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Table 5 Estimated effects and coefficients of the response values of PBD experiment

From: Optimization of fermentation conditions for surfactin production by B. subtilis YPS-32

Item

Effect

Coefficient

Standard error of coefficient

t-value

p-value

Constant

 

0.36931

0.00186

198.43

0.003

Molasses (g·L− 1)

-0.00506

-0.00253

0.00186

-1.36

0.404

Glutamic acid (g·L− 1)

0.00483

0.00242

0.00186

1.3

0.418

Soybean meal (g·L− 1)

0.00461

0.00231

0.00186

1.24

0.432

KCl (g·L− 1)

0.03894

0.01947

0.00186

10.46

0.061

K2HPO4 (g·L− 1)

-0.01339

-0.00669

0.00186

-3.6

0.173

MgSO4 (g·L− 1)

0.04739

0.02369

0.00186

12.73

0.05

Time (h)

0.07061

0.03531

0.00186

18.97

0.034

pH

-0.01417

-0.00708

0.00186

-3.81

0.164

Temperature (℃)

0.08683

0.04342

0.00186

23.33

0.027

Inoculum size (%)

-0.01572

-0.00786

0.00186

-4.22

0.148