Effects of pretreatments with sulfhydryls and alkylating agents on spheroplast formation from Schwanniomyces species

Abstract

Pretreatment of cells with β-mercaptoethanol, dithiothreitol, or cysteine increased the rate of spheroplast formation at all stages of growth in Schwanniomyces castellii and S. occidentalis, but had little effect on final yields of spheroplasts when compared with controls. Pretreatment with iodoacetate and cystine resulted in decreased rates of formation and lower yields of spheroplasts at all stages of growth for both species. The enhanced rates of spheroplast formation in the presence of the sulfhydryl compounds were more pronounced when the experimental cells were derived from early or late stationary phase cultures, whereas the inhibitory effects of cystine and iodoacetate were not associated with the growth phase. In agreement with extant data on other yeast genera, sulfhydryl compounds increased the susceptibility of the yeast cell wall to degradative enzymes, whilst alkylating agents decreased susceptibility of cell walls to these enzymes.