Kinetic Study on Fermentation of Biomass-derived Sugars by A Co-culture of Escherichia coli and Saccharomyces cerevisiae in Bioethanol Production

Departement of Chemical Engineering, Faculty of Engineering, Universitas Negeri Semarang, Kampus Sekaran, Gunungpati, Semarang, Indonesia

^* Corresponding author: Megawati@mail.unnes.ac.id

Abstract

This research's aim is to study the kinetics of co-fermentation of sugar cane bagasse hydrolysate using Escherichia coli and Saccharomyces cerevisiae. Before fermentation, the materials are pretreated with phosphoric acid 0.5% (w/w) at 190 °C for 5 minutes. Then they are hydrolysed using enzyme Cellic CTec3 15 FPU per g at 50 °C for a specified time. Fermentation is carried out at 37 °C, pH 6.3, with AM1BH as media and condition variation of: solids concentration, aeration or no aeration, and the addition of yeast extract. The empirical kinetic model, which is Gompertz model, could quantitatively describe the kinetics of co-fermentation of sugar cane hydrolysate well. The kinetics parameter values at solid concentration 10%, aeration 1.6 vvm, and yeast ratio 1% (w/v) is as follows: maximum ethanol concentration (C_Emax) = 3.9 g/L, maximum ethanol rate (R_Emax) = 0.18 g/L.h, and lag time (t_L) = 2 h.