Table 1 Independent variables with their respective levels for a fractional factorial design of laccase production (U L− 1) from V. salarius.
Independent variable | Unit | Symbol | Coded variable level | ||
|---|---|---|---|---|---|
Low (− 1) | Medium (0) | High (+ 1) | |||
Sodium chloride | M | X1 | 1 | 2 | 3 |
pH | X2 | 6 | 7 | 8 | |
Temperature | °C | X3 | 25 | 35 | 45 |
Inoculum size | % | X4 | 1 | 2 | 3 |
Medium-to-air ratio | X5 | 1:10 | 2:10 | 3:10 | |
Glucose | % | X6 | 0.5 | 1 | 1.5 |
Peptone | % | X7 | 0.5 | 1 | 1.5 |
Ferrous sulfate | mM | X8 | 0.5 | 1 | 1.5 |
Copper sulfate | mM | X9 | 3 | 5 | 7 |
