Table 2.

Experimental variables at different levels used for production of Melanin

Factors	Variable	Units	Experimental values
			Low (−1)	High (+1)
1	pH		5	9
2	Temperature	°C	40	50
3	Inoculum volume	CFU/Ml	0.5	1.5
4	Incubation time	Days	3	7
5	Substrate	g	3	7
6	Moisture content	%	10	25
7	Sodium dihydrogen phosphate	g	10	14
8	Potassium dihydrogen phosphate	g	1	3
9	Magnesium sulphate	g	0.1	0.5
10	Calcium chloride	g	0.5	1.0
11	Ferrous sulphate	g	0.1	1