Kvasny Prum. 1977; 23(1): 8-15 | DOI: 10.18832/kp1977002

Ethanol medium for yeast cultivation requiring no pH regulation.Peer-reviewed article

M. ŠESTÁKOVÁ, F. ŠTROS

The article deals with the cultivation of Candida utilis yeast in a mineral medium prepared of synthetic hydrogenated ethanol and containing various amounts of ammonium sulphate and urea as nitrogen sources. Having evaluated all relevant factors and processes as> growth rate of yeast, increase in yeast dry matter, speed of ethanol consumption and formation of its metabolic products }acetaldehyde, acetic acid and ethyl acetate], changes of pH taking place during fermentation in cultivation flasks of 500 ml capacity on a rotary shaking machine at 30 °C, the authors recommend for research of metabolism of Candida utilis under laboratory conditions the medium containing urea as the only source of nitrogen. Such a medium requires no pH regulation during the cultivation period and ensures maximum yields of yeast matter. Undersirable pH increase, which may take place after the substrate has been spent, can be prevented by balancing correctly the nitrogen to carbon proportion adjusting it to expected increase of biomass with 8,3% nitrogen content. In experiments dealt with in the article the optimum urea concentration was1,47 gper1 lof medium. Such concentration holds pH on a physiologically appropriate level and ensures 70% yield of dry yeast matter.
(In Czech, English summary only)

Keywords: yeasts, ethanol, medium, pH

Published: January 1, 1977