Optimization of glucoamylase production by Mucor indicus, Mucor hiemalis, and Rhizopus oryzae through solid state fermentation

Objective: Glucoamylase is a hydrolyzing enzyme with several industrial applications. Glucoamylase was produced via a solid state fermentation by three naturally occurring zygomycetes fungi of Mucor indicus, Mucor hiemalis, and Rhizopus oryzae on wheat bran. Methods: The effects of cultivation temperature, medium moisture content, and cultivation time on the enzyme production were investigated. Experiments were designed with an orthogonal central composite design on the three variables using response surface methodology (RSM). Results: For glucoamylase production, the optimum temperature and medium moisture content for the three fungi were 26.6 degrees C and 71.8%, respectively. The optimum cultivation time for M. hiemalis and R. oryzae was 33.1 h, while it was 66.8 h for M. indicus. At optimum conditions, glucoamylase production by M. indicus, M. hiemalis, and R. oryzae was respectively 255.3, 272.3, and 1545.3 U per g dry substrate. Conclusion: R. oryzae is a suitable candidate for industrial production of glucoamylase.