Improved Production of Sublancin 168 Biosynthesized by Bacillus subtilis 168 Using Chemometric Methodology and Statistical Experimental Designs

Table 2

Variables and test levels for Plackett-Burman experiment.

Number	Variables	Code levels		Estimate	t-value	value	Significance
		−1	1
	Peptone (g/L)	8	12	2.33	1.01	0.3851
	Corn powder (g/L)	20	30	27.20	11.83	0.0013	*
	Starch (g/L)	10	20	3.19	1.39	0.2594
	Soybean meal (g/L)	24	36	21.09	9.17	0.0027	*
	KH2PO4 (g/L)	3	6	3.21	1.39	0.2575
	(NH4)2SO4 (g/L)	3	6	−0.96	−0.42	0.7038
	Incubation temperature (°C)	28	34	11.11	4.83	0.0169	*
	Initial pH	6.5	8.5	−1.91	−0.83	0.0466
	Incubation time (h)	28	40	0.38	0.17	0.8786
	Inoculum size (%)	1	3	−2.34	−1.01	0.3834

 * indicates model terms are significant.