Enhancement of feather degrading keratinase of Streptomyces swerraensis KN23, applying mutagenesis and statistical optimization to improve keratinase activity

Table 1 Experimental factors and level of minimum and maximum range for statistical screening using Plackett–Burman factorial design (PBFD)

Factors	Independent Factor	Unit	Range Level
Factors	Independent Factor	Unit	Minimum (− 1)	Maximum (+ 1)
X1	Incubation time	Hours	24	72
X2	pH	-	5	9
X3	Sucrose (carbon source)	% (w/v)	0.5	2.5
X4	Yeast extract (nitrogen source)	% (w/v)	0.5	2.5

ISSN: 1471-2180