Table 1 Comparison of cell growth, sporulation and δ-endotoxin production by Bacillus thuringiensis MPK13 in batch and fed-batch cultivations
Fermentation mode | Max cell count (× 1011 CFU/ml) | Max spore count (× 1011 spore/ml) | Increase in cell count (%)a | Decrease in spore count (%)b | δ-endotoxin | Max percentage of sporulation (%) | Max cell productivity (× 108 CFU/l/h) | Max spore productivity (× 108 spore/l/h) |
|---|---|---|---|---|---|---|---|---|
Batch | 13.9 (48 h) | 5.2 (48 h) | 0 | 0 | Yes (36 h) | 37 (48 h) | 72.4 | 24.5 |
Fed-batch Feed during: | ||||||||
1) Lag phase (2 h) | 14.7 (48 h) | 3.7 (48 h) | 5.8 | 28.8 | Yes (48 h) | 25 (48 h) | 73.4 | 19.3 |
2) Log phase (6 h) | 15.8 (40 h) | 3.9 (48 h) | 13.7 | 25.0 | Yes (48 h) | 25 (48 h) | 98.8 | 20.3 |
3) Stationary phase (24 h) | 16.1 (48 h) | 3.1 (48 h) | 15.8 | 40.0 | No | 21.5 (24 h) | 83.9 | 16.1 |
Intermittent fed-batch | 17.2 (48 h) | 2.6 (48 h) | 23.7 | 50.0 | No | 15.2 (36 h) | 89.6 | 13.5 |