The effect of CO₂ on the absorption of amino acids from a malt extract medium by Saccharomyces cerevisiae

Fermentation of a malt extract medium under a constant CO₂ pressure of 1.97 bar at 25°C resulted in a changed pattern of absorption of amino acids during the first 4 h followed by a general excretion of amino acids thereafter. In the early, phase, some amino acids were not absorbed at all, some were absorbed more rapidly or more slowly than in the control and absorption of others seems unaffected. The cells grown under CO₂ had a lower protein content and viability but higher nucleic acid and free amino acid content than the control cells. The volume of CO₂-treated cells was also substantially increased.