Table 2.

Central composite design (CCD) design of RSM using four independent variables showing actual and predicted values of keratinase activity by Bacillus sp. Nnolim-K1.

Run	Independent Variable				Response: Keratinase Activity (U/mL)
	A: Xylose (%)	B: pH	C: Feather (%)	D: Inoculum (%)	Experimental	Predicted
1	0.6(0)	7(+1)	1.25(0)	2(0)	1181.82	1180.66
2	0.6(0)	6(0)	1.25(0)	2(0)	1280.91	1232.85
3	0.8(+1)	5(−1)	1(−1)	1(−1)	1320.91	1313.14
4	0.6(0)	6(0)	1.25(0)	1(−1)	1217.27	1209.21
5	0.8(+1)	5(−1)	1(−1)	3(+1)	1589.09	1460.64
6	0.6(0)	5(−1)	1.25(0)	2(0)	1367.27	1344.30
7	0.4(−1)	6(0)	1.25(0)	2(0)	1219.09	1162.38
8	0.8(+1)	5(−1)	1.5(+1)	3(+1)	1332.73	1249.40
9	0.8(+1)	6(0)	1.25(0)	2(0)	1146.36	1178.94
10	0.8(+1)	7(+1)	1(−1)	3(+1)	1217.27	1297.00
11	0.8(+1)	7(+1)	1.5(+1)	3(+1)	1145.45	1085.76
12	0.6(0)	6(0)	1.25(0)	2(0)	1369.09	1232.85
13	0.4(−1)	5(−1)	1(−1)	1(−1)	1253.64	1296.57
14	0.6(0)	6(0)	1.25(0)	2(0)	1318.18	1232.85
15	0.8(+1)	7(+1)	1(−1)	1(−1)	1130.91	1149.50
16	0.6(0)	6(0)	1.25(0)	2(0)	1164.54	1232.85
17	0.4(−1)	7(+1)	1(−1)	1(−1)	1146.36	1132.93
18	0.4(−1)	5(−1)	1.5(+1)	3(+1)	1213.64	1232.83
19	0.8(+1)	7(+1)	1.5(+1)	1(−1)	1145.45	1138.72
20	0.4(−1)	7(+1)	1(−1)	3(+1)	1369.09	1280.43
21	0.6(0)	6(0)	1.5(+1)	2(0)	1253.64	1218.34
22	0.6(0)	6(0)	1(−1)	2(0)	1318.18	1329.35
23	0.6(0)	6(0)	1.25(0)	2(0)	1312.73	1232.85
24	0.4(−1)	5(−1)	1.5(+1)	1(−1)	1346.36	1285.79
25	0.4(−1)	5(−1)	1(−1)	3(+1)	1358.18	1444.07
26	0.6(0)	6(0)	1.25(0)	2(0)	1070.91	1232.85
27	0.4(−1)	7(+1)	1.5(+1)	1(−1)	1146.36	1122.15
28	0.8(+1)	5(−1)	1.5(+1)	1(−1)	1147.27	1302.35
29	0.6(0)	6(0)	1.25(0)	3(+1)	1080.91	1256.49
30	0.4(−1)	7(+1)	1.5(+1)	3(+1)	973.64	1069.20