Modification by Hexitols and Sugars of Changes Induced in Yeast by Starvation. I. Differences in CO2 Production, O2 Use and Viability

摘要

Incubation of yeast cells for 21 hours in solutions of certain sugars and hexitols, including ribose, cellobiose, glucose, sorbitol and mannitol, produced cells capable of forming CO2 from glucose at a high rate and without an initial lag. This result contrasted markedly with a lag in output and a lower rate of CO2 output by cells incubated in water, i.e., starved. Incubation with other sugars and with other compounds, including amino acids, purines and pyrimidines, and organic and inorganic salts, was not effective in preserving CO2 output or reducing it. Usability of the compounds, measured by cell growth or by O2 uptake, was not correlated with the capacity to preserve CO2 output, though readily metabolized sugars at higher concentrations evidently caused an added loss of cell materials and reduced viability. Effective sugars functioned when included with ineffective compounds. Hexitols did not compete in this fashion and did not convert cells as rapidly as sugars to a condition which allowed them later to produce CO2 at a high rate. Oxygen uptake on different substrates was increased after some incubations, but viability was not increased above that of cells incubated in water. Materials lost from the cells during incubation were not identified as cofactors by the supplementation experiments carried out, though general stimulations were obtained. (Author)