Xylose isomerase genes and their use in fermentation of pentose sugars

摘要

The present invention relates to eukaryotic cells which have the ability to isomerize xylose directly into xylulose by transformation with nucleotide sequences encoding a xylose isomerase that has one or more specific sequence elements typical for isomerases which are functionally expressed in yeasts, such as xylose isomerases obtainable from bacteria of the genera Clostridium and Fusobacterium or a tunicate from the genus Ciona. The cell preferably is a yeast or a filamentous fungus capable of anaerobic alcoholic fermentation. The cells may further comprise one or more genetic modifications that increase the flux of the pentose phosphate pathway or, reduce unspecific aldose reductase activity. The cell preferably has the ability to produce a fermentation product such as ethanol, lactic acid, 3-hydroxy-propionic acid, β-lactam antibiotics and cephalosporins. Also provided are processes for producing these fermentation products from xylose.

主权项

1. A yeast cell comprising a nucleic acid construct comprising a heterologous nucleic acid with a nucleotide sequence encoding a polypeptide that has xylose isomerase enzymatic activity, the expression of which polypeptide confers on, or increases in, the yeast cell the ability to directly isomerize xylose into xylulose, wherein the amino acid sequence of the polypeptide is at least 98% identical to SEQ ID NO:2 and comprises one or more conservative amino acid substitutions; wherein the one or more conservative amino acid substitutions is selected from the group consisting of valine to leucine or isoleucine, phenyalanine to tyrosine, lysine to arginine, alanine to valine, and asparagine to glutamine.