The role of myo-inositol in metabolic control. 3. The effects of carbon sources on myo-inositol deficiency of Saccharomyces carlsbergensis 4228 (ATCC 9080).

Abstract

1. The effects of carbon sources on growth, acetoin formation, respiration and fermentation of Saccharomyces carlsbergensis were examined in relation with myo-inositol (m-I) deficiency. Among five fermentable sugars tested (glucose, galactose, fructose, sucrose and mannose) galactose was unique in receiving very little effect of m-I deficiency ; no growth depression, much less O2 uptake inhibition and almost negligible accumulation of acetoin. A cyclization of galactose to m-I without conversion to glucose is suggested. 2. There existed a close correlation between the inhibition of growth or O2 uptake and acetoin formation, namely the larger the inhibition of growth or respiration the higher the acetoin accumulation took place. RD mutant of Saccharomyces carlsbergensis, however, did not produce much acetoin in the absence of m-I. m-I deficiency thus seems to be manifested when the respirative activities are repressed. 3. The effect of carbon sources on m-I deficiency of the yeast were also reproducible with cell suspensions prepared from the yeast grown on each sugar mentioned above. Pyruvate could also be used as substrate though the formation of acetoin was less.