Optimizing Ethanol Production by Thermotolerant Kluyveromyces marxianus CCT 7735 in a Mixture of Sugarcane Bagasse and Ricotta Whey

The simultaneous saccharification and fermentation (SSF) process is a promising strategy to obtain ethanol from cellulosic biomass. In this study, sugarcane bagasse was supplemented with ricotta whey to increase the sugar, vitamin, and trace metal concentrations in the fermentation medium. The optimum conditions for SSF ethanol production from a mixture of sugarcane bagasse and ricotta whey produced by Kluyveromyces marxianus CCT 7735 were evaluated considering five factors: cellulase concentration, cellulosic biomass concentration, pH, temperature, and agitation. The highest ethanol yield was 49.65 g/L with a cellulosic biomass of 80 g/L, pH value of 5.05, agitation at 65 rpm and temperature of 39.2°C. The results demonstrated that a mixture of the cellulosic residue of sugarcane bagasse and ricotta whey is promising for ethanol production because the ethanol yield in the mixture was higher than that in single substrate of sugarcane bagasse.