Isolation and characterization of yeast strains for bio-ethanol production

Yeast strains are commonly associated with sugar rich environments. Ethanol production by yeasts has been extensively studied, the aimof this study was to isolate and characterize yeast to produce ethanol. The investigation was carried out to isolate and characterization of yeast strains from their natural habitats and to screen them for ethanol tolerance and ethanol production. Out of 40 microbial cultures 10 were identified as Saccharomyces strains at Genus level by colony morphology, biochemical characteristics and cell morphological characters. An attempt has been made to check the viability of yeast cells under different concentrations of ethanol. Saccharomyces species were screened for the ability to tolerate different ethanol concentrations from 0-18%. Growth in different ethanol concentrations varied from one strain to another. Yeast strains showed tolerance level from 7-16%. Even though some strains had tolerance at 16% but the growth was less. Yeast from molasses and grapes showed highest tolerance among 10 isolates up to 16. The study was aimed at determining the genetic variability and efficiency among yeast strains. Out of twenty five primers, eight primers were shown polymorphism and successful in amplifying DNA in the sample. Analysis was employed to characterize yeast isolates. Ten Saccharomyces strains were subjected to ADH specific primer analysis using eight primers. Cluster diagram was divided into 2 major cluster and 3 sub cluster, two major cluster showing 30% dissimilarity. There was correlation between ethanol tolerance and genetic relatedness shown by ADH specific primer analysis. Key words: Yeast, Bio-Ethanol, ADH-Specific primers.