SUMATHI, SPISE SATISH AMBADAS2016-06-242016-06-242011http://krishikosh.egranth.ac.in/handle/1/67901Ethanol is quantitatively and economically the world’s premier biotechnological commodity. Ethanol can be produced from any fermentable carbohydrates by yeasts. A long term goal of the brewing industry is to identify yeast strains with increased tolerance to the stresses experienced during the brewing process. A combination of high temperature, ethanol and sugar tolerance is clearly desirable characteristics in fermentation processes. Until 1990s, classical tests based on morphology, biochemical and sexual reproduction characteristics were used for wine yeast identification. Such methods only allowed discrimination between species and they were laborious, time consuming and imprecise. In the last decade, the application of several molecular techniques has generated a large number of studies concerning ecology and biodiversity of indigenous Saccharomyces cerevisiae strains. The present investigation is carried out with the objective of isolating ethanologenic yeasts from different sources and location followed by screening for diversity on basis of alcohol production and functional characteristics using cultural and molecular methods. Twenty samples were obtained from different sources and pure isolates were identified as yeast cultures based on their morphological characters, cultural characters, carbohydrate assimilation profile and alcohol producing ability. All isolates had alcohol producing ability but maximum alcohol production was observed with standard yeast culture Saccharomyces cerevisiae MTCC-172 (67.77 g l-1) followed by isolate APY-4 (67.53 g l-1) and AMY-2 (67.50 g l-1) while isolate AMY-7 produced the least (30 g l-1). Twenty yeast isolates and standard yeast culture Saccharomyces cerevisiae MTCC- 172 were screened for ethanol tolerance, thermo tolerance, sugar tolerance and osmotolerance. It was found that isolates exhibited high diversity for tolerance and were grouped according to it. Based on these results it was observed that isolates APY-4, AMY- 2, AMY-9 and standard culture Saccharomyces cerevisiae - MTCC-172 were best among all isolates. These four pure cultures were tested for their alcohol producing ability at 40°C by inoculating them in fermentation medium containing 20% sugar. Four yeast cultures fermented sugar and produced alcohol at 40°C and 20% sugar concentration. Isolate AMY- 2 showed superior capacity for alcohol production and sugar conversion efficiency (SCE) while the standard culture Saccharomyces cerevisiae MTCC-172 exhibited better alcohol production and sugar conversion efficiency (SCE) at 40°C and 20% sugar concentration. Genomic DNA of 21 pure cultures of Saccharomyces cerevisiae were analyzed by RAPD technique using fifteen different primers and a dendrogram was constructed. Only isolates AMY-7 and APY-2 formed separate single element groups in dendrogram. The dendrogram analysis was compared with analysis formed from assimilation profiles, cultural characteristics, morphological characteristics and functional characteristics (sugar conversion efficiency, thermotolerance, osmotolerance, ethanol tolerance and sugar tolerance) which revealed great biodiversity among the twenty one pure Saccharomyces cerevisiae cultures. Based on the present study it is established that the important functional diversity found for ethanol tolerance, thermotolerance, sugar tolerance and osmotolerance indicate that the use of wider range of yeast isolates could be outlined and further developed for valorization. These results can be applied for optimization of alcohol production, brewery and baking industries as well in tropical countries such as India. Strain biodiversity represents a fundamental source of specific and also potential rare characteristics, which contributes to increase the economics of fermentation. This natural biodiversity represents an essential source for selection of strains possessing desirable characteristics. The use of molecular method like RAPD helps in elucidation of genetic diversity among the isolated yeast strains thereby establishing their evolutionary relationships. This will enable researchers in designing novel strains carrying all desirable characteristicsenfungi, yeasts, alcohols, fermentation, sugar, tolerance, productivity, rapd, concentrates, biological developmentThesis