Table 3 Summary of bioethanol production from immobilized cells and free cells in repeated batch fermentation with 100 g/l glucose at 42 °C for 40 h per batch
Immobilization | Batch | Ethanol conc. (g/l) | Ethanol yields (% of the theoretical yield) | Ethanol productivity (g/l/h) | Statistical p values |
|---|---|---|---|---|---|
Free cells | 1 | 36.9 ± 2.4 | 72.2 ± 4.7 | 0.9 ± 0.1 | – |
2 | 40.6 ± 0.8 | 79.5 ± 1.6 | 1.0 ± 0.0 | – | |
3 | 42.1 ± 1.7 | 82.5 ± 3.3 | 1.1 ± 0.0 | – | |
4 | 42.5 ± 1.4 | 83.1 ± 2.7 | 1.1 ± 0.0 | – | |
Corncobs | 1 | 42.1 ± 0.7 | 82.4 ± 1.4 | 1.1 ± 0.0 | 0.0004*** |
2 | 42.3 ± 1.1 | 82.7 ± 2.2 | 1.1 ± 0.0 | 0.01* | |
3 | 42.6 ± 2.2 | 83.4 ± 4.3 | 1.1 ± 0.1 | 0.7, ns | |
4 | 44.5 ± 1.9 | 87.1 ± 3.7 | 1.1 ± 0.0 | 0.06, ns | |
Coconut wastes | 1 | 44.9 ± 0.5 | 87.9 ± 1.0 | 1.1 ± 0.0 | 0.00001*** |
2 | 44.4 ± 2.2 | 86.9 ± 4.3 | 1.1 ± 0.1 | 0.003** | |
3 | 41.4 ± 2.2 | 81.0 ± 4.3 | 1.0 ± 0.1 | 0.5, ns | |
4 | 36.0 ± 2.6 | 70.5 ± 5.1 | 0.9 ± 0.1 | 0.0004*** | |
Calcium alginate beads | 1 | 38.3 ± 1.2 | 74.9 ± 2.3 | 1.0 ± 0.0 | 0.2, ns |
2 | 39.4 ± 1.4 | 77.0 ± 2.7 | 1.0 ± 0.0 | 0.08, ns | |
3 | 42.2 ± 2.0 | 82.6 ± 3.9 | 1.1 ± 0.1 | 1.0, ns | |
4 | 34.9 ± 1.7 | 68.3 ± 3.3 | 0.9 ± 0.0 | 0.000008*** |