Transformed eukaryotic cells that directly convert xylose to xylulose

A process for producing a non-ethanolic fermentation product fermentation product, which process comprises the steps of:

• (a) fermenting a 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
• which nucleotide sequence is operative linked to a promoter that drives active expression of the xylose isomerase coding sequence in the transformed cell,
• (ii) expresses one or more enzymes that confers on the cell the ability to produce a non-ethanolic fermentation product,
• wherein, expression of the construct confers on the cell the ability to directly ferment and isomerize xylose to xylulose and thereby produce said non-ethanolic fermentation product;
• and
• (b) optionally, recovering the non-ethanolic fermentation product from said medium.

A cultured yeast cell transformed with a nucleic acid expression construct which construct comprises:

• (a) a nucleotide sequence that encodes xylose isomerase protein, the amino acid sequence of which
• (i) is at least 950o identical with SEQ ID NO:1,
• (ii) comprises a first xylose isomerase signature pattern;
• (iii) comprises a second xylose isomerase signature pattern;
• (iv) 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;
• (v) comprises at least one Mg-binding site that is residue Glu 233 of SEQ ID NO:1;
• and
• (b) 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, said expression construct is expressible in said cell and expression thereof confers on the cell the ability to directly isomerize xylose to xylulose.