Production of Proteolytic Enzymes by a Keratin-Degrading Aspergillus niger

Table 4

Main effects and interaction analysis for keratinase production by A. niger growing on feather meal.

Factors	Effect keratinase	Standard error	t value	P value
Medium	0.702720	0.063294	11.10241	0.001566*
Feather meal (L)	−0.045272	0.089646	−0.50501	0.648314
Feather meal (Q)	−0.369430	0.100496	−3.67606	0.034853*
pH (L)	0.959379	0.089646	10.70186	0.001744*
pH (Q)	0.387574	0.100496	3.85660	0.030803*
Feather meal × pH	−0.130000	0.126590	−1.02694	0.380013

𝑅²=0.93.
*Significant factors, 𝑃<0.05.