9 results on '"Albert Mas"'
Search Results
2. EQUACIONS EN DERIVADES PARCIALS | PARCIAL
- Author
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Cabré Vilagut, Xavier, Albert Mas, Cabré Vilagut, Xavier, and Albert Mas
- Abstract
Parcial amb solucions, Resolved, 2022-2023, 2n quadrimestre
- Published
- 2023
Catalog
3. Microbiome dynamics during spontaneous fermentations of sound grapes in comparison with sour rot and Botrytis infected grapes
- Author
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Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, Jessica Lleixà; Dimitrios Kioroglou; Albert Mas, Maria del Carmen Portillo, Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, and Jessica Lleixà; Dimitrios Kioroglou; Albert Mas, Maria del Carmen Portillo more...
- Abstract
The main losses in viticulture around the world are normally associated with rotten grapes affecting both the chemical composition and the grape microbiota that later might affect the alcoholic fermentation. We analyzed the population in musts obtained from sour rotten, botrytized and healthy Macabeo grapes and the population dynamics during the spontaneous alcoholic fermentation by culture dependent and various culture independent methods including, for the first time, qPCR and massive sequencing. Grape health state affected the fermentation kinetics and also the microbial diversity and composition. Unexpectedly, the fermentation proceeded the fastest in the rotten must followed by the healthy and the botrytized grapes. As in previous studies, plate cell counts and qPCR results confirmed the increase in the number of both bacteria and fungi in the musts from damaged grapes. Massive sequencing detected higher biodiversity than the other techniques at each stage, with Saccharomyces and Oenococcus found already in the grape must. Hanseniaspora osmophila replaced to Hanseniaspora uvarum as the predominant yeast during the mid-fermentation stage for both damaged grapes. Furthermore, musts and beginning of fermentation from rotten and botrytized grapes consistently had a higher presence of the fungi Zygosaccharomyces, Penicillium and Aspergillus while high abundance of Botrytis were observed just for botrytized grapes. As expected, the acetic acid bacteria number increased in musts from rotten and botrytized grapes, mostly due to changes in proportion of the genus Gluconoacetobacter which remained more abundant during damaged grapes fermentation than during healthy ones. Interestingly, the presence of Oenococcus oeni at the end of the alcoholic fermentation was strongly affe more...
- Published
- 2018
4. Microbiome dynamics during spontaneous fermentations of sound grapes in comparison with sour rot and Botrytis infected grapes
- Author
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Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, Jessica Lleixà; Dimitrios Kioroglou; Albert Mas, Maria del Carmen Portillo, Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, and Jessica Lleixà; Dimitrios Kioroglou; Albert Mas, Maria del Carmen Portillo more...
- Abstract
The main losses in viticulture around the world are normally associated with rotten grapes affecting both the chemical composition and the grape microbiota that later might affect the alcoholic fermentation. We analyzed the population in musts obtained from sour rotten, botrytized and healthy Macabeo grapes and the population dynamics during the spontaneous alcoholic fermentation by culture dependent and various culture independent methods including, for the first time, qPCR and massive sequencing. Grape health state affected the fermentation kinetics and also the microbial diversity and composition. Unexpectedly, the fermentation proceeded the fastest in the rotten must followed by the healthy and the botrytized grapes. As in previous studies, plate cell counts and qPCR results confirmed the increase in the number of both bacteria and fungi in the musts from damaged grapes. Massive sequencing detected higher biodiversity than the other techniques at each stage, with Saccharomyces and Oenococcus found already in the grape must. Hanseniaspora osmophila replaced to Hanseniaspora uvarum as the predominant yeast during the mid-fermentation stage for both damaged grapes. Furthermore, musts and beginning of fermentation from rotten and botrytized grapes consistently had a higher presence of the fungi Zygosaccharomyces, Penicillium and Aspergillus while high abundance of Botrytis were observed just for botrytized grapes. As expected, the acetic acid bacteria number increased in musts from rotten and botrytized grapes, mostly due to changes in proportion of the genus Gluconoacetobacter which remained more abundant during damaged grapes fermentation than during healthy ones. Interestingly, the presence of Oenococcus oeni at the end of the alcoholic fermentation was strongly affe more...
- Published
- 2018
5. GqqA, a novel protein in Komagataeibacter europaeus involved in bacterial quorum quenching and cellulose formation
- Author
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Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, Maria José Valera; Albert Mas; Wolfgang R. Streit; Estibaliz Mateo, Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, and Maria José Valera; Albert Mas; Wolfgang R. Streit; Estibaliz Mateo more...
