SUSTAINABLE UTILIZATION OF FRUIT WASTES FOR PRODUCTION OF BIOETHANOL USING THERMOTOLERANT SACCHAROMYCES CEREVISIAE YEAST ISOLATED FROM COMMON FRUITS OF BANGLADESH

Bioethanol is one of the most important biofuel due to its positive impact on the environment. However, its economic production is dependent primarily on the raw materials used and the fermentation potentiality of the microorganisms. Therefore, this study was aimed to screen for thermotolerant Saccharomyces cerevisiae yeast isolates from common fruits of Bangladesh and produce bioethanol from decaying fruit wastes. Nine different fruits were collected and subjected for anaerobic growth. Colonies similar to S. cerevisiae yeast were isolated based on cultural (colony shape, size, color, elevation, surface edge, consistency), morphological (bud, cell shape) and biochemical characteristics (carbohydrate fermentation). Molecular confirmation was done using S. cerevisiae RSP5-C allele specific primer. Six isolates were confirmed as S. cerevisiae based on cultural, morphological, biochemical and molecular characteristics studied. From the four isolates that showed the growth capacity at a higher (41 degrees C) temperature than optimum (30 0C), SC-Gr, the isolate from grape, showed the most active growth at 41 degrees C and used to produce bioethanol from decaying fruits like banana, papaya, apple and grape. The significantly highest amount of bioethanol concentration (7.92 %) was obtained from the grape waste at 37 degrees C, at pH 5 after 48 hrs of the fermentation period and the lowest amount of bioethanol (2.37 %) was obtained from decaying banana at 45 degrees C and pH 5.0 after 72 hrs of fermentation period. This study suggested that decaying fruits could be better utilized in the industry of renewable fuel energy using thermotolerant yeast isolate from grapes.