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Resumo(s)
Bioethanol production from lignocellulosic materials is only viable if the process of converting the biomass to ethanol is efficient. One of the conditions that affect this efficiency is the resistance of the fermentative microorganisms to the toxic compounds that are formed during the necessary lignocellulosic materials pre-treatment.
The current work analyzed the behavior of Saccharomyces cerevisiae growing on a medium containing inhibitory compounds to the fermentation, compounds that are present on an industrial lignocellulosic hydrolysate. The effect of the elimination of non-essential genes on the cells fermentative metabolism was studied. The non-essential genes eliminated were genes involved in the regulation and metabolism of nitrogen (TOR1, GLN3, PRO1, PUT4, ARO4), in the cell’s response to oxidative stress (SOD2, ZWF1, ADH6), osmotic stress (HOG1, TPS1, NTH1, HSP12) and general stress (HSP26), on the regulation of the intracellular pH (RIM101, VMA1), and in apoptosis (AIF1, FIS1). The results obtained from these procedures were indicative that some of these genes mutations are relevant for determining the fermentation efficiency.
The behavior of four selected mutant strains was further characterized. Besides the determination of glucose concentration, extracellular pH and CFU at the beginning of stationary phase and glucose exhaustion, for these four chosen strains, the ethanol concentration and the influx and efflux of protons through the plasmatic membrane were also collected.
Descrição
Mestrado em Engenharia de Sistemas Bioenergéticos - Instituto Superior de Agronomia
Palavras-chave
lignocellulosic bioethanol lignocellulosic hydrolysates fermentation yeast bioetanol lenhocelulósico hidrolisados lenhocelulósicos fermentação levedura