MERRY CHRISTMAS and HAPPY 2022 !!!

Mercè Sunyer has successfully presented her PhD thesis

Last 19th November 2021, our PhD student Mercè Sunyer has presented in the Faculty of Oenology her thesis "Protective effects of bioactive compounds against fermentation-associated stresses in Saccharomyces cerevisiae". Directors: M. Jesús Torija and Gemma Beltran. She has got the maximum qualification. Congratulations, new Doctor !!

Xiaolin Zhu has successfully presented her PhD Thesis

Last 3rd November 2021, our PhD student Xiaolin Zhu has presented online from China her thesis "Microbiological non-GMO approaches for the reduction of ethanol in wines". Directors: Gemma Beltran, Yurena Navarro and Albert Mas. She has got the maximum qualification. Congratulations, new Doctor !!

Online BE (Wine Biotechnology) Group meeting, 15th October 2021

Last Friday 15th October we have celebrated the monthly online meeting of Wine Biotechnology Research Group.

The last results of different projects have been discussed and our colleague Xiaolin Zhu (predoctoral researcher) has presented an assay of her PhD defence that will be next 3rd November.

RedBAL (Spanish LAB network) online meeting with communication of Candela Ruiz de Villa

RedBAL (Spanish Lactic Acid Bacteria network) has celebrated its 14th annual meeting, 8-10 September 2021. The program and book of abstracts is available here.

Our PhD student Candela Ruiz de Villa has successfully presented her work on screening of yeast strains in relation to malolactic fermentation.

New article - a review - on the microbial interactions in alcoholic beverages

Microbial interactions in alcoholic beverages (Review)

Rafael Torres-Guardado, Braulio Esteve-Zarzoso, Cristina Reguant, Albert Bordons

International Microbiology  2021  https://doi.org/10.1007/s10123-021-00200-1

    This article is a review that examines the different types of interactions between the microorganisms involved in the fermentation processes of alcoholic beverages produced all over the world from cereals or fruit juices. 

    The alcoholic fermentation converting sugars into ethanol is usually carried out by yeasts, mainly Saccharomyces cerevisiae, which can grow directly using fruit sugars (wine, cider, and others), or on previously hydrolyzed starch of cereals (beers and others). Some of these beverages, or the worts from cereals, can be distilled to obtain spirits. Besides S. cerevisiae, all alcoholic beverages can contain other microorganisms, mostly lactic acid bacteria and other yeasts —the non-Saccharomyces yeasts—. 

    The interactions between all these microorganisms are very diverse and complex, as in any natural occurring ecosystem. The positive or negative effects of these interactions on the organoleptic qualities of the final product have been also revised. Focusing mainly on the alcoholic beverages produced by spontaneous fermentations, this paper reviews the interactions between the different yeasts and lactic acid bacteria in wine, cider, beer and in spirits such as tequila, mezcal and cachaça.

NEW Position Offer

POSITION OFFER : one Trainee predoctoral researcher in our group, with Lactic acid bacteria research team. Click here.

Online BE (Wine Biotechnology) Group meeting, 9th July 2021

 Last Friday 9th July we have celebrated the monthly online meeting of Wine Biotechnology Research Group.

The last results of different projects have been discussed and our colleague Sandra Martín (predoctoral researcher) has presented her work carried out on design of microbial consortia for improving stability and bioactivity of wines.

Two new articles on the effect of non-Saccharomyces on Oenococcus oeni

1) Torulaspora delbrueckii promotes malolactic fermentation in high polyphenolic red wines

Aitor Balmaseda, Nicolas Rozès, Albert Bordons, Cristina Reguant *

LWT Food Sci Technol 2021, 148, 111777: https://doi.org/10.1016/j.lwt.2021.111777

The interactions of Torulaspora delbrueckii and O. oeni in wines from grapes with different degrees of maturity were studied. The results showed higher total polyphenolic index (TPI) values in T. delbrueckii wines. Overall, the use of T. delbrueckii resulted in better MLF performances.

 

2) Simulated lees of different yeast species modify the performance of malolactic fermentation by Oenococcus oeni in wine-like medium

Aitor Balmaseda, Nicolas Rozès, Albert Bordons, Cristina Reguant *

Food Microbiology 2021, 99, 103839: https://doi.org/10.1016/j.fm.2021.103839

This is the first study of MLF with different O. oeni strains in the presence of S. cerevisiae and non-Saccharomyces yeast lees. Non-Saccharomyces lees, especially from some strains of Torulaspora delbrueckii, showed higher compatibility with some O. oeni strains, with a shorter MLF and a maintained bacterial cell viability. 

 

Online BE (Wine Biotechnology) Group meeting, 4th June 2021

Last Friday 4th June we have celebrated the monthly online meeting of Wine Biotechnology Research Group.

The last results of different projects have been discussed and our colleague Candela Ruiz de Villa Sardón (predoctoral researcher) has presented her work carried out on screening of alcoholic and malolactic fermentations with non-Saccharomyces and Oenococcus oeni, in synthetic wine and in wine rosé.

Online BE (Wine Biotechnology) Group meeting, 7th May 2021

Last Friday 7th May we have celebrated an online meeting of Wine Biotechnology Research Group.

