Table 2.

Box–Behnken design with actual and coded levels of variables and actual values of responses

Run numbers	Nitrogen source (%)	pH	Time (h)	Biomass yield (g dry mass/L)	Transglutaminase activity (U/mL)
1	1	5.5	48	12.02 ± 0.36	2.812 ± 0.50
2	4	5.5	48	17.25 ± 0.52	1.354 ± 0.24
3	1	6.5	48	14.93 ± 0.45	2.332 ± 0.42
4	4	6.5	48	22.75 ± 0.68	5.085 ± 0.91
5	1	6.0	24	11.55 ± 0.35	1.739 ± 0.31
6	4	6.0	24	14.26 ± 0.43	0.819 ± 0.15
7	1	6.0	72	11.06 ± 0.33	3.114 ± 0.56
8	4	6.0	72	18.92 ± 0.57	1.288 ± 0.23
9	2	5.5	24	15.62 ± 0.47	2.476 ± 0.44
10	2	6.5	24	14.36 ± 0.43	1.350 ± 0.24
11	2	5.5	72	16.03 ± 0.48	2.687 ± 0.48
12	2	6.5	72	16.58 ± 0.50	2.829 ± 0.50
13	2	6.0	48	18.71 ± 0.56	4.595 ± 0.82
14	2	6.0	48	17.22 ± 0.52	4.348 ± 0.78
15	2	6.0	48	18.42 ± 0.55	4.561 ± 0.81