Ethanol production with different immobilization methods

More than 80% of the world's energy consumption comes from fossil fuels, which leads to environmental problems and climate change. The decline in fossil fuel resources, leading to global warming, climate change and other problems, has led developed countries towards renewable energy sources such as biofuels. Biofuels are energy sources derived from biomass and have low environmental impact. Bioethanol is a biofuel that is widely used especially in the transportation sector and stands out with its high efficiency. In this thesis study, immobilized Saccharomyces cerevisiae (S. cerevisiae) yeast cells were utilized for ethanol production. Increasing bioethanol productivity is very important in terms of time, cost and energy. For this purpose, immobilization, medium optimization were performed in this thesis. First of all, PCS2 (support material containing 5% soybean meal, 5% yeast extract, 5% bovine albumin) and Hex materials were selected as the best materials for ethanol production among 4 different PCS (Plastic Composite Support) and 4 different 3D materials (Hex, grid, X, W) for immobilization. Dried white mulberry was used as carbon source and its extraction was carried out under optimum conditions to increase the yield. The best material selection for immobilization and medium optimization steps were performed in synthetic medium (45 g/L glucose, 45 g/L fructose, 1 g/L sucrose) of dried white mulberry hydrolysate. Different amounts of 7 different nutrient components were added to a synthetic medium, and the Plackett-Burman designs was used to formulate 10 different nutrient combinations. These formulations were applied using both PCS materials and 3D materials, fermentations were conducted and for maximum ethanol production in PCS materials, the optimum nutrient composition was determined to be 20 g/L peptone and 0.5 g/L KH2PO4 and 20 g/L peptone, 3 g/L KH2PO4, 2 g/L (NH4)2SO4 for Hex materials. Validation fermentation was performed with both white mulberry dried hydrolysate and synthetic medium. In the last step, continuous ethanol fermentation was carried out with dried white mulberry hydrolysate according to the results of validation fermentation. Additionally, at the end of each fermentation, sugar consumption, ethanol production, ethanol yield, specific growth rate, doubling time and kinetic parameters of the continuous system were calculated.