Saccharification and Single Step Fermentation of Cassava Peel by Mixed Culture of Saccharomycopsis fibuligera NCIM 3161 and Zymomonas mobilis MTCC 92

Abstract

The main objective of this study was to utilize the cassava peel by saccharification and single step fermentation (SSF) by mixed culture of Saccharomycopsis fibuligera NCIM 3161 and Zymomonas mobilis MTCC 92. Single step fermentation was performed in conical flasks with various concentrations of cassava peel (30, 50, 70 and 90 g/L), pH (3.5, 4.5 and 5.5), temperature (37, 47 and 57° C), reaction time (72, 720 and 168 h), inoculum size (5, 10 and 15 % v/v) and agitation speed (50, 100 and 150 rpm). Cell growth was identified by measuring optical density at 660 nm. The total reducing sugars were determined by centrifuging at 5000 rpm for 10 min by 3,5-dinitrosalicylic acid method. Starch concentration was estimated by anthrone method. Ethanol concentration was determined by acid dichromate method. The optimum process conditions were substrate concentration of 70 g/L, pH of 4.5, temperature of 37° C, reaction time of 120 h, inoculum size of 10 % (v/v) and agitation speed of 100 rpm. Under these conditions, the highest ethanol concentration of 26.46 g/L was obtained for cassava peel (93.75 % of theoretical yield).