Method for Producing Butanol Using Extractive Fermentation

Abstract

The invention relates to a method for producing butanol through microbial fermentation, in which the butanol product is removed by extraction into a water immiscible organic extractant during the fermentation. The invention also relates to a method for producing butanol through microbial fermentation, in which the butanol product is removed during the fermentation by extraction into a water-immiscible extractant composition. The invention further relates to compositions comprising a solution of butanol in a water immiscible organic extractant composition.

1 . A method for recovering butanol from a fermentation medium, the method comprising:
 (a) providing a fermentation medium comprising butanol, water, and a recombinant microorganism comprising a butanol biosynthetic pathway, wherein the recombinant microorganism produces butanol;   (b) contacting the fermentation medium with a water immiscible organic extractant composition comprising a solvent selected from the group consisting of C 12  to C 22  fatty alcohols, C 12  to C 22  ethers, esters of C 12  to C 22  fatty acids, C 10  to C 22  alkanes, and mixtures thereof, to form a butanol-containing organic phase and an aqueous phase,
 wherein the solvent is biocompatible with the microorganism such that at least about 90% of the microorganisms are viable after exposure to the organic extractant composition, and wherein the solvent has a boiling point less than about 300° C., with the proviso that the organic extractant is not oleyl alcohol, 1-dodecanol, behenyl alcohol, cetyl alcohol, myristyl alcohol, or stearyl alcohol; and 
   (c) recovering the butanol from the butanol-containing organic phase.   
     
     
         2 . The method of  claim 1 , wherein the solvent is trimethylnonanol, methyl laurate, di-n-octyl ether, dodecane, n-undecane, ethyl decanoate, ethyl laurate, or mixtures thereof. 
     
     
         3 . A method for recovering butanol from a fermentation medium, the method comprising:
 a) providing a fermentation medium comprising butanol, water, and a recombinant microorganism comprising a butanol biosynthetic pathway, wherein the recombinant microorganism produces butanol;   b) contacting the fermentation medium with a water immiscible organic extractant composition comprising a solvent is trimethylnonanol, methyl laurate, di-n-octyl ether, dodecane, n-undecane, ethyl decanoate, ethyl laurate, or mixtures thereof, to form a butanol-containing organic phase and an aqueous phase; and   c) recovering the butanol from the butanol-containing organic phase.   
     
     
         4 . The method of  claim 1 , wherein the contacting of the organic extractant composition with the fermentation medium occurs in a fermentor. 
     
     
         5 . The method of  claim 1 , further comprising: transferring a portion of the fermentation medium from the fermentor to a vessel, wherein the contacting of the organic extractant composition with the fermentation medium occurs in the vessel. 
     
     
         6 . The method of  claim 1 , wherein the butanol is isobutanol. 
     
     
         7 . The method of  claim 1 , wherein the organic extractant composition further comprises an additional solvent, wherein the additional solvent is n-hexanol, methyl isobutyl carbinol, 2-ethyl-1-hexanol, 2,6-dimethylheptan-4-ol, or mixtures thereof. 
     
     
         8 . The method of  claim 7 , wherein the additional solvent is 2,6-dimethylheptan-4-ol. 
     
     
         9 . The method of  claim 1 , wherein the organic extractant composition further comprises an additional solvent with a butanol partition coefficient greater than about 4. 
     
     
         10 . The method of  claim 1 , wherein the organic extractant composition further comprises an additional solvent with a butanol partition coefficient greater than about 5. 
     
     
         11 . The method of  claim 1 , the organic extractant composition further comprises an additional solvent with a butanol partition coefficient greater than about 6. 
     
     
         12 . The method of  claim 1 , wherein the organic extractant composition further comprises an additional solvent with a butanol partition coefficient greater than about 7. 
     
     
         13 . The method according to  claim 9 , wherein the organic extractant composition further comprises an additional solvent, wherein the additional solvent is n-hexanol, methyl isobutyl carbinol, 2-ethyl-1-hexanol, 2,6-dimethylheptan-4-ol, or mixtures thereof. 
     
     
         14 . The method of  claim 13 , wherein the additional solvent is 2,6-dimethylheptan-4-ol. 
     
     
         15 . The method of  claim 1 , wherein the contacting comprises contacting the fermentation medium via a co-current or counter-current stream of the organic extractant composition. 
     
     
         16 . The method of  claim 1 , wherein the recovered butanol has an effective titer from about 22 g per liter to about 40 g per liter of the fermentation medium. 
     
     
         17 . The method of  claim 1 , wherein the recovered butanol has an effective titer of at least about 37 g per liter of the fermentation medium. 
     
     
         18 . A composition comprising a solution of butanol in a water immiscible organic extractant composition, wherein the organic extractant composition comprises a solvent selected from the group consisting of C 12  to C 22  fatty alcohols, C 12  to C 22  ethers, esters of C 12  to C 22  fatty acids, C 10  to C 22  alkanes, and mixtures thereof,
 wherein the solvent is biocompatible with a recombinant microorganism comprising a butanol biosynthetic pathway, wherein at least 90% of the recombinant microorganisms are viable after exposure to the organic extractant composition, and wherein the solvent has a boiling point less than about 300° C.,   with the proviso that the solvent is not oleyl alcohol, 1-dodecanol, behenyl alcohol, cetyl alcohol, myristyl alcohol, or stearyl alcohol.   
     
     
         19 . The composition of  claim 18 , wherein the solvent is trimethylnonanol, methyl laurate, di-n-octyl ether, dodecane, n-undecane, ethyl decanoate, ethyl laurate, or mixtures thereof. 
     
     
         20 . A composition comprising a solution of butanol in a water immiscible organic extractant composition comprising a solvent, wherein the solvent is trimethylnonanol, methyl laurate, di-n-octyl ether, dodecane, n-undecane, ethyl decanoate, ethyl laurate, or mixtures thereof. 
     
     
         21 . The composition of  claim 18 , wherein the organic extractant composition further comprises an additional solvent, wherein the additional solvent is n-hexanol, methyl isobutyl carbinol, 2-ethyl-1-hexanol, 2,6-dimethylheptan-4-ol, or mixtures thereof. 
     
     
         22 . The composition of  claim 21 , wherein the additional solvent is 2,6-dimethylheptan-4-ol. 
     
     
         23 . The composition of  claim 18 , wherein the butanol is isobutanol.