Patent ID: 7622284

Claim:
A process for producing ethanol, comprising the steps of: (a) fermenting medium containing a source of xylose with a cultured yeast cell that (i) is transformed with a nucleic acid expression construct comprising a nucleotide sequence that encodes xylose isomerase protein, the amino acid sequence of which: (A) is at least 950% identical with SEQ ID NO:1, (B) comprises a first xylose isomerase signature pattern; (C) comprises a second xylose isomerase signature pattern; (D) comprises a catalytic triad including the following four residues at the indicated positions in SEQ ID NO: 1: His 102 plus Asp 105, and Asp 340 and Lys 235; (E) comprises at least one Mg-binding site that is residue Glu 233 of SEQ ID NO:1; and (ii) operative linked to the nucleotide sequence of (i), a promoter that drives active expression of the xylose isomerase coding sequence in the transformed cell, wherein the expression construct is expressible in said cell, and expression thereof confers on the cell the ability to directly isomerize xylose to xylulose, and thereby, to produce ethanol; and (b) optionally, recovering the ethanol from said medium.