Search results for "bacteria."
showing 10 items of 4757 documents
Molecular Identification and Characterization of Wine Yeasts
2011
The transformation of grape must into wine is a complex microbiological process involving the sequential growth of bacteria and yeasts, although only the yeasts are responsible for alcoholic fermentation. In the past, winemaking was purely empirical, but it is now a well-understood, controlled process that has been gradually improved over time. Advances have largely been made possible by the development of molecular techniques to identify and characterize wine yeasts based on analysis of their DNA. These methods are rapid, reproducible, and sensitive, and continue to be used for a variety of purposes, such as analyzing variation in naturally occurring and inoculated yeast populations, monit…
The effects of freezing and freeze-drying ofOenococcus oeniupon induction of malolactic fermentation in red wine
2000
Summary The use of Oenococcus oeni starter cultures for the induction of malolactic fermentation (MLF) in wine permits control over the timing of the process and the quality of the wine. Successful inoculation of bacterial starter cultures into wine depends on the selection of suitable strains and on the preparation and conservation of those cultures. Medium for Leuconostoc oenos (MLO) is the best medium for easy and rapid growth of O. oeni cultures under laboratory controlled conditions for isolation and identification. However, this study showed that O. oeni cells inoculated in MLO failed to induce MLF in wine while cells grown in Medium of Preculture (MP) or wine, stored at −20 °C or fre…
Influence of epigallocatechin gallate and phenolic compounds from green tea on the growth of Oenococcus oeni
2007
Aims: To investigate the effect of phenolic compounds on the growth of Oenococcus oeni. Methods and Results: Oenococci are usually grown in media often supplemented with complex additives such as tomato juice. In order to improve our knowledge about the growth requirements of oenococci, we added several juices and leaf extracts such as green tea to the culture media and screened them for growth-stimulating substances to substitute complex supplements such as juices by more defined components. We found that also green tea could cause a growth stimulation of Oenococcus oeni strain B2. Conclusions: Further experiments showed that the stimulating effect was as a result of the phenolic compou…
Activation of wooden vats with selected lactic acid bacteria for the year-round production of traditional Vastedda-like cheese
2014
Vastedda is a pasta filata cheese made from raw ewes’ milk without the addition of starter cultures. Cheese production is carried out in wooden vats characterized by microbial biofilms hosting lactic acid bacteria (LAB) responsible for the acidification of the curds. Vastedda cheese was traditionally produced during the summer season, but it is currently produced throughout the year. In order to minimize production variability, several LAB were isolated from Vastedda PDO cheeses, characterized for their technological potential (Gaglio et al., 2014a) and selected to obtain the best strain combination for the production (Gaglio et al., 2014b). In this study, the multiple strain culture compos…
Electrical conductivity as a state indicator for the start-up period of anaerobic fixed-bed reactors.
2016
The aim of this work was to analyse the applicability of electrical conductivity sensors for on-line monitoring the start-up period of an anaerobic fixed-bed reactor. The evolution of bicarbonate concentration and methane production rate was analysed. Strong linear relationships between electrical conductivity and both bicarbonate concentration and methane production rate were observed. On-line estimations of the studied parameters were carried out in a new start-up period by applying simple linear regression models, which resulted in a good concordance between both observed and predicted values. Electrical conductivity sensors were therefore identified as an interesting method for monitori…
Near-infrared light-responsive and antibacterial injectable hydrogels with antioxidant activity based on a Dopamine-functionalized Gellan Gum for wou…
2022
The development of wound dressings with combined antioxidant, antibacterial and tissue adhesion functions has been a difficult medical task for the treatment of wound infections. We synthetized a dopamine and PEG functionalized Gellan Gum (GG) to produce an injectable hydrogel with radical scavenging activity having both specific and aspecific antibiotic/antimicrobial properties. Using starting GG with different molecular weights, we obtained two derivatives that have been used to prepare the gel precursor dispersion, that undergoes gelation in the presence of colistin and dried microparticles (MPs) functionalized on the surface with polydopamine (pDA). Both were used to dope the hydrogel, …
Mechanism of Antibacterial Activity via Morphology Change of α-AgVO3: Theoretical and Experimental Insights
2017
The electronic configuration, morphology, optical features, and antibacterial activity of metastable α-AgVO3 crystals have been discussed by a conciliation and association of the results acquired by experimental procedures and first-principles calculations. The α-AgVO3 powders were synthesized using a coprecipitation method at 10, 20, and 30 °C. By using a Wulff construction for all relevant low-index surfaces [(100), (010), (001), (110), (011), (101), and (111)], the fine-tuning of the desired morphologies can be achieved by controlling the values of the surface energies, thereby lending a microscopic understanding to the experimental results. The as-synthesized α-AgVO3 crystals display a …
Development and characterization of essential oil component-based polymer films: a potential approach to reduce bacterial biofilm
2013
The development of new polymeric materials aimed to control the bacterial biofilm appears to be an important practical approach. The goal of the present study was to prepare and characterize poly(ethylene-co-vinyl acetate) copolymer (EVA) films containing citronellol, eugenol, and linalool and evaluate their efficiency on growth and biofilm formation of Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa in monospecies and dual species. The results showed that the addition of oil components influenced the elastic modulus (15 % decrease), the tensile stress (30 % decrease), the elongation at break (10 % increase), and the co…
Cutting Edge: An IL-17F-CreEYFP Reporter Mouse Allows Fate Mapping of Th17 Cells
2009
Abstract The need for reporter lines able to faithfully track Th17 cells in vivo has become an issue of exceptional importance. To address this, we generated a mouse strain in which Cre recombinase is expressed from the IL-17F promoter. Crossing the IL-17F-Cre allele to a conditional enhanced yellow fluorescent protein (EYFP) reporter mouse yielded the IL-17F-CreEYFP strain, in which IL-17F expression is twinned with EYFP in live IL-17F-expressing cells. Although we demonstrate that IL-17F expression is restricted to CD4+ T cells during experimental autoimmune encephalomyelitis, IL-17F-CreEYFP CD8 T cells robustly expressed IL-17F in response to TGF-β, IL-6, and IL-23. Fate mapping of IL-17…
Polar Localization of a Tripartite Complex of the Two-Component System DcuS/DcuR and the Transporter DctA in Escherichia coli Depends on the Sensor K…
2014
The C4-dicarboxylate responsive sensor kinase DcuS of the DcuS/DcuR two-component system of E. coli is membrane-bound and reveals a polar localization. DcuS uses the C4-dicarboxylate transporter DctA as a co-regulator forming DctA/DcuS sensor units. Here it is shown by fluorescence microscopy with fusion proteins that DcuS has a dynamic and preferential polar localization, even at very low expression levels. Single assemblies of DcuS had high mobility in fast time lapse acquisitions, and fast recovery in FRAP experiments, excluding polar accumulation due to aggregation. DctA and DcuR fused to derivatives of the YFP protein are dispersed in the membrane or in the cytosol, respectively, when …