Statistical Analysis and Optimization of Operation Conditions of Lipase Production by Rhizopus Arrhizus

In this study, in order to optimize the production of lipase from Rhizopus oryzae in the liquid culture medium, the design of the experiment was carried out by using the response surface methodology to the central operating state by the design expert 7.0.0 software. Fermentation was performed by selecting the parameters including the mass ratio of carbon source to nitrogen source, the agitation speed, and the initial pH in the range of variation (0.2-1), (100-250), (5-8) respectively. The experiments were carried out by using the olive oil stimulus as a carbon source at 32 ° C. The activity amount of the lipase enzyme was measured by titration of the free fatty acids (NaOH 0.1 molar as a titrant) and the mass of biomass was calculated by the gravity method. (Responses: Enzyme activity and the bulk of mass both produced after 48 and 96 hours). The statistical analysis of the experimental data was obtained from measuring the activity of the lipase enzyme, indicates that the models presented with 95% confidence for enzyme activity after 48 hours of cultivation have the desired effect of increasing the agitation and the alkalinity of the culture. It also shows that It is desirable to increase the agitation of the stirrer and reduce the mass ratio of the carbon source to the nitrogen source for the activity of the lipase enzyme after 96 hours of cultivation. Optimum fermentation conditions of lipase enzyme, respectively, the ratio of carbon source to nitrogen source 0.4, agitation 100 (rpm) and initial pH 8, with the production of the highest activity of the extracellular lipase enzyme (2.48, 4.89)(U/ml) was obtained after 48 and 96 h cultivation which shows a more efficient process than previous similar researches.