Table 1 Factors and their levels used in the optimization of IAA production by Rhizobium sp. using the central composite design
Symbol | Variables | Level 1 | Level 2 | Level 3 |
|---|---|---|---|---|
X1 | [L-tryptophan] (g/l) | 0.1 | 0.5 | 0.9 |
X2 | [NaCl] (g/l) | 0 | 2.5 | 5 |
X3 | Temperature (°C) | 30 | 36 | 42 |
X4 | pH | 4 | 6.5 | 9 |
X5 | Incubation time (days) | 1 | 8 | 15 |