- Abstract
Background: We report on the functional screening and identification of an active quorum quenching (QQ) gene in the Komagataeibacter europaeus strain CECT 8546, which is a member of the acetic acid bacteria (AAB). Results: Using a previously published screening protocol (Schipper et al., in Appl Environ Microbiol 75:224-233, 2009. doi: 10.1128/AEM.01389-08 ) for QQ genes, we identified a single gene, designated gqqA, that interfered strongly with bacterial quorum sensing (QS) in various reporter strains. It encodes for a 281-amino acid protein with a molecular mass of 30 kDa. Although the GqqA protein is similar to predicted prephenate dehydratases, it does not complement Escherichia coli mutants of the pheA gene, thus indicating a potentially different function. Recombinant GqqA protein attenuated QS-dependent pyocyanin production and swarming motility in the Pseudomonas aeruginosa strain PAO1. Moreover, GqqA quenched the QS response of the Agrobacterium tumefaciens NTL4 and the Chromobacterium violaceum CV026 reporter strains. Interestingly, the addition of recombinant GqqA protein to growing cultures of the Komagataeibacter europaeus strain CECT 8546 altered the cellulose production phenotype of CECT 8546 and other AAB strains. In the presence of GqqA protein, cells were planktonic, and no visible cellulose biofilms formed. The addition of low levels of N-acylhomoserine lactones maintained the biofilm formation phenotype. Conclusions: Our data provide evidence for an interconnection between QS and AAB cellulose biofilm formation as well as QQ activity of the GqqA protein. more...
- Published
- 2016
6. The interaction between Saccharomyces cerevisiae and non-Saccharomyces yeast during alcoholic fermentation is species and strain specific
- Author
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Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, Albert Mas; Chunxiao Wang; Braulio Esteve-Zarzoso, Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, and Albert Mas; Chunxiao Wang; Braulio Esteve-Zarzoso more...
- Abstract
DOI: 10.3389/fmicb.2016.00502, The present study analyzes the lack of culturability of different non-Saccharomyces strains due to interaction with Saccharomyces cerevisiae during alcoholic fermentation. Interaction was followed in mixed fermentations with 1:1 inoculation of S. cerevisiae and ten non-Saccharomyces strains. Starmerella bacillaris, and Torulaspora delbrueckii indicated longer coexistence in mixed fermentations compared with Hanseniaspora uvarum and Metschnikowia pulcherrima. Strain differences in culturability and nutrient consumption (glucose, alanine, ammonium, arginine, or glutamine) were found within each species in mixed fermentation with S. cerevisiae. The interaction was further analyzed using cell-free supernatant from S. cerevisiae and synthetic media mimicking both single fermentations with S. cerevisiae and using mixed fermentations with the corresponding non-Saccharomyces species. Cell-free S. cerevisiae supernatants induced faster culturability loss than synthetic media corresponding to the same fermentation stage. This demonstrated that some metabolites produced by S. cerevisiae played the main role in the decreased culturability of the other non-Saccharomyces yeasts. However, changes in the concentrations of main metabolites had also an effect. Culturability differences were observed among species and strains in culture assays and thus showed distinct tolerance to S. cerevisiae metabolites and fermentation environment. Viability kit and recovery analyses on non-culturable cells verified the existence of viable but not-culturable status. These findings are discussed in the context of interaction between non-Saccharomyces and S. cerevisiae. more...
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- 2016
7. Saccharomyces and non-Saccharomyces competition during microvinification under different sugar and nitrogen conditions
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Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, Albert Mas; Jessica Lleixà; Maria Manzano; María del C. Portillo, Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, and Albert Mas; Jessica Lleixà; Maria Manzano; María del C. Portillo more...
