Acid production by fermentation

Abstract

The invention provides methods for producing Lactate by anaerobic Fermentation. According to particular methods of the invention, Lactate is produced by anaerobic fermentation of a substrate comprising hydrogen and carbon monoxide.

1 - 21 . (canceled) 
     
     
         22 . A method of producing lactate by microbial fermentation, said method comprising:
 providing a substrate that includes CO;   in a bioreactor containing a culture of one or more micro-organisms, anaerobically fermenting the substrate to produce lactate.   
     
     
         23 . The method of  claim 22 , wherein providing the substrate comprises providing the substrate at a level sufficient to produce lactate. 
     
     
         24 . The method of  claim 22  wherein providing the substrate comprises providing the substrate at a level sufficient to maintain a specific CO uptake rate of at least 0.4 mmol CO/gram dry cells weight of bacteria/minute by the culture. 
     
     
         25 . The method of  claim 24 , wherein providing the substrate comprises providing the substrate at a level sufficient to maintain a specific CO uptake rate of at least 0.6 mmol CO/g/min. 
     
     
         26 . The method of  claim 22   wherein one or more of the one or more micro-organisms includes one or more lactate dehydrogenase genes, and   wherein the method further includes upregulating the lactate dehydrogenase gene(s), such that lactate is produced by the micro-organism(s).   
     
     
         27 . The method of  claim 26 , wherein providing the substrate comprises providing the substrate at a level sufficient to produce lactate. 
     
     
         28 . The method of  claim 26 , wherein providing a substrate that includes CO comprises providing the substrate at a level sufficient to maintain a specific rate of CO uptake of at least 0.4 mmol CO/gram dry cells weight of bacteria/minute by the culture. 
     
     
         29 . The method of  claim 22  wherein the one or more micro-organism(s) comprise  Clostridium autoethanogenum.    
     
     
         30 . The method of  claim 22  wherein providing a substrate that contains CO comprises providing a gaseous substrate. 
     
     
         31 . The method of  claim 30 , wherein providing a gaseous substrate comprises providing a gaseous substrate that contains at least about 15% to about 100% CO by volume. 
     
     
         32 . The method of  claim 30 , wherein providing a gaseous substrate that includes CO comprises providing gas obtained as a by-product from an industrial process. 
     
     
         33 . A method of producing lactate by microbial fermentation, the method including:
 providing a substrate   in a bioreactor that contains a culture having  Clostridium autoethanogenum , anaerobically fermenting the substrate to produce lactate.   
     
     
         34 . The method of  claim 33 , wherein providing a substrate comprises providing a substrate that includes one or more carbohydrates. 
     
     
         35 . The method of  claim 34 , wherein the method further comprises providing a substrate that includes CO before, at the same time, or after the step of providing a substrate comprising one or more carbohydrates. 
     
     
         36 . The method of  claim 35 , wherein the method further comprises alternating between providing a substrate comprising CO and providing a substrate comprising one or more carbohydrates.