Carbon dioxide inhibition of yeast growth in biomass production

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Abstract
Saccharomyces cerevisiae was grown under aerobic and substrate-limiting conditions for efficient biomass production. Under these conditions, where the sugar substrate was fed incrementally, the growth pattern of the yeast cells was uniform, as indicated by a constant respiratory quotient during the entire growing period. The effect of CO2 was investigated by replacing portions of the N2 in the air stream with CO2, while maintaining the O2 content at the normal 20% level, so that identical O2 transfer rate and atmospheric pressure were maintained for all experiments with different partial pressures of CO2. Inhibition of yeast growth was negligible < 20% CO2 in the aeration mixture. Slight inhibition was noted at the 40% CO2 level, and significant inhibition was noted > the 50% CO2 level, corresponding to 1.6 .times. 10-2 M of dissolved CO2 in the fermentor broth. High CO2 content in the gas phase also inhibited the fermentation activity of baker''s yeast.