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Institute for Bioengineering and Biosciences
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Genome-wide Search for Candidate Genes for Yeast Robustness Improvement Against Formic Acid

Genome-wide Search for Candidate Genes for Yeast Robustness Improvement Against Formic Acid | iBB | Scoop.it

Synthetic pathway engineering for robustness improvement of industrial strains envisaging their use in lignocellulosic biorefineries requires the understanding of the complex molecular mechanisms underlying Saccharomyces cerevisiae tolerance to inhibitors present in  hydrolysates. This study, recently published in Biotechnology for Biofuels, was led by Isabel Sá-Correia and part of Silvia F. Henriques PhD thesis in Biotechnology and Biosciences and also co-authored by Nuno P. Mira. The paper reports the identification, at a genome-wide scale, of genes whose expression confers protection or susceptibility to formic acid. This chemogenomic analysis allowed the identification of 172 determinants of tolerance and 41 determinants of susceptibility, among them HAA1, encoding the main transcriptional regulator of yeast transcriptome reprograming in response to acetic acid, and genes of the Haa1-regulon. TRK1, encoding the high-affinity potassium transporter and genes encoding positive regulators of Trk1 activity were surprisingly found among the genes that when deleted lead to increased tolerance to formic acid. It was hypothesized that Trk1 facilitates formic acid uptake into the yeast cell and demonstrated that at a saturating K+ concentrations, trk1Δ mutant is more tolerant than the parental strain. The list of genes resulting from this study provides potentially valuable information to guide improvement programs for the development of more robust strains against formic acid.

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Improvement of Yeast Tolerance to Acetic Acid Through Haa1 Transcription Factor Engineering

Improvement of Yeast Tolerance to Acetic Acid Through Haa1 Transcription Factor Engineering | iBB | Scoop.it

Saccharomyces cerevisiae tolerance to acetic acid is an important phenotype in Industrial Biotechnology since it may contribute to fermentation inhibition/arrest during winemaking and is an important inhibitor in lignocellulosic hydrolysates used for bioethanol production. In the framework of the Era-Net Industrial Biotechnology research project INTACT-“Integral Engineering of Acetic Acid Tolerance in Yeast”, funded in Portugal by FCT, the engineering of the transcription factor Haa1 was attempted envisaging the construction of more robust strains. Haa1 is the major orchestrator of yeast response to acetic acid and a tolerance determinant. This study, led at iBB by Prof. Isabel Sá-Correia and having as first co-author Silvia Henriques, a PhD student of the IST Program in Biotechnology and Biosciences, identified the beneficial S135F mutation (an exchange of serine to phenylalanine, at position 135). This mutated Haa1 leads to increased transcriptional activation under acetic acid stress of Haa1-target genes and higher tolerance to this short-chain weak acid.

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Sílvia Henriques Defends PhD Thesis in Biotechnology and Biosciences

Sílvia Henriques Defends PhD Thesis in Biotechnology and Biosciences | iBB | Scoop.it
Sílvia Catarina Filipe Henriques will be defending her Ph D thesis in Biotechnology and Biosciences at Instituto Superior Técnico, monday the 6th april 2017 (11:30 H, room PA3). During the last years, and under the supervision of Isabel Sá-Correira from BSRG-IBB, Sílvia focused her efforts on the study of the effect of weak acids on yeast. The title of Sílvia's thesis is ”Towards the Improvement of Tolerance to Acetic Acid and Formic Acids in Yeast: Identification of Candidate Genes and Engineering of the Haa1 Transcription Factor”.
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