Table 4.

The estimated coefficients for B. subtilis B.S.46 phytase activity.

Source	Coefficient	Standard error	F-value	P-value
Intercept	4.35	0.052
X1 – Temp.	−0.23	0.054	18.54	0.0051
$X_2$ – pH	−0.48	0.054	77.78	0.0001
$X_3$ – Conc.	0.54	0.054	100.69	<0.0001
$X_1{X}_2$	0.12	0.045	6.94	0.0389
$X_1{X}_3$	−0.12	0.045	7.38	0.0348
$X_2{X}_3$	0.17	0.045	13.61	0.0102
$X_1^2$	−1.12	0.034	1086.15	<0.0001
$X_2^2$	−1.14	0.034	1126.77	<0.0001
$X_3^2$	−0.64	0.034	354.01	<0.0001
$X_1{X}_2{X}_3$	0.31	0.045	46.71	0.0005
$X_1^2{X}_2$	−0.27	0.071	14.97	0.0083
$X_1^2{X}_3$	−0.77	0.071	119.75	<0.0001