Sf. Vincent et al., Comparison of melibiose utilizing baker's yeast strains produced by genetic engineering and classical breeding, LETT APPL M, 28(2), 1999, pp. 148-152
Yeast strains currently used in the baking industry cannot fully utilize th
e trisaccharide raffinose found in beet molasses due to the absence of meli
biase (alpha-galactosidase) activity. To overcome this deficiency, the MEL1
gene encoding melibiase enzyme was introduced into baker's yeast by both c
lassical breeding and recombinant DNA technology. Both types of yeast strai
ns were capable of vigorous fermentation in the presence of high levels of
sucrose, making them suitable for the rapidly developing Asian markets wher
e high levels of sugar are used in bread manufacture. Melibiase expression
appeared to be dosage-dependent, with relatively low expression sufficient
for complete melibiose utilization in a model fermentation system.