Identification and statistical optimization of fermentation conditions for a newly isolated extracellular cholesterol oxidase-producing Streptomyces cavourensis strain NEAE-42

Table 7 Central composite design representing the response of cholesterol oxidase production by Streptomyces cavourensis strain NEAE-42 as influenced by initial pH (X₁), cholesterol (X₂) and ammonium sulphate (X₃) along with the predicted cholesterol oxidase production and residuals and the levels of variables with actual factor levels corresponding to coded factor levels

Std	Run	Type	Variables			Cholesterol oxidase activity (U/mL)		Residuals
			X₁	X₂	X₃	Experimental	Predicted	Residuals
14	1	Axial	0	0	1.68	6.362	5.970	0.392
11	2	Axial	0	−1.68	0	18.184	17.893	0.290
7	3	Factorial	−1	1	1	10.612	10.674	−0.062
3	4	Factorial	−1	1	−1	16.506	15.551	0.955
4	5	Factorial	1	1	−1	15.367	14.300	1.067
19	6	Center	0	0	0	20.403	20.365	0.038
5	7	Factorial	−1	−1	1	13.655	14.060	−0.405
2	8	Factorial	1	−1	−1	13.630	12.906	0.724
12	9	Axial	0	1.68	0	14.992	16.218	−1.226
9	10	Axial	−1.68	0	0	15.492	15.476	0.016
10	11	Axial	1.68	0	0	11.401	12.353	−0.951
1	12	Factorial	−1	−1	−1	14.431	14.408	0.023
6	13	Factorial	1	−1	1	11.303	11.596	−0.293
17	14	Center	0	0	0	20.348	20.365	−0.017
18	15	Center	0	0	0	20.424	20.365	0.059
20	16	Center	0	0	0	20.279	20.365	−0.086
16	17	Center	0	0	0	20.521	20.365	0.156
13	18	Axial	0	0	−1.68	9.845	11.172	−1.327
8	19	Factorial	1	1	1	9.101	8.462	0.639
15	20	Center	0	0	0	20.376	20.365	0.011
Level		pH	Cholesterol (g/L)			Ammonium sulphate (g/L)
−1.68		6	1			5
−1		7	2			6
0		8	3			8
1		9	4			9
1.68		10	5			10

ISSN: 1471-2180