Search results for " Fermentation"
showing 10 items of 283 documents
Antibacterial effect of the bioactive compound beauvericin produced by Fusarium proliferatum on solid medium of wheat.
2010
To obtain the bioactive compound beauvericin (BEA), Fusarium proliferatum CECT 20569 was grown on a solid medium of wheat, utilizing the technique of the solid state fermentation (SSF), being this mycotoxin purified by high performance liquid chromatography (HPLC) with a reverse phase semi-preparative column using as the mobile phase acetonitrile/water in gradient condition. The purity of the BEA was verified by analytical HPLC and liquid chromatography tandem mass spectrometry (LC/MS-MS). The pure fractions of BEA were utilized to determinate the antibiotic effects on several bacterial strains that are considered normally pathogens of the intestinal tract as: Escherichia coli, Enterococcus…
An Exemplary Model Study for Overcoming Stuck Fermentation during Spontaneous Fermentation with the Aid of a Saccharomyces Triple Hybrid
2015
Sluggish or stuck fermentations cause significant financial losses for winemakers each year. In order to investigate the reasons for problems during spontaneous fermentation of Riesling must in a well-known German vineyard of the lower Moselle, yeast strains involved in must fermentation were identified during winemaking in the two years 2011 and 2012. Identification of the yeast isolates was performed by applying analyses of the ITS-1-5.8-ITS2 region and restriction fragment analyses of different gene sequences. It revealed that Saccharomyces (S.) bayanus and not Saccharomyces cerevisiae was the main fermenting yeast. Either S. bayanus finished the fermentation or led to stuck fermentation…
Using neural networks to obtain indirect information about the state variables in an alcoholic fermentation process
2020
This work provides a manual design space exploration regarding the structure, type, and inputs of a multilayer neural network (NN) to obtain indirect information about the state variables in the alcoholic fermentation process. The main benefit of our application is to help experts reduce the time needed for making the relevant measurements and to increase the lifecycles of sensors in bioreactors. The novelty of this research is the flexibility of the developed application, the use of a great number of variables, and the comparative presentation of the results obtained with different NNs (feedback vs. feed-forward) and different learning algorithms (Back-Propagation vs. Levenberg&ndash
Quantifying the individual effects of ethanol and temperature on the fitness advantage of Saccharomyces cerevisiae
2011
The presence of Saccharomyces cerevisiae in grape berries and fresh musts is usually very low. However, as fermentation progresses, the population levels of this species considerably increase. In this study, we use the concept of fitness advantage to measure how increasing ethanol concentrations (0-25%) and temperature values (4-46 °C) in wine fermentations affects competition between S. cerevisiae and several non-Saccharomyces yeasts (Hanseniaspora uvarum, Torulaspora delbrueckii, Candida zemplinina, Pichia fermentans and Kluyveromyces marxianus). We used a mathematical approach to model the hypothetical time needed for S. cerevisiae to impose itself on a mixed population of the non-Saccha…
Absence of malolactic activity is a characteristic of H+-ATPase-deficient mutants of the lactic acid bacterium Oenococcus oeni.
2003
ABSTRACT The lack of malolactic activity in H + -ATPase-deficient mutants of Oenococcus oeni selected previously was analyzed at the molecular level. Western blot experiments revealed a spot at 60 kDa corresponding to the malolactic enzyme only in the parental strain. Moreover, the mleA transcript encoding the malolactic enzyme was not detected by reverse transcription (RT)-PCR analysis of mutants. These results suggest that the malolactic operon was not transcribed in ATPase-deficient mutants. The mleR gene encoding a LysR-type regulatory protein which should be involved in expression of the malolactic genes was described previously for O. oeni . Results obtained in this study show that th…
Regulation of stress response in Oenococcus oeni as a function of environmental changes and growth phase
2000
International audience; Oenococcus oeni is a lactic acid bacterium which is able to grow in wine and perform malolactic fermentation. To survive and grow in such a harsh environment as wine, O. oeni uses several mechanisms of resistance including stress protein synthesis. The molecular characterisation of three stress genes hsp18, clpX, trxA encoding for a small heat shock protein, an ATPase regulation component of ClpP protease and a thioredoxin, respectively, allow us to suggest the existence in O. oeni of multiple regulation mechanisms as is the case in Bacillus subtilis. One common feature of these genes is that they are expressed under the control of housekeeping promoters. The express…
Procédé de Liquéfaction, Saccharification et Fermentation Simultanée à Très Haute Gravité utilisant de la farine de manioc pour la production de l'ét…
2021
A simultaneous liquefaction, saccharification and fermentation (SLSF) process at very high gravity of cassava flour for potable ethanol production was developed at lab (1 L) and pilot scale (15 L and 1000 L). Cassava flour (CF) was mixed with tap water to obtain a concentration of 270 g/L dry matter. Sequentially, the mixture of a native starch hydrolyzing enzyme containing a mixture of alpha–amylase and gluco-amylase (Stargen 002 at 2565 GAU/kg CF), gluco-amylase (Amigase Mega L at 0.105% w/w), active dry yeast Saccharomyces cerevisiae (Red Ethanol at 3,5 × 10^7 cells/ml), KH2PO4 (9,9 mM) and urea (16.0 mM) was added into cassava slurry. The SLSF-VHG process including three steps of liquef…
Persistence of a mixed lactic acid bacterial starter culture during lysine fortification of sourdough breads by addition of pistachio powder
2020
Abstract Pistachio powder was added to flour or semolina to evaluate its contribution to increase the amount of lysine in bread. Bread production was carried out by sourdough technology using a selected 3-species (Lactobacillus sanfranciscensis/Leuconostoc citreum/Weissella cibaria) lactic acid bacterial (LAB) starter culture. All sourdoughs were subjected to a long-time fermentation (21 h) and showed levels of LAB around 109 CFU/g, indicating the suitability of pistachio powder for lactic fermentation. Yeasts were also detected, in particular in semolina trials. MiSeq Illumina technology was applied to investigate the bacterial composition of sourdoughs evidencing a different distribution …
Non-conventional yeasts from fermented honey by-products: Focus on Hanseniaspora uvarum strains for craft beer production
2021
The increasing interest in novel beer productions focused on non-Saccharomyces yeasts in order to pursue their potential in generating groundbreaking sensory profiles. Traditional fermented beverages represent an important source of yeast strains which could express interesting features during brewing. A total of 404 yeasts were isolated from fermented honey by-products and identified as Saccharomyces cerevisiae, Wickerhamomyces anomalus, Zygosaccharomyces bailii, Zygosaccharomyces rouxii and Hanseniaspora uvarum. Five H. uvarum strains were screened for their brewing capability. Interestingly, Hanseniaspora uvarum strains showed growth in presence of ethanol and hop and a more rapid growth…
Effects of different yeast strains, nutrients and glutathione-rich inactivated yeast addition on the aroma characteristics of Catarratto wines
2021
Catarratto is one of the most common non-aromatic white grape varieties cultivated in Sicily (Southern Italy). In order to improve the aromatic expression of Catarratto wines a trial was undertaken to investigate the effect of yeast strain, nutrition and reduced glutathione. Variables included two Saccharomyces cerevisiae strains, an oenological strain (GR1) and one isolated from honey by-products (SPF52), three different nutrition regimes (Stimula Sauvignon Blanc™ (SS), Stimula Chardonnay™ (SC) and classic nutrition practice), and a specific inactivated yeast rich in reduced glutathione to prevent oxidative processes [Glutastar™ (GIY)] ensuing in ten treatments (T1-T10). Microbiological an…