Isolation of Saccharomyces Cerevisiae from Pineapple and Orange and Study of Metal’s Effectiveness on Ethanol Production

In view of the anticipated shortage of the traditional supplies of fossil fuels, there is a great deal of interest in the production of ethanol as an alternative biofuel in recent years. The main objective of this research work was to isolate and characterize stress tolerant, high potential ethanol producing yeast strains from various fruit peel. Two yeast isolates from pineapple (Pa) and orange (Or) have been isolated, characterized on the basis of morphological and physic-chemical characters and optimized on ethanol producing capability using sugarcane molasses as substrate. Ethanol production percentage was estimated by Conway method. Isolates were thermotolerant, pH tolerant, ethanol tolerant as well as osmotolerant. They were resistant to Chloramphenicol (30 μg/disc) and Nalidixic acid (30 μg/disc). The isolates showed no killer toxin activity against E. coli. The highest production capacity of the yeasts was found to be 7.39% and 5.02% for Pa and Or, respectively, at pH 5.0, 30 °C temperature in media with an initial reducing sugar concentration of 6.5% for Pa and 5.5% for Or (shaking). Addition of metal ions increased the rate of ethanol production highest to 10.61% by KH(2)PO(4). This study revealed that indigenous yeast isolates could be used to benefit the fuel demand and industrial alcohol industries.