The present invention discloses
xylose isomerases obtained based on an ancestral sequence construction method and their applications. These
xylose isomerases are obtained based on the ancestral sequence construction method and have any of the
amino acid sequences ID NO. 1 to SEQ ID NO. 4. Expression of these
xylose isomerases alone or in combination can confer upon
yeast cells the ability to convert xylose to
xylulose, thereby conferring upon host cells the ability to convert xylose to other products. The present invention also relates to the application of these four xylose isomerases in
yeast production of chemicals such as
ethanol using xylose as a substrate. When expressed in
yeast cells such as
Saccharomyces cerevisiae, these xylose isomerases can confer upon a host
cell that originally lacks the ability to convert xylose to
xylulose this ability, conferring upon the host
cell the ability to produce chemicals such as
ethanol using xylose or lignocellulose
hydrolysate, which are rich in xylose.