Table 1.
The analysis of parameters at different culture conditions
| Parameters | Glycerol | Glucose | Glycerol/glucose co-fermentation (the molar ratio of glycerol to glucose was 4:1) | Fed-batch fermentation with glycerol/glucose co-fermentation |
|---|---|---|---|---|
| DCW (g l−1) | 3.3 ± 0.12 | 6.8 ± 0.19 | 4.9 ± 0.13 | 5.2 ± 0.11 |
| Propionic acid (g l−1) | 18.1 ± 0.65 | 11.5 ± 0.45 | 21.9 ± 0.72 | 29.2 ± 0.70 |
| Acetic acid (g l−1) | 0.54 ± 0.09 | 2.57 ± 0.12 | 0.87 ± 0.08 | 1.1 ± 0.15 |
| Succinic acid (g l−1) | 1.10 ± 0.05 | 0.55 ± 0.03 | 1.19 ± 0.04 | 1.57 ± 0.05 |
| Propanol (g l−1) | 1.02 ± 0.08 | ND | ND | ND |
| Propionic acid/acetic acid (mol mol−1) | 27.1 | 3.63 | 20.4 | 22.9 |
| Propionic acid yield (g g−1) | 0.475 ± 0.017 | 0.303 ± 0.012 | 0.572 ± 0.018 | 0.544 ± 0.012 |
| Propionic acid productivity (g l−1 h−1) | 0.108 | 0.068 | 0.152 | 0.152 |
| λ (lag time, h) | 4 | 6 | 2 | 2 |
| Substrate exhausted time (h) | 168 | 168 | 144 |
The average data of three independent experiments
ND None detected