Modified yeast consuming L-arabinose

Abstract

The present invention relates to a method for producing a L-arabinose utilizing yeast strain for the production of ethanol, whereby a yeast strain is modified by introducing and expressing araA gene (L-arabinose isomerase), araB gene (L-ribulokinase D 121 -N) and araD gene (L-ribulose-5-P 4-epimerase) and carrying additional mutations in its genome or overexpressing a TALl (transaldolase) gene, enabling it to consume L-arabinose, to use it as the only carbon source, and to produce ethanol, as well as a method for producing ethanol using such a modified strain.

1 . A method for producing an L-arabinose utilizing  Saccharomyces cerevisiae  yeast strain for the production of ethanol, wherein a yeast strain is modified by introducing and expressing an araA gene (L-arabinose isomerase), an araB gene (L-ribulokinase) and an araD gene (L-ribulose-5-P 4-epimerase), and carrying additional mutations in its genome or overexpressing a TALl (transaldolase) gene, enabling it to consume L-arabinose, and to produce ethanol thereby from a medium comprising L-arabinose, whereby the yeast strain is further modified by expressing a mutant form of the  E. coli  L-ribulokinase enzyme with reduced activity.  
     
     
         2 . The method according to  claim 1 , wherein the araA gene is a  B. subtilis  araA gene.  
     
     
         3 . The method according to  claim 1 , wherein the araA gene is a  M. smegmatis  araA gene.  
     
     
         4 . The method according to  claim 1 , wherein the araB gene is a  E. coli  araB gene.  
     
     
         5 . The method according to  claim 1 , wherein the araD gene is an  E. coli  araD gene.  
     
     
         6 . The method according to  claim 1 , wherein the TALl gene is an  S. cerevisiae  TALl gene.  
     
     
         7 . (canceled)  
     
     
         8 . The method according to  claim 1 , wherein the  Saccharomyces cerevisiae  strain is a CEN.PK strain, preferably a CEN.PK2-1C.  
     
     
         9 . The method according to  claim 1 , wherein the  Saccharomyces cerevisiae  strain is a  Saccharomyces cerevisiae  W303-strain.  
     
     
         10 . (canceled)  
     
     
         11 . The method according to  claim 1 , wherein the yeast strain is further modified by overexpressing the yeast GAL2 gene.  
     
     
         12 . The method according to  claim 1 , wherein the araB gene is placed behind a weak promoter.  
     
     
         13 . The method according to  claim 1 , wherein the modifications are made behind the strong HXT7 promoter fragment on multicopy vectors in  S. cerevisiae  CEN.PK-strains.  
     
     
         14 . The method according to  claim 1 , wherein the modifications are made behind the strong HXT7 promoter fragment on multicopy vectors in  Saccharomyces cerevisiae  W303-strains.  
     
     
         15 . The method according to  claim 1 , wherein the amount of L-arabinose of the growth medium is 2 to 200 g/L.  
     
     
         16 . The method according to  claim 1 , wherein the strain is  Saccharomyces cerevisiae  strain JBY25-4M with DSM accession number 15560.  
     
     
         17 . The method according to  claim 1 , wherein the strain is  Saccharomyces cerevisiae  strain JBY24-3T with a DSM accession number 15559.  
     
     
         18 . A method for producing ethanol by fermenting yeast, wherein a modified yeast according to  claim 1  ferments a growth medium containing L-arabinose.  
     
     
         19 . The method according to  claim 18 , wherein the amount of L-arabinose of the growth medium is 2 to 200 g/L.