A Sequential Statistical Approach towards an Optimized Production of a Broad Spectrum Bacteriocin Substance from a Soil Bacterium Bacillus sp. YAS 1 Strain
Table 3
(a) PBD with coded levels of nine independent variables and experimental versus predicted levels of BAC YAS 1. (b) Real-coded values of independent variables and regression analysis for BAC YAS 1 optimization by PBD.
(a)
Trial number
(AU/mL CFS)*
Exp.a
Pred.b
1
−1
−1
1
1
1
−1
1
1
−1
290
296.67
2
−1
−1
−1
−1
−1
−1
−1
−1
−1
250
248.33
3
−1
1
1
1
−1
1
1
−1
1
220
218.33
4
−1
1
1
−1
1
−1
−1
−1
1
340
341.67
5
1
−1
−1
−1
1
1
1
−1
1
380
386.67
6
1
1
−1
1
1
−1
1
−1
−1
420
413.33
7
1
−1
1
−1
−1
−1
1
1
1
360
353.33
8
−1
−1
−1
1
1
1
−1
1
1
390
383.33
9
1
−1
1
1
−1
1
−1
−1
−1
320
321.67
10
1
1
−1
1
−1
−1
−1
1
1
460
466.67
11
1
1
1
−1
1
1
−1
1
−1
400
398.33
12
−1
1
−1
−1
−1
1
1
1
−1
200
201.67
Experimental values and bpredicted values [: incubation time, : glucose, : pH, : incubation temperature, : agitation speed, : glycerol, : starch, : inoculum size, 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)
Independent variable
Low level
High level
Main effect
-coefficient
value
-value
% confidence
−1
+1
Incubation time
24
48
108.34
54.17
0.004*
15.76482
99.6*
Glucose , w/v%
1
2
8.33
4.167
0.349
1.212678
65.1
pH
6.5
7.5
−28.33
−14.167
0.0541
−4.12311
94.59
Incubation temperature , °C
28
30
28.33
14.167
0.0541
4.123106
94.59
Agitation speed
120
200
68.33
34.167
0.0099*
9.943961
99.01*
Glycerol
0
1
−35.00
−17.5
0.0363*
−5.09325
96.37*
Starch
0
1
−48.33
−24.167
0.0196*
−7.03353
98.04*
Inoculum size , v/v%
10
12
28.33
14.167
0.054095
4.123106
94.59
Yeast extract
3
5
45.00
22.500
0.0225*
6.548462
97.75*
Significant value <0.05; ; adjusted ; and value for the model = 0.017.
