Optimization and partial purification of beta-galactosidase production by Aspergillus niger isolated from Brazilian soils using soybean residue

AMB Express

Table 2 Results of β-galactosidase activity (U/mL), according to the 2³ factorial design with centered face and three repetitions at the central point central

Run orders	Coded levels			β-Galactosidaseactivity (U/mL)^a
Run orders	X ₁	X ₂	X ₃	β-Galactosidaseactivity (U/mL)^a
1	− 1	− 1	− 1	19.64
2	1	− 1	− 1	19.02
3	− 1	1	− 1	7.07
4	1	1	− 1	8.83
5	− 1	− 1	1	10.06
6	1	− 1	1	0.03
7	− 1	1	1	0.00
8	1	1	1	1.12
9	0	0	0	23.4
10	0	0	0	24.64
11	0	0	0	22.60

Data: (X₁) speed agitation, (X₂) temperature and (X₃) pH on β-galactosidase production
^aOne unit (U) of β-galactosidase activity was defined as the amount of the enzyme catalyzing the release of 1 µmol of o-nitrophenol per min at 410 nm (Nagy et al. 2001)