Utilization of inositol, an essential metabolite for Schizosaccharomyces pombe.

Mlanv workers have found mn-inositol to be a growth factor for certain animals and microorganisms. Interest in this compound as a growth factor for y-east was stimulated by Eastcott (1928) when she found m-inositol to be one of the fractions of "Bios." Since that time yeasts have been extensively investigated in regards to their iequirements for this compound. Several species have been proposed as assay organisms for m-inositol. Schizosaccharomyces pombe is one that has an absolute requirement for m-inositol; i. e., no measurable growth occurs in the absence of this compound. This requirement for the meso or optically inactive form has been shown to be quite specific (Woolley, 1941a; Schopfer, 1944; Schopfer et al., 1948). Since this yeast is incapable of synthesizing inositol to any degree, it can be used to study the fate of inositol supplied in the medium. The correlation of growth and inositol uptake by S. pombe has been measured. An attempt was made to determine the distribution of inositol and inositol compounds in the yeast cell and the medium. Ai\uch of the inositol appears in the cells in compounds which are extractable with fat solvents. Compounds of inositol in 'the medium in which cells were grown appear not to be soluble in fat solvents. The nature of these compounds was not determined.