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Title: Bioethanol production from renewable resources - central role of non-conventional yeasts

Speaker: Maria José Leandro

Affiliation: Helena Santos Lab, ITQB NOVA

Abstract: The concept of circular bioeconomy has become an awareness-raising topic by the European Union that is promoting actions focused on the sustainable production of renewable resources and their conversion in biobased products and bioenergy.

The yeast Saccharomyces cerevisiae is still the privileged choice for most industrial bioprocesses, due to its specific characteristics as ability to ferment under strictly anaerobic conditions, resistance to low pH values, high ethanol tolerance and insensitivity to bacteriophage infections, a major problem in industries that rely on bacteria for bioprocessing.  However this yeast has also some natural metabolic drawbacks, such as inability to use sugars as lactose, and a strong glucophilic behavior, as glucose is preferably consumed before all the other sugars, which are only consumed after glucose exhaustion.

The study of non-conventional yeasts with diverse advantageous characteristics, such as preference for other sugars over glucose or tolerance to high temperatures, is fundamental for improving industrial bioprocesses, as it can provide valuable genetic tools to further improve S. cerevisiae metabolic performance.

In this context, two examples of the importance of non-conventional yeasts in the conversion of renewable resources into bioethanol will be presented: the direct use of native non-conventional yeasts as cell factories to ferment industrial dairy wastewaters; and the use of genetic material from non-conventional yeasts to construct novel recombinant engineered S. cerevisiae strains to ferment lignocellulosic hydrolysates.