Table 2 The level of factors, their codes, and actual values involved in central composite design
Code | Independent variables | Low (-1) | Central (0) | High (+ 1) |
|---|---|---|---|---|
A | pH | 6.0 | 7.0 | 8.0 |
B | Yeast extract (g L− 1) | 3.86 | 7.73 | 11.25 |
C | NaCl (g L− 1) | 125 | 200 | 275 |
D | Inoculum volume | 1 | 5.5 | 10 |
E | Incubation time (days) | 3 | 6 | 9 |