Recombinant microorganisms and methods of use thereof

Abstract

The invention provides a carboxydotrophic acetogenic bacterium comprising a disrupting mutation in a lactate biosynthesis pathway enzyme and a method of producing a product by culturing the bacterium in the presence of a substrate comprising carbon monoxide. Preferably, the lactate biosynthesis pathway enzyme is lactate dehydrogenase (LDH) or another enzyme that converts pyruvate to lactate, wherein 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 carboxydotrophic acetogenic bacterium comprising a disrupting mutation in a lactate biosynthesis pathway enzyme. 
     
     
         2 . The bacterium of  claim 1 , wherein the mutation reduces or eliminates the expression or activity of the enzyme. 
     
     
         3 . The bacterium of  claim 1 , wherein the bacterium produces a reduced amount of lactate compared to a parental bacterium. 
     
     
         4 . The bacterium of  claim 1 , wherein the bacterium produces substantially no lactate. 
     
     
         5 . The bacterium of  claim 1 , wherein the bacterium produces one or more of ethanol, 2,3-butanediol, formate, pyruvate, succinate, valine, leucine, isoleucine, malate, fumarate, 2-oxogluterate, citrate, and citramalate. 
     
     
         6 . The bacterium of  claim 1 , wherein the bacterium produces an increased amount of one or more of ethanol, 2,3-butanediol, formate, pyruvate, succinate, valine, leucine, isoleucine, malate, fumarate, 2-oxogluterate, citrate, and citramalate compared to a parental bacterium. 
     
     
         7 . The bacterium of  claim 1 , wherein the enzyme natively converts pyruvate to lactate. 
     
     
         8 . The bacterium of  claim 1 , wherein the enzyme is lactate dehydrogenase (LDH). 
     
     
         9 . The bacterium 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.    
     
     
         10 . The bacterium of  claim 9 , wherein the parental bacterium is  Clostridium autoethanogenum  deposited under DSMZ accession number DSM23693. 
     
     
         11 . A method of producing a product comprising culturing the bacterium of  claim 1  in the presence of a substrate comprising CO whereby the bacterium produces a product. 
     
     
         12 . The method of  claim 11 , wherein the mutation reduces or eliminates the expression or activity of the enzyme. 
     
     
         13 . The method of  claim 11 , wherein the bacterium produces a reduced amount of lactate compared to a parental bacterium. 
     
     
         14 . The method of  claim 11 , wherein the bacterium produces substantially no lactate. 
     
     
         15 . The method of  claim 11 , wherein the product comprises one or more of ethanol, 2,3-butanediol, formate, pyruvate, succinate, valine, leucine, isoleucine, malate, fumarate, 2-oxogluterate, citrate, and citramalate. 
     
     
         16 . The method of  claim 11 , wherein the bacterium produces an increased amount of the product compared to a parental bacterium. 
     
     
         17 . The method of  claim 11 , wherein the enzyme natively converts pyruvate to lactate. 
     
     
         18 . The method of  claim 11 , wherein the enzyme is lactate dehydrogenase (LDH). 
     
     
         19 . The method of  claim 11 , wherein the bacterium is derived from a parental bacterium selected from the group consisting of  Clostridium autoethanogenum, Clostridium ljungdahlii , and  Clostridium ragsdalei.    
     
     
         20 . The method of  claim 19 , wherein the parental bacterium is  Clostridium autoethanogenum  deposited under DSMZ accession number DSM23693.