Table 2.
Concentrations of substrate and products of 100-ml batch fermentations of C. acetobutylicum harboring pMTL500E, pWUR459, or pWUR460 on MG medium after 145 h
| Substrate or product concn or yielda | Value for parameter for C. acetobutylicum carrying the following plasmidb: |
||
|---|---|---|---|
| pMTL500E (control) | pWUR459 (Padc-Cb-acr) | pWUR460 (Pthl-Cb-acr) | |
| Substrate concns (mM) | |||
| Consumed glucose | 318 ± 15 | 307 ± 29 | 320 ± 18 |
| Initial acetic acidc | 37 ± 0.2 | 38 ± 0.4 | 36 ± 0.8 |
| Final acetic acid | 14 ± 0.7 | 20 ± 6 | 19 ± 2 |
| Concns of 2,3-BD pathway products (mM) | |||
| Acetoin | 19 ± 2 | 2 ± 1 | 3 ± 0.3 |
| meso-2,3-Butanediol | 3 ± 0.1 | 2 ± 0.1 | 2 ± 0.3 |
| d-2,3-Butanediol | 0 | 20 ± 1 | 22 ± 3 |
| Acetoin + 2,3-BD | 22 ± 2 | 25 ± 2 | 26 ± 4 |
| % yield of acetoin + 2,3-BD per glucose (mM/mM) | 7 ± 0.8 | 8 ± 0.9 | 8 ± 1 |
| Concns of other fermentation products (mM) | |||
| Butyric acid | 2 ± 1 | 5 ± 3 | 6 ± 3 |
| Lactic acid | 3 ± 0.7 | 6 ± 1 | 4 ± 0.4 |
| Acetone | 80 ± 9 | 78 ± 12 | 86 ± 6 |
| Butanol | 161 ± 6 | 157 ± 15 | 166 ± 6 |
| Ethanol | 40 ± 2 | 34 ± 5 | 56 ± 14 |
a
Abbreviation: 2,3-BD, 2,3-butanediol.
b
Data are given as the means ± standard deviations of three replicate fermentations.
c
Acetate is present at the beginning (time zero) as a medium component and is consumed during the fermentation.