Improved production of Bacillus subtilis cholesterol oxidase by optimization of process parameters using response surface methodology

Journal of Genetic Engineering and Biotechnology

Table 2 Statistical analysis of the Plackett–Burman experimental results

Variable	Cholesterol degradation (%)				Cholesterol oxidase activity (U/OD₆₀₀)
Variable	Coefficient	Main effect	t-value	p-value	Coefficient	Main effect	t-value	p-value
C (g/l)	− 9.48333	− 18.966	− 7.47626	0.000676*	7.3075	14.6150	2.10046	0.089701
PP (g/l)	− 1.48333	− 2.9667	− 1.16940	0.294952	3.8158	7.6317	1.09682	0.322714
PN (g/l)	− 2.38333	− 4.7667	− 1.87892	0.119042	− 2.5058	− 5.0117	− 0.7202	0.503612
S (g/l)	− 1.51667	− 3.0333	− 1.19568	0.285431	5.1658	10.3317	1.48486	0.197710
M (g/l)	3.51667	7.0333	2.77239	0.039254*	− 5.2192	− 10.438	− 1.5001	0.193857
F (g/l)	1.11667	2.2333	0.88033	0.418975	− 3.7475	− 7.4950	− 1.0771	0.330606
V (ml/flask)	− 1.01667	− 2.0333	− 0.80150	0.459223	− 8.5275	− 17.055	− 2.4511	0.057856
I (%)	3.86667	7.7333	3.04832	0.028479*	− 0.3708	− 0.7417	− 0.1065	0.919258
pH	− 2.06667	− 4.1333	− 1.62927	0.164184	− 10.2258	− 20.451	− 2.9393	0.032283*

Abbreviations: C cholesterol concentration, PP potassium phosphate, PN potassium nitrate, S sodium chloride, M magnesium sulphate, F ferrous sulphate, V volume of the media, I inoculum size
^*Significant (p-value ≤ 0.05)