d(GC) - Association of Biotechnology and Pharmacy
d(GC) - Association of Biotechnology and Pharmacy
d(GC) - Association of Biotechnology and Pharmacy
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Current Trends in <strong>Biotechnology</strong> <strong>and</strong> <strong>Pharmacy</strong><br />
Vol. 6 (2) 241-254 April 2012, ISSN 0973-8916 (Print), 2230-7303 (Online)<br />
<strong>of</strong> the mutual interactions between the test<br />
variables. The F value <strong>and</strong> the corresponding P<br />
values, along with the coefficient estimate, are<br />
given in Table 2. The smaller the magnitude <strong>of</strong><br />
the P, the more significant is the corresponding<br />
coefficient. Values <strong>of</strong> P less than 0.050 indicate<br />
the model terms to be significant. The coefficient<br />
estimates <strong>and</strong> the corresponding P values<br />
suggests that, among the test variables used in<br />
the study, B, C, A 2 , B 2 , AB, AC <strong>and</strong> BC (where A<br />
= glucose, B = yeast extract, C = MgSO 4 ) are<br />
significant model terms. B, A 2 , B 2 <strong>and</strong> AB (P <<br />
0.0001) have the largest effect on GSH<br />
production. Other intearctions were found to be<br />
insignificant.<br />
The corresponding second-order response<br />
model for Eq. (7) that was found after analysis<br />
for the regression was:<br />
GSH (mg/L) = 139.13 – (0.70 x glucose) +<br />
(13.38 x yeast extract) – (2.29 x magnesium<br />
sulphate) – (24.94 x glucose 2 ) – (27.50 x yeast<br />
extract 2 ) + (0.71 x magnesium sulphate 2 ) + (11.40<br />
x glucose x yeast extract) + (5.47 x glucose x<br />
249<br />
magnesium sulphate) – (5.12 x yeast extract x<br />
magnesium sulphate) (7)<br />
The fit <strong>of</strong> the model was also expressed by<br />
the coefficient <strong>of</strong> regression (r 2 ), which was found<br />
to be 0.996, indicating that 99.6 % <strong>of</strong> the<br />
confidence level <strong>of</strong> the model to predict the<br />
response (GSH yield). The “Pred R-Squared” <strong>of</strong><br />
0.975 is in reasonable agreement with the “Adj<br />
R-Squared” <strong>of</strong> 0.992. “Adeq Precision” measures<br />
the signal to noise ratio. A ratio greater than 4 is<br />
desirable. Here, the ratio <strong>of</strong> 47.095 indicates an<br />
adequate signal. The special features <strong>of</strong> the RSM<br />
tool, “contour plot generation” <strong>and</strong> “point<br />
prediction” were also studied to find optimum<br />
value <strong>of</strong> the combination <strong>of</strong> the three media<br />
constitutes for the maximum production <strong>of</strong> GSH.<br />
These predicted values were experimentally<br />
verified. Table 3 documents the predicted <strong>and</strong><br />
experimental yields <strong>of</strong> GSH by various media<br />
combination. It was observed that medium<br />
containing (%), glucose 5.67, yeast extract, 7.13<br />
<strong>and</strong> magnesium sulphate, 0.66 yielded maximum<br />
(148.45 mg/L) GSH.<br />
Table 2. Analysis <strong>of</strong> variance (ANOVA) for the experimental results <strong>of</strong> the central<br />
composite design (Quadratic Model)<br />
Factor a Estimate Sum <strong>of</strong> St<strong>and</strong>ard DF b F value p<br />
Coefficient squares Error<br />
Intercept 139.13 61.28 1.25 1 270.75 < 0.0001<br />
A -0.70 6.71 0.82 1 0.73 0.4159<br />
B 13.38 2445.59 0.82 1 264.87 < 0.0001<br />
C -2.29 71.52 0.82 1 7.75 0.0213<br />
A 2 -24.94 8953.57 0.80 1 969.70 < 0.0001<br />
B 2 -27.50 10888.97 0.80 1 1179.31 < 0.0001<br />
C 2 0.71 7.18 0.80 1 0.78 0.4009<br />
AB 11.40 1039.22 1.07 1 112.55 < 0.0001<br />
AC 5.47 238.93 1.07 1 25.88 0.0007<br />
BC -5.12 209.51 1.07 1 22.69 0.0010<br />
a A = glucose, B = yeast extract, C = MgSO4<br />
b Degree <strong>of</strong> freedom, p < 0.05 (models are significant), R 2 = 0.99<br />
Enhanced Production <strong>of</strong> Glutathione