DEATH OF YEAST CELLS IN PANTOTHENIC ACID DEFICIENCY

Investigations were made on the dead cell formation in the growth of the baker's yeast in pantothenate deficiency and the concomitant occurrence of a variant strain which can grow better at lower concentrations of pantothenate.1. The rate of dead cell formation varied with the kind of amino acids present in the medium at a certain concentration of pantothenate. Methionine and leucine were most effective in producing the dead cells even at a comparatively high concentration of pantothenate. At lower pantothenate concentrations, addition of various amino acids induced marked production.2. The dead cells were produced even at an early stage of growth.3. When the yeast cells were incubated for 2 or more days in a medium, possible in producing a large number of dead cells, a variant strain always appeared. The variant strain can grow better even at very low concentrations of pantothenate, but shows longer lag phase and slightly poorer growth than do the original one, when a sufficient amount of pantothenic acid was supplied.4. According to electron microscopic observation, the walls of the dead cells produced in pantothenate deficiency were slightly thicker than those of pantothenate-sufficient cells.