Construction of industrial baker's yeast strains able to assimilate maltose under catabolite repression conditions

Spore progeny from an industrial baker's yeast strain were mutagenized with UV and mutants resistant to 2-deoxyglucose isolated. One of these mutants (10a12–13) showed high levels of maltase (-glucosidase) and external invertase, and assimilated maltose when growing under catabolite repression conditions. This mutant was not allelic to any of the catabolite repression mutants tested cat4, cat80, cid1, cyc8, hex2, hxk2 and tup1. Mutant 10a12–13 was crossed with appropriate strains to construct hybrids that were also able to assimilate maltose in the presence of glucose. These hybrids may be useful in fermentation processes where both glucose and maltose are present.