Statistical Optimization of Aspartase Production from Aeromonas media NFB-5 in a Stirred Tank Reactor

Optimization of process parameters for the production of aspartase by Aeromonas media NFB-5 was carried out at a laboratory scale bioreactor using response surface methodology (RSM). The effect of aeration (0.30–1.70, vvm), agitation (130–270, rpm) and incubation time (7–40, h) was studied on aspartase activity and biomass yield. The statistical assessment of the data was carried out by Fisher's statistical test for analysis of variance (ANOVA). The significance of each coefficient for aspartase production and biomass yield was determined by Fisher's F-test and P-values. Coefficient of determination of aspartase activity (R²=0.9995) and biomass yield (R²= 0.9973) depicted by the model was 99.95% and 99.73%, respectively of the total variation. At the same time, a relatively lower value of the coefficient of variation for aspartase activity (cv = 1.10%) and biomass yield (cv = 2.37%) indicated reliability of the conducted experiments. The model predicted optimal levels of agitation (250 rpm), aeration (1.30 vvm) and incubation time (24 h). Aspartase activity (171.42 U/g wet wt) and biomass yield (0.987 OD₆₀₀₅) obtained under optimal conditions were in good agreement with the values predicted by statistical method.