bacterium.
5. The method of claim 1 , wherein the bacterium produces substantially no lactate.
6. The method of claim 1 , wherein the product is ethanol.
7. The method of claim 1 , wherein the bacterium produces an increased amount of the product compared to a parental bacterium.
8. The method of claim 7 , wherein the product is selected from ethanol, 2,3-butanediol, formate, pyruvate, succinate, valine, leucine, isoleucine, malate, fumarate, 2-oxogluterate, citrate, and citramalate.
9. The method of claim 8 , wherein the product is ethanol.
10. The method of claim 1 , wherein the bacterium comprises a Wood-Ljungdahl pathway.
11. The method of claim 1 , wherein the bacterium is derived from a parental bacterium selected from the group consisting of Clostridium autoethanogenum, Clostridium ljungdahlii , and Clostridium ragsdalei.