iBB

We owe a great debt to yeasts for their contributions to humankind. In the Food Industry alone, yeasts play a central role in breadmaking, winemaking, brewing, and more. The fact that yeasts present such spectacular diversity constitutes an opportunity to use different, unused yeasts to obtain fermented goods with distinct properties and organoleptic profiles. In his interactive poster submission to the international conference World Microbe Forum, a joint initiative by the American Society for Microbiology (ASM) and Federation of European Microbiological Sciences (FEMS) taking place online from 20-24 June 2021, Nuno Bourbon-Melo talks about the role of non-conventional yeasts seldom used in brewing, specifically Hanseniaspora opuntiae and H. guilliermondii, to improve the aroma and flavour of beer. Learn more about it by clicking here. The work was performed at iBB – Institute for Bioengineering and Biosciences, Instituto Superior Técnico, ULisboa, and advised by Prof. Isabel Sá-Correia and Dr. Margarida Palma.

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.

Nuno Bourbon, PhD student from the BIOTECnico doctoral programme at iBB-BSRG, presented his work during the symposium on “Industrial and Food Microbiology” of the Congress of Microbiology and Biotechnology 2019 (Microbiotec’19), which was held between the 5th and 7th of December 2019 in Coimbra, Portugal. The presentation, entitled “Use of Hanseniaspora guilliermondii and Hanseniaspora opuntiae in co-fermentation with Saccharomyces cerevisiae to enhance the aromatic profile of craft beer”, focused on the potential of using two distinct Hanseniaspora yeast species to improve the organoleptic properties of beer. This work was carried out under the supervision of Prof. Isabel Sá-Correia (iBB-BSRG) and Dr. Margarida Palma (iBB-BSRG), in collaboration with Prof. Maria Rosário Bronze’s team (IBET and Faculty of Pharmacy, ULisboa, for the analysis of volatile compounds).

The role of the cell wall in yeast response and tolerance to stress is frequently neglected. A BSRG-iBB research paper just published in Scientific Reports, provides, for the first time, a comprehensive view of the alterations occurring at the cell wall in a yeast population adapting to sub-lethal stress induced by acetic acid. The results reveal changes to the cell wall polysaccharide composition and nanomechanical properties, as well as alterations in the transcript levels of key cell wall biosynthetic genes. This paper reinforces the notion that the adaptive yeast response to acetic acid involves coordinated alterations of the cell wall at the biophysical and molecular levels. The gathered knowledge is important for the design of superior industrial strains and for the efficient control of the deleterious activity of spoilage yeasts, particularly in the Food Industry. This research work is first-authored by the PhD student of the PhD programme in Biotechnology and Biosciences Ricardo Ribeiro (FCT_DP AEM fellowship), performed under the supervision of Isabel Sá-Correia. This collaborative study with Fábio Fernandes (BSIRG-iBB) and Mário S. Rodrigues and his team (BioISI, Faculty of Sciences, ULisboa), is also coauthored by Cláudia Godinho (posdoc researcher) and the PhD student Nuno Bourbon-Melo (FCT_DP BIOTECnico) from the BSRG-iBB team.

Nuno Bourbon, PhD student from the BIOTECnico doctoral programme at iBB-BSRG, was awarded 1st place in the “GENERAL” category of the competition “Science Communication in Microbiology”, promoted by the Portuguese Society of Microbiology (SPM) to commemorate the International Microorganism Day 2019. The competition seeks to encourage and facilitate the communication of relevant microbiology topics to the general public in a concise and attractive fashion by asking contestants to summarise the topic in an image which, if selected, is to be published in an eBook accompanied by a short explanatory description. His entry, entitled “Microbiology of beer”, provides an overview of the main yeast and bacterium species used in brewing and how different volatile compounds arising from their metabolism can impact the flavour and aroma of this alcoholic beverage.