Production of β-Glucosidase from a Newly Isolated Aspergillus Species Using Response Surface Methodology

Table 1

Process variables used in the central composite design (𝐾=3) with actual factor levels corresponding to coded factor levels.

Factor	code^a	Actual factor level at coded factor levels of
		−2	−1	0	1	2
%cellobiose	𝑋1	0.500	1.125	1.750	2.375	3.000
%yeast extract	𝑋2	0.050	0.275	0.500	0.725	0.950
% (NH4)2SO4	𝑋3	0.6	1.1	1.6	2.1	2.6
pH	𝑋4	3.0	4.5	6.0	7.5	9.0

^aCode level limits are based on preliminary investigations and also to reflect what was done in practice.
𝑋₁ = (%cellobiose-1.75)/0.625, 𝑋₂ = (%yeast extract-0.5)/0.225, 𝑋₃ = (% (NH₄)₂SO₄ -1.6)/0.5, and 𝑋₄ = (pH-6.0)/1.5.
^bLevels based on the central composite design.