Effect of oxygen and uracil on growth and energetic parameters of strains D39 and R6a.

aD39 and R6 were grown in CDM containing 61±1 mM glucose, with pH-controlled at 6.5, at 37°C, under different atmospheres (semi-aerobic, anaerobic or aerobic); to test the effect of uracil (U) on growth of both strains under semi-aerobic conditions, the nucleobase was added to a final concentration of 30 mg l−1.bGrowth phase at which samples were harvested for substrate and fermentation product analysis by HPLC; see text for details.cProduct yields, [End-product, mM]/[Glucose consumed, mM].dBlank cells, negative yields were found for these conditions (cells used pyruvate from the medium).eqsmax (substrate consumption rate) was estimated from a first-order derivative of a polynomial fit of the measured substrate consumption time series.fCarbon balance is the percentage of carbon in metabolized glucose that is recovered in the fermentation products (lactate, formate, acetate and ethanol) and pyruvate.Dry weight (DW) was used as a measure of cell mass. BDL, below detection limit of the HPLC technique; ND, not determined.Values of at least two independent experiments were averaged and errors are reported as ± SD.