Patent ID: 8574909

Claim:
A method for generating a strain of the yeast Saccharomyces cerevisiae comprising: a) providing a strain of Saccharomyces cerevisiae yeast, b) eliminating the function of all hexose transporters of said strain of yeast of step a) by mutating or deleting the relevant genomic sequences, c) transforming said strain of yeast of step b) with a GLUT1 gene in a yeast plasmid, d) subjecting said strain of step c) to mutagenesis wherein mutation allows the strain to grow on a medium with hexose as the only carbon source, said mutation not present in said GLUT1 gene, e) isolating a strain capable of growing on said substrate with hexose as the only carbon source, f) selecting yeast cells from said isolated strain yeast cells having no GLUT1 plasmid of step c), g) transforming said strain of step f) with a GLUT4 gene in a yeast plasmid, h) subjecting said strain of step g) to mutagenesis wherein mutation allows the strain to grow on a medium with hexose as the only carbon source, said mutation not present in said GLUT4 gene, i) isolating a second strain capable of growing on said substrate with hexose as the only carbon source, and j) selecting from the isolated second strain yeast cells having no GLUT4 plasmid of step g).