Table 2.

Box–Behnken experimental design for GABA production in B. subtilis ATCC 6051

Run	Factor A	Factor B	Factor C	Titer of GABA
	Peptone (g/L)	Potato starch (g/L)	Sodium l-glutamate (g/L)	Observed value (g/L)	Predicted value (g/L)
1	40	20	5	13.12 ± 0.22	13.38
2	40	5	20	16.73 ± 1.01	16.47
3	20	12.5	5	10.50 ± 0.37	9.76
4	40	12.5	12.5	15.59 ± 1.10	16.10
5	40	12.5	12.5	16.48 ± 0.73	16.10
6	60	12.5	20	16.53 ± 1.06	17.27
7	40	12.5	12.5	15.28 ± 1.06	16.10
8	20	20	12.5	11.71 ± 1.01	12.19
9	40	5	5	11.13 ± 0.53	11.29
10	60	20	12.5	19.27 ± 1.75	18.69
11	20	5	12.5	13.68 ± 0.88	14.26
12	60	12.5	5	18.18 ± 1.79	18.50
13	40	12.5	12.5	16.45 ± 1.11	16.10
14	60	5	12.5	19.96 ± 1.26	19.48
15	40	20	20	11.69 ± 0.38	11.53
16	40	12.5	12.5	16.68 ± 1.29	16.10
17	20	12.5	20	14.61 ± 0.31	14.29