Ethanol production from lignocellulose

Abstract

This invention presents a method of improving enzymatic degradation of lignocellulose, as in the production of ethanol from lignocellulosic material, through the use of ultrasonic treatment. The invention shows that ultrasonic treatment reduces cellulase requirements by ⅓ to ½. With the cost of enzymes being a major problem in the cost-effective production of ethanol from lignocellulosic material, this invention presents a significant improvement over presently available methods.

What is claimed is:  
     
         1 . A method for enzymatically degrading lignocellulose comprising the steps of: 
 (a) subjecting an aqueous mixture containing lignocellulose with ultrasound; and    (b) contacting the mixture with a cellulase under conditions sufficient for hydrolysis.    
     
     
         2 . The method according to  claim 1  wherein said aqueous mixture of step (a) further comprises said cellulase.  
     
     
         3 . The method according to  claim 2  wherein said cellulase is provided by a cellulase-producing microorganism in said aqueous mixture.  
     
     
         4 . The method according to  claim 2  wherein said step (a) is continuous.  
     
     
         5 . The method according to  claim 2  wherein said step (a) is discontinuous.  
     
     
         6 . The method according to  claim 1  wherein said ultrasound is conducted at a frequency of between about 2 and 200 kHz.  
     
     
         7 . A method for enzymatically degrading lignocellulose comprising the steps of: 
 (a) subjecting an aqueous mixture containing lignocellulose with ultrasound; and    (b) contacting the mixture with a cellulase and ethanologenic microorganism under conditions sufficient for hydrolysis.    
     
     
         8 . The method according to  claim 7  wherein said aqueous mixture of step (a) further comprises said cellulase and ethanologenic microorganism.  
     
     
         9 . The method according to  claim 8  wherein said cellulase is provided by a cellulase-producing microorganism in said aqueous mixture.  
     
     
         10 . The method according to  claim 8  wherein said step (a) is continuous.  
     
     
         11 . The method according to  claim 8  wherein said step (a) is discontinuous.  
     
     
         12 . The method according to  claim 8  wherein said ultrasound is conducted at a frequency of between about 2 and 200 kHz.  
     
     
         13 . The method according to  claim 8  wherein said ethanologenic microorganism is an ethanologenic bacteria or yeast.  
     
     
         14 . The method according to  claim 13  wherein said ethanologenic microorganism is a bacteria or yeast which expresses one or more enzymes which, individually or together, convert a sugar to ethanol.  
     
     
         15 . The method according to  claim 13  wherein said ethanologenic microorganism expresses enzymes which, individually or together, convert pentose and hexose to ethanol.  
     
     
         16 . The method according to  claim 13  wherein said ethanologenic microorganism expresses alcohol dehydrogenase and pyruvate decarboxylase.  
     
     
         17 . The method according to  claim 16  wherein said alcohol dehydrogenase and pyruvate decarboxylase are from  Zymomonas mobilis.    
     
     
         18 . The method according to  claim 13  wherein said ethanologenic microorganism expresses xylose isomerase, xylulokinase, transaldolase, and transketolase.  
     
     
         19 . The method according to  claim 18  wherein said xylose isomerase, xylulokinase, transaldolase, and transketolase are from  Escherichia coli.    
     
     
         20 . The method according to  claim 18  wherein said xylose isomerase, xylulokinase, transaldolase, and transketolase are from  Klebsiella oxytoca.    
     
     
         21 . The method according to  claim 18  wherein said xylose isomerase, xylulokinase, transaldolase, and transketolase are from Erwinia species.  
     
     
         22 . The method according to  claim 13  wherein said ethanologenic microorganism expresses alcohol dehydrogenase, pyruvate decarboxylase, xylose isomerase, xylulokinase, transaldolase, and transketolase.  
     
     
         23 . The method according to  claim 22  wherein said ethanologenic microorganism is a recombinant microorganism expressing  Zymomonas mobilis  alcohol dehydrogenase and pyruvate decarboxylase wherein said microorganism is selected from the group consisting of  Escherichia coli, Klebsiella oxytoca,  and Erwinia species.  
     
     
         24 . The method according to  claim 23  wherein said ethanologenic microorganism is  Klebsiella oxytoca  P2.  
     
     
         25 . The method according to  claim 23 , wherein said ethanologenic microorganism is  Escherichia coli  KO11.