Enhanced production of diosgenin from Dioscorea zingiberensis in mixed culture solid state fermentation with Trichoderma reesei and Aspergillus fumigatus

Figures & data

Table 1. Central composite design (CCD) matrix for Tween 80, temperature and moisture content and the experimental responses.

Run	Tween 80 (%) x1 (X1)^a	Temperature (°C) x2, (X2)	Moisture content(%) x3, (X3)	Diosgenin yield (%)(T. reesei, y1)	Diosgenin yield (%)(A. fumigatus, y2)
1	−1 (0.50)	−1 (25.00)	1 (75.00)	59.51 ± 3.22	63.71 ± 4.26
2	1 (1.5)	−1 (25.00)	1 (75.00)	74.1 ± 6.71	74.86 ± 6.62
3	0 (1.00)	0 (30.00)	0 (70.00)	74.06 ± 8.35	71.82 ± 3.52
4	0 (1.00)	0 (30.00)	0 (70.00)	71.54 ± 5.61	71.73 ± 2.60
5	0 (1.00)	0 (30.00)	0 (70.00)	77.76 ± 5.40	70.39 ± 5.57
6	−1 (0.50)	−1 (25.00)	−1 (65.00)	34.82 ± 2.65	59.24 ± 6.91
7	1 (1.50)	1 (35.00)	−1 (65.00)	36.84 ± 2.44	65.19 ± 5.94
8	−1 (0.50)	1 (35.00)	−1 (65.00)	35.86 ± 3.79	61.15 ± 3.58
9	0 (1.00)	0 (30.00)	1.68 (78.41)	81.35 ± 6.25	65.62 ± 4.69
10	1 (1.50)	−1 (25.00)	−1 (65.00)	34.61 ± 3.69	66.01 ± 1.77
11	0 (1.00)	0 (30.00)	0 (70.00)	77.01 ± 1.43	71.08 ± 5.08
12	0 (1.00)	0 (30.00)	0 (70.00)	77.07 ± 1.88	68.69 ± 6.11
13	1 (1.50)	1 (35.00)	1 (75.00)	79.03 ± 3.52	70.66 ± 5.28
14	0 (1.00)	0 (30.00)	0 (70.00)	80.51 ± 2.64	69.42 ± 2.19
15	0 (1.00)	0 (30.00)	−1.68 (61.59)	36.14 ± 1.74	55.45 ± 4.24
16	−1 (0.50)	1 (35.00)	1 (75.00)	58.03 ± 3.36	69.17 ± 3.10
17	1.68 (1.84)	0 (30.00)	0 (70.00)	47.06 ± 4.01	73.43 ± 5.51
18	0 (1.00)	−1.68 (21.59)	0 (70.00)	69.30 ± 4.47	63.37 ± 4.62
19	−1.68 (0.16)	0 (30.00)	0 (70.00)	35.32 ± 2.08	65.54 ± 4.43
20	0 (1.00)	1.68 (38.41)	0 (70.00)	79.53 ± 6.20	64.63 ± 2.12

Note: ^ax_i = (X_i − X_c)/△X_i, where x_i and X_i are the coded and real values of an independent variable; X_c is the real value of an independent variable at the centre point; △X_i is the real value change of X_i.

Data in the table are mean ± standard deviations.

Table 2. The fit statistics of the two models.

Source	F	P	Source	F	P
Model 1	39.62	<0.0001^***	Model 2	17.89	<0.0001^***
x1	12.32	0.0056^**	x1	35.97	0.0001^**
x2	2.24	0.1654	x2	0.53	0.4822
x3	163.74	<0.0001^***	x3	51.45	<0.0001^***
x1x2	0.39	0.5484	x1x2	6.99	0.0246*
x2x3	8.10	0.0174*	x2x3	0.15	0.7043
x1x3	–	0.9886	x1x3	–	0.9718
$x_1^2$	141.73	<0.0001^***	$x_1^2$	–	0.9257
$x_2^2$	2.53	0.1430	$x_2^2$	18.92	0.0014^**
$x_3^2$	41.62	<0.0001^***	$x_3^2$	51.23	<0.0001^***
Lack of fit	2.85	0.1376	Lack of fit	2.41	0.178
R^2	0.9727		R^2	0.9415
Adj-R^2	0.9482		Adj-R^2	0.8889
CV%	7.10		CV%	2.47

Note: * <0.05 significant level; ** <0.01 significant level; ** <0.0001 significant level.

Figure 1. Effects of T:A ratio (a), inoculum level (b) and fermentation strategies (c) on diosgenin yield.

Figure 2. Profiles of α-rhamnase (○) and β-glucosidase (■) activities obtained from T. reesei (a), A. fumigatus (b) and mixed culture (c) SSF. Profiles of concentrations of diosgenin-diglucoside (□), diosgenin-glucoside-rhamnoside (•), diosgenin-glucoside (△) and diosgenin (▾) obtained from T. reesei (d), A. fumigatus (e) and mixed culture (f) SSF.