Table 1.

Significance analysis of eight variables for L-Met biosynthesis from the PB design results

Variable	Effect	Coef	SE Coef	T	F	P value Prob. > F
Model		1.0549	0.04111	25.66	9.11	0.000
x 1 (glucose)	0.4242	0.2121	0.04111	5.16	26.62	0.001***
x 2 ((NH4)2SO4)	− 0.1260	− 0.0630	0.04111	− 1.53	2.35	0.164
x 3 (yeast extract)	− 0.2381	− 0.1190	0.04111	− 2.90	8.39	0.020*
x 4 (Na2S2O3)	− 0.1427	− 0.0714	0.04111	− 1.74	3.01	0.121
x 5 (salt solution)	0.0794	0.0397	0.04111	0.97	0.93	0.362
x 6 (KH2PO4)	− 0.2547	− 0.1274	0.04111	− 3.10	9.60	0.015*
x 7 (MgSO4.7H2O)	0.3837	0.1918	0.04111	4.67	21.78	0.002**
x 8 (citric acid)	0.0332	0.0166	0.04111	0.40	0.16	0.697

Values of “Prob. > F” less than 0.0010, 0.0100, and 0.0500 indicate that model terms are extremely significant (***), highly significant (**), and significant (*), respectively