Browsing by Author "Olufemi, S. E."

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Bioethanol production from decaying oranges and pineapple juice using ethanol tolerant-yeast
(Sciencedomain International, 2023) Omoolorun, J. B.; Afolabi, F. T.; Olufemi, S. E.; Adeyemo, S. M.
Scientists across the globe ought to harness ways of getting alternative sources of energy which will be renewable, sustainable, efficient, eco-friendly, and cost effective because of the global energy crises owing to the cost of production, transportation and distribution of fossil fuel products. In Nigeria, decaying fruits always constitute a major environmental pollution during the harvesting season. This study screened, selected the best starter, and produced bioethanol from the juice obtained from decaying oranges and pineapple through the process of fermentation and distillation. Samples were collected from different locations within Ile-Ife and transported aseptically to the Laboratory. Microbiological and physicochemical assessment of the isolated strains were on yeast maintenance media. The cell biomass, pH, temperature, brix level, titratable acidity, specific gravity and ethanol yield were monitored during fermentation from day zero to day fourteen. Screening of the isolates obtained from a previous study was carried out to select the best starter for the production of bioethanol. S.cerevisae and K. marxianus and showed efficient physico-chemical attributes from the screening of the yeast isolates; a temperature of 30oC and pH 6 was the optimum for the growth of isolates tolerating 20% v/v absolute ethanol. Cultures were inoculated singly and in combination, S. cerevisiae gave the highest reduction in brix level from 2.2o at the onset and it reduced to 0.3o at the 21st day of fermentation while the least reduction was seen in K. marxianus. Mixed culture of S. cerevisiae and K. marxianus gave the highest reduction in brix level from 2.0o at the onset to 0.1o, pH reduced from 4.7- 3.3 while the cell biomass increased, and the temperature increased from 30oC to 34.5oC at the end of fermentation. Titratable acidity in the fermenting fruits juice increased from 0.23 to 1.76, the specific gravity reduced while the alcohol content increased from zero to 25.63 as the fermentation progressed and a reduction on day 21 (1.67) was observed. The use of decaying plant biomass or fruit waste can be a rich and cheaper source of substrate for different yeasts strains endogenous to the biomass for the production of environmental-friendly biofuel. This can also be employed as a waste management option and an alternative solution to environmental pollution and the global energy crises.
Selection of starter from decaying oranges and pineapple for bioethanol production
(Sciencedomain International, 2023) Omoolorun, J. B.; Afolabi, F. T.; Olufemi, S. E.; Adeyemo, S. M.
Screening of yeasts for bioethanol production is an important aspect of industrial microbiology and biotechnology. Optimal yeast nutrition also requires availability of nutrients allowing for growth and ethanol production and ability to withstand the increasing concentration of the medium during fermentation. This study seeks to use appropriate methods to isolate, characterize and identify yeasts isolates with essential attributes for bioethanol production. Microbiological and Physicochemical assessment of the isolated strains was carried out on yeast maintenance media for the determination of ethanol, temperature and salt tolerance ability, growth at different pH and temperature, chloramphenicol and nalidixic acid test, determination of killer toxins production capacity of yeast, nitrate and carbon assimilation and sugar fermentation tests were carried out to select the best starter for production. Fifteen yeasts were isolated belonging to the genera Saccharomyces, Candida, Rhodotorula, Kluvyreomyces, Trichosporon, Pichia. S. cerevisae and K. marxianus showed efficient physico chemical attributes. Proximate analysis of fruits juice showed a moisture content between 81.83 – 86.37%, crude protein 1.33 – 2.00%, Ash 0.73 – 0.83%, carbohydrate 11.87 – 15.67% and Ether 0.1 – 0.5%. The total sugar ranged from 1.83 – 13.17, equal mixture of oranges and pineapple juice showed a sugar content of 15 which reduced during fermentation while the alcohol content increased. Organisms were able to tolerate a percentage of 4-30% ethanol content, tolerating 15% sodium chloride which is an index of osmotolerance. At higher concentration, growth reduced, organisms produced catalase, reduced nitrate and showed a variation in utilization of different sugars. At the end of the screening, S. cerevisiae and K. marxianus showed the best attribute essential for bioethanol production and were chosen as starters. The ability of the selected yeast isolates to produce Killer toxins against E. coli showed a negative result. Antibiotic sensitivity test was carried out on the selected yeast isolates using chloramphenicol and nalidixic and the two organisms were resistant to the antibiotics tested. The ability of the organisms to grow in changing environmental conditions and ethanol tolerance are attributes essential for production while Saccharomyces cerevisiae showed the highest attribute followed by Kluveromyces marxinus. This study concluded that Saccharomyces cerevisiae can be employed as starter in the industry for the production of bioethanol and in the conversion of agricultural waste to wealth.