TABLE 2.

Growth rates, substrate consumption rates, final l-valine concentrations, and productivity of C. glutamicum ΔaceE Δpqo(pJC4ilvBNCE) in shake flask fermentations

Substrate (concn [%])aGrowth rate (h−1)bSubstrate consumption rate [mmol C/ (g CDW × h)]cl-Valine concn (mM)dYP/S (g C/g C)eProductivity [mmol/ (g CDW × h)]f
AcetateGlucoseMaltose
Glucose (4.5) + acetate (2)0.20 ± 0.025.09 ± 0.080.13 ± 0.18NDg86 ± 20.23 ± 0.010.17 ± 0.01
Maltose (4.5) + acetate (2)0.27 ± 0.012.25 ± 0.41ND3.53 ± 0.9371 ± 40.19 ± 0.030.17 ± 0.01
Glucose (4) + maltose (0.5) + acetate (2)0.27 ± 0.012.80 ± 0.223.78 ± 1.101.72 ± 0.15102 ± 20.21 ± 0.010.27 ± 0.02
Glucose (3.5) + maltose (1) + acetate (2)0.28 ± 0.021.97 ± 0.173.25 ± 0.502.92 ± 0.2594 ± 50.17 ± 0.020.26 ± 0.01
  • a All percentages are in wt/vol.

  • b Growth rate was calculated for the exponential phase for the first 12 h of fermentation.

  • c CDW was calculated from the OD600 (after 12 h) by using a ratio of 0.3 g CDW liter−1 per unit of OD600 (4). Substrate consumption was calculated for acetate, glucose, and maltose for the first 12 h of fermentation.

  • d The l-valine concentrations are given for the mixture of glucose plus acetate after 48 h and for maltose plus acetate and for glucose plus maltose plus acetate after 24 h.

  • e Substrate specific yields (YP/S) are given as grams of carbon in l-valine per gram of carbon of the consumed substrates (acetate, glucose, maltose). The yields are calculated for the same time points as the l-valine concentrations.

  • f The productivities are given for the same time points as the l-valine concentrations.

  • g ND, not detected.