UTILIZATION OF INOSITOL, AN ESSENTIAL METABOLITE FOR SCHIZOSACCHAROMYCES POMBE

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Abstract
The yeast Schizosaccharomyces pombe has been shown by previous workers to have a requirement for meso-inositol. In our growth studies inositol disappeared from the medium at a rate commensurate with the growth rate until only a small amount (1-2%) remained. Analysis of cells and medium for inositol gave a recovery of 90-95% indicating that Hsis compound was not catabolized to any great extent. Much of the inositol within the yeast cells is bound to the lipid fraction. However, exhaustive extraction by fat solvents (alcohol-ester) (chloroform-methanol) failed to remove all the inositol containing compounds. This remaining inositol is not liberated from the cells by proteolytic enzymes. A "bound" form of inositol appears in the growth medium at the end of log phase of growth. It is assumed this results from autolysis of cells. Evidence for this is presented. This bound from is unavailable to the cells. Tests for phytin and certain cephalin like compounds containing inositol in these yeasts were negative.