Isolation and Characterization of Mutants of Saccharomyces cerevisiae Able to Sporulate in the Presence of Glucose

Abstract

Mutants of Saccharomyces cerevisiae able to sporulate in the presence of 1 % (w/v) glucose have been isolated. A single mutation, srgl, is responsible for this phenotype. One of the srgl mutants, A-20, was characterized biochemically. The mutants had generation times similar to that of the parental strain when growing with glucose or ethanol as carbon source, and on sporulation medium in the absence of glucose they behaved like the wild-type. In contrast, in the presence of glucose, mutant A-20 raised the pH of the medium and degraded glycogen after an initial period of accumulation. This behaviour was not observed in the wild-type. CAMP concentration increased in the mutant after addition of glucose, although to a lesser extent than in the parent. A marked difference between the mutant and the wild-type was the slow utilization of glucose by the mutant when placed in sporulation medium. In addition, in sporulation medium, the glucose uptake system was inactivated with different kinetics in the mutant compared with the wildtype. The srgl mutation seems therefore to affect the glucose uptake system.

Use of cereals as basal medium for the formulation of alternative culture media for fungi

“…Inocula were drawn from the pure cultures of the isolates just before 96th h of growth and aseptically inoculated onto all the formulated media and the control (PDA). The inocula were taken at that time to ensure that growth was still high at logarithmic phase when cells would have uniform physiological characteristics (Salmon et al 1989;Nwachukwu & Akpata 2003).…”