KINETIC PARAMETER ESTIMATION FOR GLUCONIC ACID PRODUCTION USING ASPERGILLUS NIGER

Abstract

D-Gluconic acid is a simple dehydrogenation product of D-glucose which is widely used in the food, pharmaceutical and chemical industries. Its market is now over 60,000 Mg per annum and still growing. Production of gluconic acid using several routes such as chemical, electrochemical, enzyme bioreactor, free and immobilized cells of either gluconobacter oxydans, penicillium chrysomgeneum or Aspergillus niger have been extensively studied. In the present work, the bioconversion of glucose to gluconic acid under submerged conditions using mycelia of Aspergillus niger has been studied, it has potential for better yield of gluconic acid. The aim of this work has been to estimate the kinetic parameter of gluconic acid production. Also to study the effect of glucose concentration and temperature on production of gluconic acid production. For this experiment has been carried out at 5 glucose concentration ranging from 40 kg/m3to 200 kg/m3 at different temperatures. The kinetic models used are logistic equation for growth of biomass, Luedeking-Piret equation for gluconic acid formation and equation used by Sikula., et al 2007 for substrate consumption. Parameters of these equations are estimated using curve fitting utilizing M S Excel and Sigmaplot 10 softwares. Using estimated parameters simulated results for rate of reaction are obtained. Effect of variation in temperature and initial glucose concentration on various parameters of model is studied and also their effect on rate and yield of the reaction system. Further the optimum conditions for the production of gluconic acid are obtained, namely temperatures of 30°C and 160 kg/m3 of the initial concentration of the substrate.