Production of butanediol by anaerobic microbial fermentation

Abstract

The invention provides methods for producing 2,3-butanediol by anaerobic fermentation. According to particular methods of the invention, 2,3-butanediol is produced by anaerobic fermentation of substrates including carbohydrate and carbon monoxide.

1 . A method of producing butanediol by microbial fermentation, the method including:
 a. providing a substrate;   b. in a bioreactor containing a culture of one or more micro-organisms, anaerobically fermenting the substrate to produce butanediol.   
     
     
         2 . A method according to  claim 1 , wherein the substrate comprises CO. 
     
     
         3 . A method according to  claim 2 , wherein the butanediol is 2,3-butanediol. 
     
     
         4 . A method according to  claim 3 , wherein the substrate comprising CO is provided at a sufficient level, such that 2,3-butanediol is produced. 
     
     
         5 . A method according to  claim 3 , wherein the substrate comprising CO is provided such that a specific rate of CO uptake of at least 0.4 mmol CO/gram dry cells weight of bacteria/minute by the culture is maintained. 
     
     
         6 . A method according to  claim 5 , wherein the substrate is provided such that a specific uptake rate of at least 0.6 mmol CO/g/min is maintained. 
     
     
         7 . A method according to  claim 5 , wherein the substrate is provided such that a specific uptake rate of at least 0.8 mmol CO/g/min is maintained. 
     
     
         8 . A method according to  claim 5 , wherein the substrate is provided such that a specific uptake rate of at least 1.0 mmol CO/g/min is maintained. 
     
     
         9 . A method of producing 2,3-butanediol by microbial fermentation, the method including:
 a. providing a substrate;   b. in a bioreactor containing a culture of one or more micro-organisms, anaerobically fermenting the substrate, wherein one or more micro-organisms includes one or more 2,3-butanediol dehydrogenase genes;   c. upregulating the 2,3-butanediol dehydrogenase gene(s), such that 2,3-butanediol is produced by the micro-organism(s).   
     
     
         10 . A method according to  claim 9 , wherein the substrate comprises CO. 
     
     
         11 . A method according to  claim 10 , wherein the substrate comprising CO is provided at a sufficient level, such that 2,3-butanediol is produced. 
     
     
         12 . A method according to  claim 10 , wherein the substrate comprising CO is provided such that a specific rate of CO uptake of at least 0.4 mmol CO/gram dry cells weight of bacteria/minute by the culture is maintained. 
     
     
         13 . A method according to  claim 9 , wherein one or more micro-organism(s) is  Clostridium autoethanogenum.    
     
     
         14 . A method according to  claim 2 , wherein the substrate comprising CO is gaseous and comprises at least about 15% to about 100% CO by volume. 
     
     
         15 . A method according to  claim 2 , wherein the substrate comprising CO comprises gas obtained as by-product from an industrial process. 
     
     
         16 . A method according to  claim 15 , wherein the substrate comprising CO comprises gas obtained from a steel mill. 
     
     
         17 . A method according to  claim 1  wherein the butanediol is 2,3-butanediol and the culture includes a culture of  Clostridium autoethanogenum.    
     
     
         18 . A method according to  claim 17 , wherein the substrate comprises one or more carbohydrates. 
     
     
         19 . A method providing a substrate according to  claim 18 , wherein the method includes an additional step of providing a substrate comprising CO before, and/or at the same time, and/or after the step of providing a substrate comprising one or more carbohydrates. 
     
     
         20 . 2,3-Butanediol produced by the method of  claim 3 . 
     
     
         21 - 23 . (canceled)