Bioethanol fermentation from sugarcane bagasse using ragi tape

The purpose of the research was to use sugarcane bagasse as a fermentation substrate for bioethanol production and to determine the effect of yeast types from traditional inoculum for tapay making (ragi) on ethanol yield. Sugarcane bagasse was composed of lignocellulosic materials and collected from a sugar factory in Yogyakarta. Yeasts from ragi were used to break down the cellulose containing in sugarcane bagasse. Dilute alkali hydrolysis of sugarcane bagasse was performed to obtain sugarcane bagasse cellulosic hydrolysate. This hydrolysate was supplemented with nutrient formulations to prepare the fermentation medium to the yeast activity. Saccharomyces cerevisieae pombe SPJ, strain YRT-01, strain YRT-02 and YRT-03 (isolated from Ragi) were used in fermentations carried out using batch culture system in Erlenmeyer flasks incubated in a rotator shaker (100 rpm for 72 h) at room temperature. Yeast activity was determined based on their growth (OD660 nm) and reducing sugar concentration (A540 nm – 575nm) with xylose or glucose as standard. The ethanol concentration was determined by Conway method. The results showed that bagasse hidrolyzate contains (6.9 to 8.0) g · L−1 of xylose and glucose. The highest ethanol concentration was obtained 1.387 % by strain YRT-03 during 4 d incubation, indicating that yeast strain YRT-03 was the promising yeast for sugarcane bagasse fermentation to produce ethanol under temperature at 32 °C and pH 5.5. This strain resembles to Saccharomyces cerevisiae pombe.