End products and fermentation balances for lactic streptococci grown aerobically on low concentrations of glucose

Abstract

Maximum acetate produced aerobically by S. diacetilactis and S. cremoris was 14% of 1 to 7 μmol of glucose/ml in a partially defined medium that contained lipoic acid. Y (glucose) values were 35.3 (S. diacetilactis) and 31.4 (S. cremoris) with low concentrations (1 to 7 μmol/ml) of glucose in the medium and 21 (S. diacetilactis) with higher concentrations (6 to 15 μmol/ml). Y (adenosine 5' triphosphate) values for the bacteria, determined by taking into account the end products produced, were 15.6 and 13.9 for S. diacetilactis and S. cremoris, respectively, in the partially defined medium containing 1 to 7 μmol of glucose/ml and higher (21.5 and 18.9, respectively) in a complex medium that contained 2 μmol of glucose/ml. Addition of citrate in addition to glucose did not result in higher molar growth yields.