Table 7.
Comparison experiments using optimized skim milk and yeast extract based on biomass production, β-galactosidase production, lactose, and free amino nitrogen residual at 21 h of cultivation period.
| Skim milk (% wt/vol)* | Biomass production (log10 cfu/mL) | β-Galactosidase production (U/mL) | Lactose (g/L) | Free amino nitrogen (mg/L) |
|---|---|---|---|---|
| 0 | 1.03 ± 0.11a∗∗ | 0.35 ± 0.21a | 0.00 ± 0.00a | 141.57 ± 18.90a |
| 4 | 7.19 ± 0.07b | 6.36 ± 0.16b | 7.25 ± 2.02b | 153.80 ± 15.46a |
| 7.17 (optimized concentrations) | 7.35 ± 0.06b | 6.34 ± 0.08b | 15.92 ± 3.23c | 198.73 ± 13.67a |
| 10 | 7.78 ± 0.55b | 5.54 ± 1.02b | 21.39 ± 3.29c | 251.57 ± 18.71b |
| 12 | 7.52 ± 0.63b | 5.23 ± 0.56b | 25.98 ± 3.19c | 282.27 ± 11.13b |
| TPY | 7.79 ± 0.45b | 0.05 ± 0.11a | 0.00 ± 0.00a | 374.20 ± 16.22c |
*Cultivation was conducted in different concentrations of skim milk with 1.02% yeast extract supplementation.
**Values in the same column with different letters were significantly different (P < 0.05).