INULASE-SECRETING STRAIN OF SACCHAROMYCES-CEREVISIAE PRODUCES FRUCTOSE

The gene encoding inulase of the yeast Kluyveromyces marxianus (INU1(k m)) was cloned and expressed in the inulin-negative yeast Saccharomyce s cerevisiae. Cells of S. cerevisiae transformed with the INU1(km) gen e have acquired extracellular inulase activity and were able to grow i n the medium with inulin as a sole carbon source. The S. cerevisiae st rain was constructed that is capable of heterologous expression of sec reted 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 accumulati ng at least 10% glucose-free fructose in the culture liquid. (C) 1998 John Wiley & Sons, Inc.