OPTIMIZATION STUDIES OF YEAST FEED FOR ENHANCED GROWTH FOR ETHANOL PRODUCTION BY SHAKE FLASK METHOD

Abstract

Yeasts are the industrially used microorganisms to provide the best possible combination of characteristics for the biological reactions with the given substrates. Yeast nutrition refers to how cells feed, translocate water and essential in-organic and organic nutrients from the ecosystem. Saccharomyces cerevisiae of bakery origin (strain SS) and soil origin wild strain (strain S6) were cultivated on nutrient agar and were activated on Saboraud's dextrose agar and Czepkdox agar, potato dextrose agar and malt extract agar by three subsequent inoculations for the maximum growth. Test strains $5 and $6 were optimized for their growth requirements in malt extract broth as initial medium; pH was maintained at 5.0 and incubated at 37°C for 72 hours, 110 rpm, 1.0 ml inocula size. Growth studies were under taken in three replicates after every 4 hours till 96 hours. Number of nutritional requirements were provided at the optimized concentrations in the form of yeast media 5 and 6 respectively and finally the growth was observed at 600 nm. The test strains grown on growth media (5 and 6) were also subjected for their tolerance to various chemical agents at the respective concentrations (ml v/v). Present study revealed the higher growth rate of S. cerevisiae strains $5 on Gm5 as compared to the strain S6 on Gm6 containing vitamins and amino acids as growth promoting factors at 110 rpm, pH 4.0, 0.5 and 1 ml. inocula size after 72 hours incubation by shake flask method which indicates that strain S5 is the best candidate for ethanol production.