No abstract

No abstract

The effect of inoculum preparation on the fully-aerated batch growth of Saccharomyces cerevisiae on glucose is described. The time allowed for inoculum adaptation and the conditions under which adaptation occurred, were observed to have a significant effect on the major metabolic variables: growth rate, specific sugar uptake rate, specific ethanol production rate, specific oxygen uptake rate, specific carbon dioxide production rate, the biomass yield, and the ethanol yield. Adaptation was allowed to occur under conditions of limited aeration (in shake flasks) and under defined aerobic conditions (DOT > 75°c saturation). With increasing time, differences in the extent of fermentation and respiration were found. Adaptation in shake flasks resulted in a significant increase in the fermentation capacity of the yeast, while adaptation under strongly aerobic conditions resulted in an increase in the respiratory capacity. These results suggest that inoculum preparation is a significant variable which can be manipulated to obtain varying growth characteristics under fully aerobic batch growth conditions. The growth characteristics of Saccharomyces cerevisiae in batch culture are influenced by the conditions to which the yeast is subjected, before it is used as a starter culture. Factors reported to have an effect are; the carbon source (1-6), the sugar concentration (4, 7), the physiological age of the culture (7, 8), the extent of aeration (7,9,10), and the inoculum level (11). Respiratory adaptation first described in 1950 (12) has been widely reported in the literature. Broadly, respiratory adaptation can be defined as the changes in enzymes and co-factors, induced by oxygen, which accelerate oxygen uptake. The increase in oxygen consumption or respiratory capacity have been ascribed to an adaptive synthesis of cytochAddress reprint requests to:

No abstract

No abstract