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Doctoral Thesis
DOI
https://doi.org/10.11606/T.87.2012.tde-04062012-112721
Document
Author
Full name
Julio Cezar Araujo do Espírito Santo
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2012
Supervisor
Committee
Stambuk, Boris Juan Carlos Ugarte (President)
Basso, Luiz Carlos
Fernandes, Patricia Machado Bueno
Gombert, Andreas Karoly
Schenberg, Ana Clara Guerrini
Title in Portuguese
Aperfeiçoamento da fermentação de sacarose através da modificação da expressão dos genes SUC2 e AGT1 em linhagens diploides de Saccharomyces cerevisiae.
Keywords in Portuguese
Saccharomyces
Expressão gênica
Fermentação alcoólica
Regulação gênica
Sacarose
Abstract in Portuguese
Atualmente, as cepas de S. cerevisiae utilizadas na produção industrial de álcool combustível no Brasil são leveduras diplóides que metabolizam a sacarose através da sua hidrolise extracelular pela invertase periplasmática, seguida pelo transporte para o interior da célula das moléculas de glicose e frutose formadas, e posterior metabolização pela glicólise. Neste trabalho, utilizando técnicas de engenharia genética e posteriores cruzamentos, foram desenvolvidas cepas diplóides de S. cerevisiae capazes de consumir este açúcar por meio da sua captação direta pelo transportador codificado pelo gene AGT1, e hidrólise intracelular pela invertase citoplasmática codificada por uma versão modificada do gene SUC2. Estas modificações permitiram alcançar um rendimento 10% maior na produção de etanol, além de aumentar a velocidade de consumo da sacarose e diminuir a quantidade de açúcares residuais ao final do processo. Estes resultados abrem novos horizontes para tornar a produção de etanol no Brasil mais eficiente.
Title in English
Improvement of sucrose fermentation by modifying the expression of SUC2 and AGT1 genes in diploid Saccharomyces cerevisiae strains.
Keywords in English
Saccharomyces
Alcoholic fermentation
Gene expression
Gene regulation
Sucrose
Abstract in English
Currently, the S. cerevisiae strains used in industrial production of fuel alcohol in Brazil are diploid yeasts that of metabolize sucrose through its extracellular hydrolysis by the periplasmic invertase, followed by the transport of the formed glucose and fructose into the cells, and further metabolism through glycolysis. In this study, utilizing genetic engineering techniques and further crosses, diploid strains of S. cerevisiae were developed that are able to consume this sugar through its direct uptake by the transporter encoded by the AGT1 gene, and intracellular hydrolysis by the cytoplasmic invertase encoded by a modified version of the SUC2 gene. These modifications allowed achieving a 10% higher yield in the production of ethanol, besides increasing the sucrose consumption rate and decreasing the amount of residual sugars at the end of the process. These results open new horizons to turn ethanol production in Brazil more efficient.
 
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Publishing Date
2012-07-06
 
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