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.
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.
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.
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.
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).
23-25th February 2021, International Congress, free upon registration:
https://www.enoforum.eu/en/enoforum-web-conference-2021/
Last Friday 18th December we have celebrated an online meeting of Wine Biotechnology Research Group.
The last results of different projects have been discussed and our colleague M. Ángeles Morcillo (postdoctoral researcher) has presented her last results on melatonin in yeasts.