- Abstract
The inoculation of wines with autochthonous yeast allows obtaining complex wines with a peculiar microbial footprint characteristic from a wine region. Mixed inoculation of non-Saccharomyces yeasts and S. cerevisiae is of interest for the wine industry for technological and sensory reasons. However, the interactions between these yeasts are not well understood, especially those regarding the availability of nutrients. The aim of the present study was to analyze the effect of nitrogen and sugar concentration on the evolution of mixed yeast populations on controlled laboratory-scale fermentations monitored by density, plate culturing, PCR-DGGE and sugar and nitrogen consumption. Furthermore, the effect of the time of inoculation of Saccharomyces cerevisiae respect the initial co-inoculation of three non-Saccharomyces yeasts was evaluated over the evolution of fermentation. Our results have shown that S. cerevisiae inoculation during the first 48 h conferred a stabilizing effect over the fermentations with non-Saccharomyces strains tested and, generally, reduced yeast diversity at the end of the fermentation. On the other hand, nitrogen limitation increased the time of fermentation and also the proportion of non-Saccharomyces yeasts at mid and final fermentation. High sugar concentration resulted in different proportions of the inoculated yeast depending on the time of S. cerevisiae inoculation. This work emphasizes the importance of the concentration of nutrients on the evolution of mixed fermentations and points to the optimal conditions for a stable fermentation in which the inoculated yeasts survived until the end. more...
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- 2016
8. Determination of dehydrogenase activities involved in D-glucose oxidation in Gluconobacter and Acetobacter strains
- Author
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Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, María Jesús Torija; Florencia Sainz; Minenosuke Matsutani; Naoya Kataoka; Toshiharu Yakushi; Kazunobu Matsushita; Albert Mas, Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, and María Jesús Torija; Florencia Sainz; Minenosuke Matsutani; Naoya Kataoka; Toshiharu Yakushi; Kazunobu Matsushita; Albert Mas more...
- Abstract
Acetic acid bacteria (AAB) are known for rapid and incomplete oxidation of an extensively variety of alcohols and carbohydrates, resulting in the accumulation of organic acids as the final products. These oxidative fermentations in AAB are catalyzed by PQQ- or FAD- dependent membrane-bound dehydrogenases. In the present study, the enzyme activity of the membrane-bound dehydrogenases [membrane-bound PQQ-glucose dehydrogenase (mGDH), D-gluconate dehydrogenase (GADH) and membrane-bound glycerol dehydrogenase (GLDH)] involved in the oxidation of D-glucose and D-gluconic acid (GA) was determined in six strains of three different species of AAB (three natural and three type strains). Moreover, the effect of these activities on the production of related metabolites [GA, 2-keto-D-gluconic acid (2KGA) and 5-keto-D-gluconic acid (5KGA)] was analyzed. The natural strains belonging to Gluconobacter showed a high mGDH activity and low activity in GADH and GLDH, whereas the Acetobacter malorum strain presented low activity in the three enzymes. Nevertheless, no correlation was observed between the activity of these enzymes and the concentration of the corresponding metabolites. In fact, all the tested strains were able to oxidize D-glucose to GA, being maximal at the late exponential phase of the AAB growth (24 h), which coincided with D-glucose exhaustion and the maximum mGDH activity. Instead, only some of the tested strains were capable of producing 2KGA and/or 5KGA. In the case of Gluconobacter oxydans strains, no 2KGA production was detected which is related to the absence of GADH activity after 24 h, while in the remaining strains, detection of GADH activity after 24 h resulted in a high accumulation of 2KGA. Therefore, it is possible to choose the best strain depending on the more...
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- 2016
9. Analysis of microbial diversity and dynamics during wine fermentation of Grenache grape variety by high-throughput barcoding sequencing
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Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, Maria del Carmen Portillo; Albert Mas, Biotecnologia Enològica, Bioquímica i Biotecnologia, Universitat Rovira i Virgili, and Maria del Carmen Portillo; Albert Mas more...
- Abstract
Understanding the diversity and evolution of microorganisms during wine fermentation is essential for controlling its production. Previous studies have been primarily based on culture-dependent methods but recent incorporation of culture-independent molecular methods is showing a quite different view of microbial composition and diversity during the wine making process. Herein we applied barcoded pyrosequencing technology to monitor bacterial and yeast dynamics during laboratory scale spontaneous wine fermentation from Grenache variety. Members of the lactic acid bacteria (LAB) and acetic acid bacteria (AAB) were the most abundant, representing the orders Lactobacillales and Rhodospirillales more than 70% of the bacterial population. Other bacterial genera, not previously detected at the end of fermentation, were present in low proportion and their possible role remains unknown. Within the yeast community, the genera Hanseniaspora and Candida were dominant during the initial and mid fermentation while the final fermentation was mainly dominated by Candida and Saccharomyces. This study contributes to the knowledge of the microbial dynamics across spontaneous wine fermentation and presents high-throughput sequencing as a useful tool to monitor and evaluate bacterial and yeast diversity and dynamics during wine fermentation. more...
- Published
- 2016
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