PHYSIOLOGICAL REQUIREMENTS FOR INDUCTION OF SPORULATION IN LAGER YEAST*

A study of the effects on sporulation of temperature and of presporulation growth on several carbon sources has led to the identification of physiological conditions for a marked improvement of ascosporogenesis in lager yeast. Sporulation occurred only on incubation of both presporulation and sporulation cultures at 21°C. Experiments in which sporogenic abilities were monitored at various stages in the growth curve demonstrated maximum ascus production in sporulation medium inoculated with acetate-grown cells harvested from stationary rather than exponential phase. Increasing the potassium acetate concentration in sporulation medium gave further increases in total sporulation and a marked induction of tetrad production. Several differences in spore morphology were found between ale and lager strains studied and physiological requirements for optimal sporulation were compared.