Lipase production by Aspergillus niger using sheanut cake: An optimization study

Peer review under responsibility of Taibah University.

Figures & data

Table 1 Face-centred central composite design matrix with the experimental and predicted responses for lipase production.

Run	Tween-80 (% v/w)	(NH4)2SO4 (% w/w)	Na2HPO4 (% w/w)	Lipase activity (U/g)
				Experimental	Predicted
1	0.80	0.20	0.20	46.42	46.40
2	1.20	0.20	0.20	44.91	44.80
3	0.80	0.60	0.20	44.18	44.24
4	1.20	0.60	0.20	41.53	42.00
5	0.80	0.20	0.50	46.16	45.66
6	1.20	0.20	0.50	45.23	45.13
7	0.80	0.60	0.50	46.21	46.28
8	1.20	0.60	0.50	45.13	45.12
9	0.80	0.40	0.35	47.56	47.96
10	1.20	0.40	0.35	46.82	46.57
11	1.00	0.20	0.35	47.98	48.72
12	1.00	0.60	0.35	48.22	47.63
13	1.00	0.40	0.20	46.83	46.44
14	1.00	0.40	0.50	47.09	47.63
15	1.00	0.40	0.35	48.68	48.76
16	1.00	0.40	0.35	49.44	48.76
17	1.00	0.40	0.35	49.05	48.76
18	1.00	0.40	0.35	48.24	48.76
19	1.00	0.40	0.35	48.79	48.76
20	1.00	0.40	0.35	48.67	48.76

R² = 0.9607; Adj R² = 0.9253; CV = 1.15; Adeq precision = 17.802.

Fig. 1 Effects of different concentrations of Tween-80, olive oil and sucrose (0.2–1.2%) on lipase activity by A. niger using SNC as the main substrate.

Fig. 2 Effects of different concentrations of (NH₄)₂SO₄ and Na₂HPO₄ (0.1–0.6%) on lipase activity by A. niger using SNC as the main substrate.

Fig. 3 Effects of different concentrations of MgSO₄ (0.05–0.20%) on lipase activity by A. niger using SNC as the main substrate.

Table 2 ANOVA of the quadratic model developed for the optimization of lipase production.

Source	Sum of squares	F-Value	Probability > F	Significance^a
Model	70.5815	27.1580	<0.0001	Yes
A (Tween-80)	4.7748	16.5350	0.0023	Yes
B ((NH4)2SO4))	2.9485	10.2105	0.0096	Yes
C (Na2HPO4)	3.5403	12.2598	0.0057	Yes
A^2	6.1575	21.3234	0.0010	Yes
B^2	0.9455	3.2743	0.1005	No
C^2	8.1959	28.3822	0.0003	Yes
AB	0.2080	0.7203	0.4159	No
AC	0.5778	2.0009	0.1876	No
BC	3.8781	13.4298	0.0044	Yes
Lack of fit	2.0714	2.5376	0.1649	No

a p < 0.05 were considered to be significant.

Fig. 4 Plots showing the effects of Tween-80 and (NH₄)₂SO₄ at a fixed concentration of Na₂HPO₄ on lipase production by A. niger using SNC as the main substrate. (a) Response surface 3D and (b) contour plot (2D).

Fig. 5 Plots showing the effects of Tween-80 and Na₂HPO₄ at a fixed concentration of (NH₄)₂SO₄ on lipase production by A. niger using SNC as the main substrate. (a) Response surface 3D and (b) contour plot (2D).

Fig. 6 Plots showing the effects of Na₂HPO₄ and (NH₄)₂SO₄ at a fixed concentration of Tween-80 on lipase production by A. niger using SNC as the main substrate. (a) Response surface 3D and (b) contour plot (2D).

Table 3 Validation of the experimental model.

Run	Tween-80 (% v/w)	(NH4)2SO4 (% w/w)	Na2HPO4 (% w/w)	Lipase activity (U/g)
				Experimental	Predicted
1	1.00	0.35	0.40	49.37	48.81
2	0.95	0.45	0.35	48.89	48.68
4	1.00	0.45	0.40	48.77	48.65
5	0.95	0.35	0.35	49.21	48.93

Fig. 7 Reductions in tannin and saponin concentrations (%) and an increase of protein concentration (%) with time during the bioconversion of SNC for lipase production by A. niger.