Optimization of lactic acid production from different substrates using Rhizopus oryzae

Abstract

A vital chemical compound, lactic acid, is one of the raw materials for production of bioplastic. As the demand for bioplastic goes on increasing day by day, the demand for lactic acid also increases. Production of lactic acid by bioprocess at low cost is the current demand of time. In this work, lactic acid produced from different substrates by concurrent saccharification and fermentation by Rhizopus oryzae was studied. Optimization of various process parameters comprising a concentration of substrate, time, and temperature was also carried out. The maximum average yield of lactic acid 0.80 g lactic acid/g of dry mass was obtained from corn compared with sweet potato and beetroot. The maximum productivity of lactic acid was discovered to be 1 g/h L at temperature 30˚C and time interval of 24 h. The optimized 100 g/L substrate concentration was shown the highest lactic acid yield. The experimental data were evaluated using the Michaelis- Menten Equation and Gompertz model which provides a good fit for experimental results with the determination coefficient (R2) being 0.92 and 0.96 respectively.