Enhanced β-galactosidase production from whey powder by a mutant of the psychrotolerant yeast Guehomyces pullulans 17-1 for hydrolysis of lactose.

In order to isolate β-galactosidase overproducers of the psychrotolerant yeast Guehomyces pullulans 17-1, its cells were mutated by using nitrosoguanidine (NTG). One mutant (NTG-133) with enhanced β-galactosidase production was obtained. The mutant grown in the production medium with 30.

Disruption of the gene encoding β-1, 3-glucanase in marine-derived Williopsis saturnus WC91-2 enhances its killer toxin activity.

As the β-1, 3-glucanase produced by the marine-derived Williopsis saturnus WC91-2 could inhibit the activity of the killer toxin produced by the same yeast, the WsEXG1 gene encoding exo-β-1, 3-glucanase in W. saturnus WC91-2 was disrupted. The disruptant WC91-2-2 only produced a trace amount of β-1, 3-glucanase but had much higher activity of killer toxin than W.