Isolation and characterization of Saccharomyces cerevisiae for the production of ethanol from organic sources

Abstract

Microbial production of ethanol is a very popular concept in respect of alleviating energy demand nowadays. In this regard, two fermenting strains of Saccharomyces cerevisiae were isolated from date-juice and grapes and grown in YEPD medium. They are characterized for alcoholic fermentation using sugarcane molasses and organic kitchen wastes media. The fermentation of molasses was optimized with respect to pH and sugar concentration. Results revealed a temperature of 30C, pH 6.0 and 6.5% sugar concentration as optimum for fermentation. Stress tolerance tests showed date-juice strain is highly thermo-, pH-, osmo- and ethanol-tolerant. Conway method for estimating percentage of ethanol was employed. Under optimized conditions, S. cerevisiae from date-juice produced 7.75% of ethanol in molasses. Kitchen-wastes resulted in 7.3% ethanol after 48 hours of fermentation by the same yeast cells.