Table 5 Statistics of Plackett–Burman data analysis indicating the coefficient, t-values, and P-values for each variable of the design

Intercept

226.875

43.67388

0.000524

pH

-13.8095

-1.02958

0.411432

58.86

Incubation time

30.71429

2.289925

0.149177

85.08

Temperature

-7.14286

-0.53254

0.647594

35.24

Glucose

78.45238

5.849071

0.028008

97.20

Peptone

-53.4524

-3.98518

0.057581

94.24

Beef extract

23.03571

1.862829

0.203521

79.65

Yeast extract

48.09524

4.629213

0.043633

95.64

K₂HPO₄

-17.0833

-1.38148

0.301221

69.88

Triammonium citrate

-32.7381

-2.44081

0.134745

86.53

Sodium acetate trihydrate

40.71429

3.035481

0.093549

90.65

MgSO₄.7H₂O

3.214286

0.239643

0.832928

16.71

Tween-80

-124.762

-9.30171

0.011361

98.86

Manganous sulfate tetrahydrate

8.452381

0.630173

0.592981

40.70