Search results for "Oenococcus"
showing 10 items of 85 documents
A small HSP, Lo18, interacts with the cell membrane and modulates lipid physical state under heat shock conditions in a lactic acid bacterium
2005
International audience; The small heat shock proteins (sHSP) are characterized by a chaperone activity to prevent irreversible protein denaturation. This study deals with the sHSP Lo18 induced by multiple stresses in Oenococcus oeni, a lactic acid bacterium. Using in situ immunocytochemistry and cellular fractionation experiments, we demonstrated the association of Lo18 with the membrane in O. oeni cells submitted to heat shock. The same result was obtained after exposure of cells to ethanol or benzyl alcohol, agents known to have an influence on membranes. For the different stresses, the protein was located on the periphery of the cell at membrane level and was also found within the cytopl…
Protective role of glutathione addition against wine-related stress in Oenococcus oeni
2016
FIliació URV: SIInclòs a la memòria: SI Oenococcus oeni is the main species responsible for the malolactic fermentation (MLF) of wine due to its ability to survive in this environment. Some wine-related stress factors, such as ethanol and low pH, may alter the cell redox balance of O. oeni. For the first time, the ability to uptake glutathione (GSH), an almost universal tripeptide with antioxidant properties, has been associated to the improvement of stress response in O. oeni. Despite the inability of O. oeni to synthesize GSH, this bacterium can capture it from the media. The ability of 30 O. oeni strains to uptake GSH was assessed in this study. Although all of the strains tested were ab…
Significance of pantothenate for glucose fermentation by Oenococcus oeni and for suppression of the erythritol and acetate production.
2001
The heterofermentative lactic acid bacterium Oenococcus oeni requires pantothenic acid for growth. In the presence of sufficient pantothenic acid, glucose was converted by heterolactic fermentation stoichiometrically to lactate, ethanol and CO2. Under pantothenic acid limitation, substantial amounts of erythritol, acetate and glycerol were produced by growing and resting bacteria. Production of erythritol and glycerol was required to compensate for the decreasing ethanol production and to enable the synthesis of acetate. In ribose fermentation, there were no shifts in the fermentation pattern in response to pantothenate supply. In the presence of pantothenate, growing O. oeni contained at l…
Molecular mechanisms involved in the regulation of stress response in Oenococcus oeni and experimental evolution
2020
Oenococcus oeni is the main bacterium responsible of malolactic fermentation in wine. This lactic acid bacteria grow in the stressful wine environment (high ethanol content, sulfites, low pH and low temperatures….). To maintain its cellular homeostasis, O. oeni has established mechanisms of resistance to its ecological niche. This research work focuses on the adaptative response of O. oeni to its environment and especially to acidity. Two approaches have been implemented (1) First, a targeted approach to characterize the molecular actors involved in regulating the general stress response. The RNA interference technique made possible the characterization of the repressor CtsR as well as two …
Interactions micro-organismes - bois et impact sur les propriétés physico-chimiques du vin : fermentation malolactique par le biofilm de Oenococcus o…
2015
Malolactic fermentation improves wine quality, mainly by decreasing acidity. It is carried out by lactic acid bacteria, mainly Oenococcus oeni. This species is favored for its efficiency and its organoleptic outcome. O. oeni ability to withstand wine stress and to keep its fermentation activity is a subject of major interest.Samples of oak showed that O. oeni adheres to wood and is able to persist for several months in wine. However, in the majority of natural habitats, microorganisms grow attached to a surface, within a structured ecosystem called biofilm. In this form of life, cells benefit from an increased stress resistance.These two properties, adherence to a surface and stress resista…
Value of recN sequences for species identification and as a phylogenetic marker within the family “Leuconostocaceae”
2008
The genera Leuconostoc, Oenococcus, and Weissella (family “Leuconostocaceae”) constitute a group of lactic acid bacteria of great interest in food microbiology. From the taxonomic point of view, they are considered phylogenetically coherent according to their 16S rRNA gene sequences and other macromolecules. These three genera were the focus of the present study; specifically, the resolution and discriminatory power of recN (encoding a DNA repair and genetic recombination protein) as a molecular marker at the species level were investigated. For this purpose, partial sequences (about 1200 nt) were obtained from 23 type strains and from several additional strains following direct amplificati…
Lysis of yeast cells by Oenococcus oeni enzymes
2000
exhibited extracellular β (1→3) glucanase activity. This activity increased when cells were cultivated with glycosidic cell-wall macromolecules. In addition, the culture supernatant of the organism effectively lysed viable or dead cells of Saccharomyces cerevisiae. This lytic activity appeared in the early stationary phase of bacterial growth. Yeast cells at the end of the log phase of growth were the most sensitive. The optimum temperature for lysis of viable yeast cells was 40°C, which is very different from the temperatures observed in enological conditions (15–20°C). Moreover, the rate of the lytic activity was significantly lower in comparison with yeast cell wall-degrading activities …
Increase of sulfite tolerance in Oenococcus oeni by means of acidic adaptation
1998
International audience; Sulfite is an antimicrobial agent used at the beginning of winemaking to avoid development of undesirable microorganisms. However, Oenococcus oeni, which is mainly responsible for the malolactic fermentation, has to grow in wine and therefore has to be resistant to sulfite. This study showed that acid-adapted cells of O. oeni survived better than non-adapted cells in the presence of a high sulfite concentration (30 mg l-1). Addition of a sub-lethal concentration of sulfite (15 mg l31) during the adaptation step in acidic medium increases the sulfite tolerance. Moreover, sulfite appeared to be able to induce a heat shocklike response. Our results suggest that pH homeo…
Peptidases specific for proline-containing peptides and their unusual peptide-dependent regulation in Oenococcus oeni
2009
International audience; Growth of the lactic acid bacterium (LAB) Oenococcus oeni, which is involved in malolactic fermentation during the winemaking process, is stimulated by peptides originating from yeast. In this study, we investigated the impact of peptides on O. oeni growth, peptidase activity and the expression of genes encoding the studied peptidases. Low levels of PepN activity and very high levels of PepI activity were observed in O. oeni, whereas levels of PepX activity were intermediate. The level of biosynthesis of these O. oeni peptidases was shown to depend on peptides present in the culture medium. These results were confirmed by transcriptional analyses of putative pep gene…
Oligopeptide assimilation and transport by Oenococcus oeni
2008
International audience; Aims: Oenococcus oeni is a slow-growing wine bacterium with a low growth yield. It thrives better on complex nitrogen sources than on free amino-acid medium. We aimed to characterize the oligopeptide use of this micro-organism. Methods and Results: Several peptides of two to eight amino-acid residues were able to provide essential amino acids. The disappearance of various peptides from extracellular medium was assessed with whole cells. Initial rates of utilization varied with the peptide, and free amino acids were released into the medium. Conclusions: Oenococcus oeni was able to transport the oligopeptides with two to five amino-acid residues tested and to hydrolys…