Table 2 Comparison of cell growth, sporulation, and δ-endotoxin production by Bacillus thuringiensis MPK13 in fed-batch cultivation with the optimal DOT control strategy
Fed-batch with aeration strategy | Max cell count (× 1011 CFU/ml) | Max spore count (× 1011 spore/ml) | Increase in cell count (%)a | Increase in spore count (%)b | δ-endotoxin | Max percentage of sporulation (%) | Max cell productivity (× 1011 CFU/l/h) | Max spore productivity (× 1011 spore/l/h) |
|---|---|---|---|---|---|---|---|---|
Medium feeding at lag growth phase (2 h) (DOT was switched from 80% to 40% at 8 h of cultivation) | 14.7 (48 h) | 6.6 (48 h) | 5.8 | 26.9 | Yes (24–48 h) | 45.9 (48 h) | 76.6 | 30.2 |
Medium feeding at exponential growth phase (6 h) (DOT was switched from 80% to 40% at 12 h of cultivation) | 14.5 (48 h) | 7.1 (48 h) | 4.3 | 36.5 | Yes (28–48 h) | 49.0 (48 h) | 75.5 | 37.0 |