UNBALANCED GROWTH DEATH OF YEAST DUE TO PANTOTHENATE DEFICIENCY

[摘要] Pantothenate-requiring baker's yeast, Saccharomyces cerevisiae strain BA-1, died to a large extent when Casamino acids-containing medium was newly given to the pantothenate-deficient cells harvested in an arithmetic linear phase of growth. Methionine contained in the Casamino acids stimulated the cell death pronouncedly. To the pantothenate-deficient cells grown in the medium containing Casamino acids as the nitrogen source (CA medium), addition of NaCl or KCl at concentrations higher than 0.5M markedly prevented the cell death. In contrast, addition of sucrose or mannitol to the CA medium was ineffective in such a protective action. The number of dead cells decreased with elevation of pH values up to 7.5. The death of cells was not stimulated by the addition of EDTA over a wide range of from 10-4 to 3×10-2M. As to the effect of various long-chain fatty acids on the growth and death of cells, palmitic acid was the most effective for reduction of death ratio, and stearic acid was the second one, while unsaturated fatty acids showed much less effect. When the yeast was grown in a pantothenate- free CA medium, striking changes occurred in fatty acid composition of the cells. Although the cells incubated in the CA medium both with and without pantothenate consisted of the same kinds of fatty acids, the amounts of C16:1, C18:1, and especially C16:0 fatty acid were pronouncedly smaller in the cells grown without pantothenate. The differences between these results and those previously obtained about the cell death due to biotin deficiency were discussed.

[学科分类] 微生物学和免疫学