A Sequential Statistical Approach towards an Optimized Production of a Broad Spectrum Bacteriocin Substance from a Soil Bacterium Bacillus sp. YAS 1 Strain
Table 4
(a) BBD with coded levels of three independent variables and experimental versus predicted BAC YAS 1 levels. (b) Real-coded values of independent variables and regression analysis for BAC YAS 1 optimization by BBD.
(a)
Trial number
(AU/mL CFS)*
Exp.a
Pred.b
1
−1
−1
0
220
238.75
2
1
−1
0
400
366.25
3
−1
1
0
320
353.75
4
1
1
0
370
351.25
5
−1
0
−1
300
313.75
6
1
0
−1
210
211.25
7
−1
0
1
280
278.75
8
1
0
1
360
346.25
9
0
−1
−1
220
187.50
10
0
1
−1
200
180.00
11
0
−1
1
240
260.00
12
0
1
1
200
232.50
13
0
0
0
430
443.33
14
0
0
0
450
443.33
15
0
0
0
450
443.33
Experimental values and bpredicted values. : incubation time, : agitation speed, and : yeast extract. *AU/mL sample: arbitrary units as a measure for bacteriocin activity = diameter of inhibition zone in mm. 1000/volume of CFS in L. *CFS: cell-free supernatant.
(b)
Variable
Low level
Middle level
High level
Model term
Main effect
-coefficient
-value
value
% confidence
−1
0
+1
Incubation time (, hrs)
24
48
72
50.00
25
1.65144
0.159558
84.0
Agitation speed (, rpm)
80
200
320
62.50
31.25
0.07506
0.943073
5.69
Yeast extract (, g/L)
2
5
8
−17.50
−8.75
1.12598
0.311295
68.87
−43.34
−21.67
−0.88395
0.417196
58.28
−188.34
−94.17
−3.84178
0.012102*
98.79*
−268.34
−134.17
−5.47369
0.002773*
99.72*
−65.00
−32.50
−1.38007
0.226083
77.39
85.00
42.50
1.80470
0.130962
86.90
−10.00
−5.00
−0.21232
0.840243
15.98
Significant value <0.05; ; adjusted ; value for the model = 0.01.
