Inulase‐secreting strain of Saccharomyces cerevisiae produces fructose

Abstract

The gene encoding inulase of the yeast Kluyveromyces marxianus (INU1Km) was cloned and expressed in the inulin-negative yeast Saccharomyces cerevisiae. Cells of S. cerevisiae transformed with the INU1Km gene have acquired extracellular inulase activity and were able to grow in the medium with inulin as a sole carbon source. The S. cerevisiae strain was constructed that is capable of heterologous expression of secreted K. marxianus inulase and is defective in fructose uptake due to null-mutations of the hexokinase structural genes HXK1 and HXK2. When grown in inulin-containing media, this strain is capable of accumulating at least 10% glucose-free fructose in the culture liquid.

Glucose-free fructose production from Jerusalem artichoke using a recombinant inulinase-secreting Saccharomyces cerevisiae strain

“…The inulinase-secreting hxkD yeast constructed in this study can grow normally in Jerusalem artichoke tubers medium without supplementation to produce glucose-free fructose. The fermentation time for fructose production is shorter than that reported by Brevnova et al (1998).…”

“…The recombinant yeast's ability of producing glucose-free fructose was studied and the medium they used was rich YEP medium supplemented with inulin, ethanol and glycerol, which is costly and unpractical for fructose production. Different from the method of Brevnova et al (1998), we introduced an episomal vector carrying the kcinu gene expression cassette under the control of original kcinu gene promoter and signal peptide sequence into S. cerevisiae strain Y16. The kcinu gene carrying the vector in host cells with multi-copy is favorable for high-level expression of inulinase.…”