Rhizomucor miehei lipase supported on chitosan-graphene oxide beads for the production of geraniol propionate

Abstract

The biotechnological route to manufacturing geraniol propionate may present a feasible solution to drawbacks associated with the production of such ester by the chemical synthesis or extraction from plants. The use of such technique can be advantageous considering the ever increasing demands for such products while reducing waste production and simplifying the manufacturing process. The properties and morphology of the developed Rhizomucor miehei lipase (RML) immobilized onto activated chitosan-graphene oxide (CS/GO) support were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The morphological evaluations strongly indicated successful covalent attachment of the RML on the support. It was evident from the thermogram of TGA that 13.5% of RML was successfully immobilized onto the CS/GO matrix. The approach of response surface methodology (RSM) employing the Box-Behnken design (BBD) based on four parameters (incubation time, temperature, substrate molar ratio, and enzyme loading) were used to seek the optimized experimental conditions for the RML-CS/GO catalyzed synthesis of geraniol propionate. The study illustrated that the predicted and actual responses were well correlated, suggesting adequacy of the generated model for predicting the yield of the ester, as well as the factor of reaction time being most impacting in the RML-CS/GO catalyzed synthesis of geraniol propionate. Under optimized conditions, the highest yield of geraniol propionate (49.46%) was obtained at 17.98 h, 37.67 °C, 100.70 rpm, and molar ratio of acid:alcohol of 1:3.28 in the solvent free esterification of propionic acid and geraniol. The investigation demonstrated that the developed RML-CS/GO was a promising alternative to overcome drawbacks associated with solvent assisted enzymatic reactions. Therefore, the RML-CS/GO biocatalysts developed here appear to be a promising substitute and yet environmentally practical biocatalyst for the production of geraniol propionate.