Raw agro-industrial orange peel waste as a low cost effective inducer for alkaline polygalacturonase production from Bacillus licheniformis SHG10

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Table 4 Real-coded values of ten independent variables and regression analysis for PGase optimization by PBD

Variable	Low level	High level	Main effect	Β-coefficient	P-value	t-value	% confidence
Variable	-1	+1	Main effect	Β-coefficient	P-value	t-value	% confidence
Orange peel waste (% w/v)	0.5	2.0	0.513	0.2565	0.020839*	2.796274	97.92
NaNO₃ (% w/v)	0.1	0.4	-0.083	-0.0415	0.661675	-0.45242	33.84
MgSO₄ (% w/v)	0.1	0.4	0.261	0.1305	0.188555	1.422666	81.15
CaCl₂ (% w/v)	0.1	0.4	0.255	0.1275	0.197956	1.389961	80.21
FeSO₄ (% w/v)	0.1	0.4	0.179	0.0895	0.354709	0.975698	63.53
KNO3 (% w/v)	0.1	0.4	0.037	0.0185	0.844651	0.201681	15.45
pH	6.0	9.0	1.501	0.7505	1.85E-05*	8.181689	99.99
Inoculum size (% v/v)	1.0	5.0	0.215	0.1075	0.271314	1.171928	72.87
Incubation temperature°C	37.0	50.0	-0.811	-0.4055	0.00167*	-4.42062	99.83
Incubation time (hrs)	24.0	60.0	-0.245	-0.1225	0.214517	-1.33545	78.55

*Significant P-value <0.05 & R² = 0.93 & Adjusted R² = 0.83 and P -value for the model = 0.000869.