Enzymatic production of alcohol esters for recovery of diols produced by fermentation

Abstract

Diols produced in fermentation are processed in broth by esterification of the product diol with a carboxylic acid (e.g., fatty acid) and a catalyst (e.g., lipase) capable of esterifying the product diol, such as 1,3-propanediol, with the carboxylic acid to form the diol esters. The diol esters can be extracted from the broth, and the product diol recovered from the diol esters. The carboxylic acid can also serve as an extractant for removal of the diol esters from the fermentation medium.

What is claimed is: 
     
         1 . A method for recovering a diol from a fermentation process comprising:
 a) providing a fermentation medium or fermentation product broth containing a diol;   b) contacting the diol in the fermentation medium or fermentation product broth with at least one carboxylic acid and at least one catalyst capable of esterifying the carboxylic acid with the diol to form diol esters of the carboxylic acid in the presence of an organic solvent which is present at a concentration sufficient to produce a two-phase mixture;   c) separating the diol ester-containing organic phase from the aqueous phase; and   d) hydrolyzing the diol ester into carboxylic acid and diol; and   e) recovering the diol.   
     
     
         2 . A method for producing a diol from a biomass feedstock comprising:
 a) providing a biomass feedstock;   b) liquefying the biomass feedstock to create a feedstock slurry comprising oligosaccharides;   c) saccharifying the oligosaccharides of the feedstock slurry to produce fermentable sugars;   d) fermenting the fermentable sugars using a microorganism to produce a diol in a fermentation medium or a fermentation product broth;   e) contacting the diol in the fermentation medium or fermentation product broth with at least one carboxylic acid and at least one catalyst capable of esterifying the carboxylic acid with the diol to form diol esters of the carboxylic acid in the presence of an organic solvent which is present at a concentration sufficient to produce a two-phase mixture;   f) separating the diol ester-containing organic phase from the aqueous phase;   g) hydrolyzing the diol ester into carboxylic acid and diol; and   h) recovering the diol.
 wherein optionally steps (c) and (d) occur concurrently, optionally steps (d) and (e) occur concurrently, or optionally steps (c), (d), and (e) occur concurrently. 
   
     
     
         3 . The method of  claim 1  or  2  wherein the organic solvent comprises said carboxylic acid and at least one non-reactive organic solvent. 
     
     
         4 . The method of  claim 3  wherein the non-reactive organic solvent is other than carboxylic acid or alcohol. 
     
     
         5 . The method of  claim 1  or  2  wherein the organic solvent is said carboxylic acid. 
     
     
         6 . The method of  claim 1  or  2  wherein the catalyst is an enzyme capable of esterifying the carboxylic acid with the diol to form diol esters of the carboxylic acid. 
     
     
         7 . The method of  claim 6  wherein the enzyme is selected from the group consisting of an esterase, a lipase, a phospholipase, and a lysophospholipase. 
     
     
         8 . The method of  claim 1  or  2  wherein the hydrolyzing of the diol ester is in the presence of a hydrolysis catalyst. 
     
     
         9 . The method of  claim 8  wherein the hydrolysis catalyst is selected from the group consisting of an acid catalyst, an organic acid, a water soluble acid, a water insoluble acid, and base and an enzyme capable of hydrolyzing the diol esters to form a carboxylic acid and a diol. 
     
     
         10 . The method of  claim 9  wherein the enzyme is an esterase, lipase, phospholipase, or lysophospholipase. 
     
     
         11 . The method of  claim 1  or  2  wherein contacting is in a fermentation product broth wherein the fermentation product broth has been processed to remove the fermentative microorganism, and optionally any additional undissolved solids. 
     
     
         12 . The method of  claim 1  or  2  wherein contacting is in a fermentation product broth wherein the fermentation product broth has been processed to reduce protease activity in the broth. 
     
     
         13 . The method of  claim 1  or  2  wherein the diol is selected from the group consisting of 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2,3-butanediol. 
     
     
         14 . The method of  claim 2  wherein solids are separated from the feedstock slurry prior to step (c). 
     
     
         15 . The method of  claim 1  or  2  wherein the carboxylic acid is obtained by hydrolysis of oil to carboxylic acid, wherein the oil is an oil stream separated from feedstock slurry or is a native oil. 
     
     
         16 . The method of  claim 15  wherein conversion to a carboxylic acid is by a catalyst that is an enzyme capable of esterifying the carboxylic acid with a diol to form diol esters of the carboxylic acid. 
     
     
         17 . The method of  claim 16  wherein the enzyme is an esterase, lipase, phospholipase, or lysophospholipase. 
     
     
         18 . The method of  claim 15  wherein at least a portion of the oil is converted to glycerol which is used in diol production. 
     
     
         19 . The method of  claim 1  or  2  wherein the carboxylic acid comprises at least one fatty acid. 
     
     
         20 . The method of  claim 19  wherein the fatty acid is corn oil fatty acid, soya oil fatty acid, or a mixture of corn oil fatty acid and soya oil fatty acid. 
     
     
         21 . The method of  claim 14  wherein the solids are processed to form to an animal feed product.