iBB

Responding to the recent interest of the yeast research community in non-Saccharomyces cerevisiae species of biotechnological relevance, the N.C.Yeastract was associated to YEASTRACT+, a curated repository of known regulatory associations between transcription factors (TFs) and target genes in yeasts. A recent Minireview published in FEMS Yeast Research aims to advertise the update of the existing information since the release of N.C.Yeastract in 2019, and to raise awareness in the community about its potential to help the day-to-day work on non-Saccharomyces species, exploring all the information and bioinformatics tools available in YEASTRACT +. Using simple and widely used examples, a guided exploitation is offered. The usage potentialities of the new CommunityYeastract platform by the yeast community are also discussed. The Minireview is coauthored by a BSRG-iBB team coordinated by Isabel Sá-Correia and including Cláudia P. Godinho, Margarida Palma, Miguel C. Teixeira and the PhD students Miguel Antunes and Marta N. Mota, in collaboration with INESC-ID colleagues.

There is a wide diversity of non-conventional yeast species, which often present distinctive metabolic properties and can therefore impart different flavours and aromas to beer. Because of this, brewers now regard non-conventional yeast species as a tool to differentiate their beers from other products in the market. In fact, some of these yeasts are already used to produce specific beer styles, such as lambics. A study recently published in Food Microbiology, coordinated by Dr. Margarida Palma and Prof. Isabel Sá-Correia and first authored by the BIOTECnico PhD student Nuno Melo, investigates how two non-conventional yeast species commonly found in wineries, Hanseniaspora guilliermondii and Hanseniaspora opuntiae, influence the volatile composition of beer. These two species, initially selected by a preliminary organoleptic evaluation, were found to modulate the aroma profile of beer, namely by increasing phenylethyl acetate concentration (‘rose’, ‘honey’ aroma). These findings highlight the importance of non-conventional yeasts in shaping the aroma profile of beer and suggest a role for Hanseniaspora spp. in improving it.

Agro-industrial residues rich in pectin are generated in high amounts worldwide from the sugar industry or the industrial processing of fruits and vegetables. A recent paper by BSRG-iBB researchers, published in the Journal of Fungi (special issue “Yeast Biorefineries” (edited by Isabel Sá-Correia and Naseem Gaur), describes the optimization of the performance of Rhodotorula strains envisaging the use of the major carbon sources present in Sugar Beet Pulp (SBP) hydrolysates. SBP valorization through the production of lipids and carotenoids by the oleaginous red yeasts examined, supported by complete catabolism of the major carbon sources present, looks promising for industrial implementation. The work was conducted by the PhD student of the IST PhD Programme in Biotechnology and Biosciences Luís C. Martins (FCT_DP AEM programme fellowship) under the supervision of Isabel Sá-Correia. This work was developed in the context of the ERA-NET-Industrial Biotechnology-2 project, “YEASTPEC-Engineering of the yeast Saccharomyces cerevisiae for bioconversion of pectin-containing agro-industrial side-streams”.

The non-conventional food spoiling yeast species Zygosaccharomyces bailii is remarkably tolerant to acetic acid, a highly important microbial inhibitory compound in Food Industry and Biotechnology. The study recently published in Scientific Reports, coordinated by Isabel Sá-Correia and Margarida Palma and first authored by the BIOTECnico PhD student Miguel Antunes, investigates the genomic transcription changes occurring during the early response of Z. bailii to acetic acid or copper stresses and uncovers the regulatory network activated under the bifunctional transcriptional factor ZbHaa1 control. This study provides valuable insights regarding Z. bailii adaptation mechanisms to acetic acid or copper stresses, ZbHaa1-dependent regulatory network, and the evolution of transcription factors and regulatory networks in pre- whole genome duplication (WGD) and post-WGD yeast species.