The last results of different projects have been discussed and our colleague Aitor Balmaseda (predoctoral researcher) has presented the work carried out during his research stage at the University of Burgundy in Dijon, on the effects of Torulaspora delbrueckii on nitrogen metabolism of Oenococcus oeni.

New article on ethanol reduction by multistarter yeast inoculum

Effect of a multistarter yeast inoculum on ethanol reduction and population dynamics in wine fermentation

Xiaolin Zhu, Maria-Jesús Torija, Albert Mas, Gemma Beltran*, Yurena Navarro

Foods 2021, 10, 623. https://doi.org/10.3390/foods10030623

Microbiological strategies are currently being considered as methods for reducing the ethanol content of wine. In this study, fermentations started with a multistarter of three non-Saccharomyces yeasts (Metschnikowia pulcherrima (Mp), Torulaspora delbrueckii (Td) and Zygosaccharomyces bailii (Zb)) at different inoculum concentrations, and S. cerevisiae (Sc) was inoculated into fermentations at 0 h (coinoculation), 48 h or 72 h (sequential fermentations).

The analysis of the microbial populations showed Td as the dominant non-Saccharomyces yeast in all fermentations, and Mp the minority yeast. Sc was able to grow in all fermentations where it was involved, being the dominant yeast at the end of fermentation. 

We obtained a significant ethanol reduction of 0.48 to 0.77 % (v/v) in sequential fermentations, with increased concentrations of lactic and acetic acids. The highest reduction was achieved when the inoculum concentration of non-Saccharomyces was ten times higher (10⁷ cells/mL) than that of S. cerevisiae. 

New article on diversity of Brettanomyces bruxellensis

Genetic and phenotypic diversity of Brettanomyces bruxellensis isolates from ageing wines

Jessica Lleixà, Maria Martínez-Safont, Isabelle Masneuf-Pomarede, Maura Magani, Warren Albertin, Albert Mas, M. Carmen Portillo 

Food Bioscience 2021, 40, 100900. https://doi.org/10.1016/j.fbio.2021.100900

    Brettanomyces bruxellensis is the most reported spoilage yeast in aged wines mainly due to the production of phenolic off-flavors. 

    In the present study, 64 B. bruxellensis strains isolated from Catalonian ageing wines were genetically and physiologically evaluated using ISS-PCR and microsatellite analysis. High intraspecific diversity was found depending mostly on the origin of isolation and both the resistance to SO₂ and the production of volatile phenols varied within the strains. 

    This complexity must be taken into account to optimize both monitoring and corrective interventions, suggesting the importance of an early detection.

 

New research project on microbial consortia of wine

Establishment of microbial consortia for the improvement of wine quality and stability

Reference PID2019-108722RCB-C33, Spanish Ministerio de Ciencia e Innovación. Leader reaserchers: Mª Jesús Torija & Gemma Beltran. 2020-2023.

During alcoholic fermentation (AF), yeasts can synthesize, from aromatic amino acids, compounds of special interest such as higher alcohols and esters, but also some bioactive compounds that can contribute to the quality and stability of wines, such as melatonin (MEL), serotonin or hydroxytyrosol (HT), among others (aromatic amino acid-derived compounds, AADC). This project aims to deepen the potential impact of these molecules on the sensory properties together with their possible antioxidant and antimicrobial effect on wine. 

In the previous projects (BIOACTIYEAST and SYNBIOFERM), we have improved our knowledge about the synthesis of these bioactive molecules (mainly MEL) by yeasts during AF. We could observe that MEL is synthesized by yeasts during the lag or early exponential phase, but there was a gap between intracellular production and secretion to the extracellular medium, during the exponential or stationary phase. Our results showed that during this period MEL is bound to some glycolytic enzymes, only in yeasts with high fermentative capacity. The interaction of MEL with these proteins suggested the presence of a glycolytic complex, and our hypothesis is that MEL can act as a positive or negative regulator of this complex to channel the flow to the fermentative metabolism.

 

Therefore, different yeasts (Saccharomyces and non-Saccharomyces (NS)) and different physiological conditions (fermentation vs. respiration) were used, as well as tdifferent yeast mutants, in order to decipher the metabolic role of MEL in yeasts. Likewise, our results also showed that the presence of MEL increased the proportion of NS at the end of fermentation. In addition, contrary to what we observed in individual fermentations, higher extracellular levels of MEL were detected when a mixed inoculum of Saccharomyces and NS was used, pinpointing towards an effect of the microbiota present during fermentation in the synthesis of AADC. 

 

For this reason, the main objective of this project is to exploit the great metabolic diversity of yeasts and lactic acid bacteria (LAB) to increase the concentration of these bioactive molecules in wines. Therefore, we will first select the strains with the highest AADC synthesis capacity, to be then used for the design of microbial consortia. In some cases, yeasts will be improved by non-GM techniques in order to maximize this AADC production. In the designed consortia, microbial, metabolic and molecular interactions will be evaluated during fermentation, using different inoculation strategies (inoculation ratios, with and without cell contact). These selected consortia will be tested on a laboratory scale to determine the optimal oenological conditions for increasing the production of AADC in wines. Finally, the impact of this higher concentration of AADC on wines will be analyzed in terms of organoleptic quality and stability (antioxidant and antimicrobial).

Enoforum web Conference

 23-25th February 2021, International Congress, free upon registration: 

https://www.enoforum.eu/en/enoforum-web-conference-2021/