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/

Online group meeting and Merry Christmas to everybody

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.

We wish Merry Christmas to everybody, and a better and free-covid 2021 !!!

New article on the effect of melatonin in transcriptomics of S. cerevisiae

Transcriptomic insight into the effect of melatonin in Saccharomyces cerevisiae in the presence and absence of oxidative stress

Mercè Sunyer-Figueres, Jenny Vázquez, Albert Mas, M. Jesús Torija, Gemma Beltran

Antioxidants 2020, 9, 947.  https://www.mdpi.com/2076-3921/9/10/947

  Melatonin plays important roles in biological processes in humans, so its study has growing interest. Saccharomyces cerevisiae produces melatonin during alcoholic fermentation, and recent studies report that it has an antioxidant role in yeast cells, not only directly neutralizing the effects of oxidative stress, also modulating the expression of genes involved in antioxidant response.

  In order to study the effects of melatonin in the global gene response of yeast, we determined the transcriptomic state of cells that were supplemented with melatonin and exposed or non-exposed to oxidative stress.

  We found that melatonin crossed cellular membranes and regulated the transcription of several genes, related to transport, signaling, antioxidant activity or several metabolisms. The most regulated genes by melatonin were the mitochondrial ones (mainly those related to electron transport chain), and its expression was downregulated in absence of oxidative stress and upregulated in its presence. Therefore, we concluded that melatonin can reprogram different cellular processes to achieve tolerance to oxidative stress.

New article on the favourable impact of Torulaspora delbrueckii on malolactic fermentation

Impact of changes in wine composition produced by non-Saccharomyces on malolactic fermentation

Aitor Balmaseda, Nicolas Rozès, Miguel Ángel Leal, Albert Bordons, Cristina Reguant

International Journal of Food Microbiology 2021, 337, 108954. https://doi.org/10.1016/j.ijfoodmicro.2020.108954

    Nowadays, non-Saccharomyces yeasts have increasing interest in winemaking. This is particularly true of Torulaspora delbrueckii and Metschnikowia pulcherrima, which are inoculated before S. cerevisiae, in so called sequential inoculation. As result of the different yeast combination, wine chemical characteristics are modulated. 

    In this sense, not only aromatic and colour parameters are influenced, but also those compounds related to the performance of the subsequent malolactic fermentation. Oenococcus oeni is the main species which carries out this fermentative process, will be positively, neutrally or negatively affected by the result of the fermenting yeast's metabolisms. Indeed, novel researches in this field postulate some non-Saccharomyces as good culture starter combination together with O. oeni for developing malolactic fermentation. 

    This paper aims to study the effects of those two non-Saccharomyces yeasts on malolactic fermentation carried out by two strains of O. oeni and also a spontaneous fermentation, under cellar conditions. Studying both, white and red winemaking processes. In general, non-Saccharomyces created more MLF friendly conditions, largely because of lower concentrations of SO2 and medium chain fatty acids. The most favourable results were observed in wines inoculated with T. delbrueckii, that seemed to promote the development of O. oeni and improve MLF performance. 

New article on the effect of non-Saccharomyces on malolactic fermentation and Oenococcus oeni

Evaluating the effect of using non-Saccharomyces on Oenococcus oeni and wine malolactic fermentation

Núria Ferrando, Isabel Araque, Alba Ortís, Gabriel Thornes, Joaquín Bautista-Gallego, Albert Bordons, Cristina Reguant

Food Research International 2020, 138 B, 109779 https://doi.org/10.1016/j.foodres.2020.109779

    Interest in using non Saccharomyces yeasts in winemaking has increased recently due to their ability to improve organoleptic characteristics. Since there is little information on their effects on malolactic fermentation (MLF) and Oenococcus oeni, we studied it with different strains of Torulaspora delbrueckii, Metschnikowia pulcherrima, Hanseniaspora uvarum, H. vineae and Starmerella bacillaris (syn. Candida zemplinina). We used them in sequential alcoholic fermentation with S. cerevisiae, followed by inoculation with four O. oeni strains. 

    The main results were that some of O. oeni strains could not perform MLF in H. uvarum wine and in some cases, MLF was inhibited in S. bacillaris wines. Also, all the H. uvarum and H. vineae strains increased notably acetic acid and some of them increased SO₂. On the contrary, the best conditions for MLF were provided by some T. delbruecckii and M. pulcherrima strains, with increased concentrations of mannoproteins, no production of SO₂, and low consumption of L-malic acid. In conclusion, these species T. d. and M. p. showed the best compatibility with MLF development.