Novel Effective Yeast Strains and Their Performance in High Gravity and Very High Gravity Ethanol Fermentations from Sweet Sorghum Juice

Yeasts were isolated from four potential sources, sweet sorghum juice, sugar cane grapes and rambutan. The 27 yeast isolates tested for their ethanol tolerance (15% v/v of ethanol) fermentation performance in a synthetic production medium (200 g/L total sugar). Only five isolates, SCJ04KKU, SCJ07KKU, SCJ09KKU, SCJ14KKU SSJ01KKU could tolerate 15% produce at levels higher than 55 g/L. efficiency juice under high gravity (HG, 200 240 sugar) very (VHG, 280 conditions the was tested. Saccharomyces cerevisiae NP01 S. ATCC4132 used as reference strains. results showed that isolate gave highest all conditions. Ethanol concentration (PE), yield (YP/S) productivity (QP) values 98.89 g/L, 0.50 1.18 g/L·h, respectively, with consumption (SC) 98.96% HG condition sugar. Under sugar, PE, YP/S QP 118.12 0.51 1.41 SC 95.79%. These 82.29 0.34 0.98 85.59% VHG condition. Addition urea into significantly shortened time, resulting increased values. Based on molecular taxonomic analysis using sequence D1/D2 domain ITS1 ITS2 regions, is cerevisiae, whereas SCJ09KKU are Pichia caribbica.