Table 1 The level of factors, their codes, and actual values involved in plackett-burman experiment design
Code | Factor (units) | Low (-1) | Central (0) | High (+ 1) |
|---|---|---|---|---|
X1 | Sucrose (g L− 1) | 0.5 | 2.0 | 3.5 |
X2 | Yeast extract (g L− 1) | 3.86 | 7.73 | 11.25 |
X3 | MgSO4·7H2O (g L− 1) | 10 | 35 | 60 |
X4 | pH | 6.0 | 7.0 | 8.0 |
X5 | Incubation time (days) | 3 | 6 | 9 |
X6 | Inoculum volume (%) | 1 | 5.5 | 10 |
X7 | KCl (g L− 1) | 2.0 | 4.0 | 6.0 |
X8 | CaCl2·6H2O (g L− 1) | 0.5 | 1 | 1.5 |
X9 | NaCl (g L− 1) | 125 | 200 | 275 |