The utilization of carbon sources by certain yeast strains

Abstract

The growth characteristics of strains of Saccharomyces cerevisiae with different carbon substrates have been studied. The strains examined were able to grow with all the substrates tested, except for one aneurin-exacting strain which failed to metabolize oxalacetic, aconitic, citric and $\alpha $-$\text{ketoglutaric acidsn}$. Adaptation takes place upon successive subculturing in these substrates. The behaviour observed is compared with that of a typical bacterium, Bact. lactis aerogenes, in the same substrates. Training to some of the substrates may afford adaptation to certain other substrates. The relations found are not all in accordance with expectations based upon the tricarboxylic acid cycle. Some of the strains required training for optimum utilization of glucose. The effect of this training upon their behaviour in a first subculture into acids of the tricarboxylic acid cycle has been examined. The use of the tricarboxylic acid cycle as a route for glucose metabolism in yeast is considered in the light of the experimental evidence, and the conclusion is reached that this cycle is only one of two or more routes forming an interlocking network by means of which carbon sources can be metabolized in the organism.