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Metabolic and genetic engineering of a Saccharomyces cerevisiae industrial strain for transport and co-fermentation of xylose and cellobiose to inprove the ethanol production process from sugarcane bagasse

Grant number: 18/25898-3
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): August 01, 2019
Effective date (End): July 31, 2021
Field of knowledge:Biological Sciences - Biochemistry
Principal Investigator:Roberto Do Nascimento Silva
Grantee:Karoline Maria Vieira Nogueira
Home Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

One of the challenges to the economic viability of ethanol produced from lignocellulosic biomass (2G ethanol) is in the fermentation stage. Saccharomyces cerevisiae, is widely used in Brazilian plants for the production of 1G ethanol. However, for this yeast be employed with success in producing large volume of 2G ethanol is necessary to expand the use of different carbon sources, including pentoses (such as xylose ), present in the lignocellulosic biomass. Besides this yeast not being able to ferment pentoses, in S. cerevisiae, glucose repression caused by the consumption of high concentration of this sugar during the fermentation process results in the inhibition of other metabolic pathways involved in the use of different carbon sources. One of the promising mechanisms for circumventing glucose repression and providing the simultaneous use of different carbon sources is the consumption of cellobiose by the yeast. However, this yeast is not able to metabolize xylose and cellobiose, besides not having the genes coding for specific transporters of these sugars in its genome. In order to build strains to transport and metabolism of D-xylose and cellobiose, this project will use the S. cerevisiae MEC 1133 as background to introduce genes encoding the Tr_69957 transporter from Trichoderma reesei and an intracellular ²-glucosidase from Neurospora crassa. The strain S. cerevisiae MEC 1133 was engineered for xylose metabolism and developed using the S. cerevisiae strain PE-2 - widely used in Brazilian ethanol plants - as background. With this, we intend to obtain a higher yield strain of ethanol production obtained from sugarcane bagasse hydrolyzate. (AU)