Patent ID: 7507574

Claim:
A modified Saccharomyces cerevisiae yeast which produces lower levels of ethanol than wild-type yeast under aerobic conditions and glucose concentrations of 2%, and which exhibits a growth rate of at least 30% of the wild-type yeast, wherein said yeast contains a chimeric nucleotide sequence (a chimeric construct) which is stably transformed into the genetic material of the yeast, wherein the construct comprises a sequence having the form A-B wherein A is a first sequence comprising nucleotide bases w to x; B is a second sequence comprising nucleotide bases (x+y) to z; wherein A is from a nucleotide sequence encoding a Saccharomyces cerevisiae glucose transporter selected from HXT-1 (SEQ ID NO:22) or HXT-3 (SEQ ID NO:24) or encoding a sequence which exhibits at least 80% sequence identity to HXT1 (SEQ ID NO:22) or HXT-3 (SEQ ID NO:24), or the sequence complementary to any of the aforesaid sequences and B is from a nucleotide sequence encoding a Saccharomyces cerevisiae glucose transporter selected from HXT-2 (SEQ ID NO:23), HXT-4 (SEQ ID NO:25), HXT-6 (SEQ ID NO:26), HXT-7 (SEQ ID NO:27) or GAL2 (SEQ ID NO:28) or encoding a sequence which exhibits at least 80% sequence identity to HXT-2, HXT-4, HXT-6, HXT-7 or GAL-2, or the sequence complementary to any of the aforesaid sequences; w is a first position within the nucleotide sequence from which said first sequence is derived, and is from 1 to 10; x is a second position within the nucleotide sequence from which said first sequence is derived and is from 400 to 900; y is an integer less than 3; x+y is a first position within the nucleotide sequence from which said second sequence is derived; and z is a second position within the nucleotide sequence from which said second sequence is derived and is greater than x+y and is from 1600 to 1713; wherein said values refer to the position within the nucleotide sequence of said glucose transporter, and wherein said chimeric nucleotide sequence is introduced into a yeast cell which is a null strain which exhibits a glucose uptake of less than 2 nmol glucose/min/mg biomass to provide said modified Saccharomyces cerevisiae yeast.