Search results for "Oenococcus"
showing 10 items of 85 documents
A new approach for selection of Oenococcus oeni strains in order to produce malolactic starters.
2005
The lactic acid bacterium Oenococcus oeni, mainly responsible for malolactic fermentation (MLF), is used in new winery process as starter culture for direct inoculation. The difficulty to master MLF according to the wine led us to search a new approach to select effective O. oeni strains. Biochemical and molecular tests were performed in order to characterize three strains of O. oeni selected for malolactic starter elaboration. Malolactic and ATPase activities that appeared as a great interest in MLF were measured and the expression of a small heat shock protein Lo18 was evaluated by immunoblotting and real-time PCR. These results were correlated with the performances of strains in two red …
CtsR is the master regulator of stress response gene expression in Oenococcus oeni.
2005
ABSTRACT Although many stress response genes have been characterized in Oenococcus oeni , little is known about the regulation of stress response in this malolactic bacterium. The expression of eubacterial stress genes is controlled both positively and negatively at the transcriptional level. Overall, negative regulation of heat shock genes appears to be more widespread among gram-positive bacteria. We recently identified an ortholog of the ctsR gene in O. oeni . In Bacillus subtilis , CtsR negatively regulates expression of the clp genes, which belong to the class III family of heat shock genes. The ctsR gene of O. oeni is cotranscribed with the downstream clpC gene. Sequence analysis of t…
Changes in membrane lipid composition in ethanol- and acid-adapted Oenococcus oeni cells: characterization of the cfa gene by heterologous complement…
2008
International audience; Cyclopropane fatty acid (CFA) synthesis was investigated in Oenococcus oeni. The data obtained demonstrated that acid-grown cells or cells harvested in the stationary growth phase showed changes in fatty acid composition similar to those of ethanol-grown cells. An increase of the CFA content and a decrease of the oleic acid content were observed. The biosynthesis of CFAs from unsaturated fatty acid phospholipids is catalysed by CFA synthases. Quantitative real-time-PCR experiments were performed on the cfa gene of O. oeni, which encodes a putative CFA synthase. The level of cfa transcripts increased when cells were harvested in stationary phase and when cells were gr…
An improved protocol for electroporation ofOenococcus oeniATCC BAA-1163 using ethanol as immediate membrane fluidizing agent
2008
Aims: To finalize an effective and reproducible electroporation procedure to transform Oenococcus oeni ATCC BAA-1163 strain. Methods and Results: The vector pGID052 was selected to optimize the electroporation procedure. Transformation efficiency was 5·8 × 103 per μg of DNA. Transformation was improved when competent cells were prepared with exponential phase cultures; optimum electroporation parameters were an electric pulse of 12·5 kV cm−1, under a resistance of 200 Ω and the presence of 10% (v/v) ethanol in the electroporation buffer (EPB). Conclusions: An effective protocol to transform O. oeni ATCC BAA-1163 strain by electroporation has been obtained by addition of ethanol to the EP…
Pulsed-field gel electrophoresis for the discrimination of Oenococcus oeni isolates from different wine-growing regions in Germany
2008
Reliable techniques are needed for the identification individual Oenococcus oeni strains with desirable flavor characteristics and to monitor the survival and contribution of inoculated and indigenous bacteria. Therefore, we investigated the suitability of pulsed-field gel electrophoresis (PFGE) for the discrimination of 65 O. oeni isolates from six different wine-producing regions in Germany. Among the restriction enzymes tested, genomic DNA digestions with Sfi I were most effective by displaying 56 (86%) different banding profiles. Our results underline the high capacity of PFGE for strain identification and differentiation. Cluster analysis of the DNA restriction patterns revealed no dis…
Fast protocols for the 5S rDNA and ITS-2 based identification ofOenococcus oeni
2005
To identify specific marker sequences for the rapid identification of Oenococcus oeni, we sequenced the 23S-5S internal transcribed spacer (ITS-2) region and the 5S rDNA of five different O. oeni strains and three phylogenetically related lactic acid bacteria (LAB). Comparative analysis revealed 100% identity among the ITS-2 region of the O. oeni strains and remarkable differences in length and sequence compared to related LAB. These results enabled us to develop a primer set for a rapid PCR-identification of O. oeni within three hours. Moreover, the comparison of the 5S rDNA sequences and the highly conserved secondary structure provided the template for the design of three fluorescence-la…
Conjugative plasmid pIP501 undergoes specific deletions after transfer from Lactococcus lactis to Oenococcus oeni
2003
Conjugal transfer of plasmids pIP501 and its derivative pVA797 from Lactococcus lactis to Oenococcus oeni was assayed by filter mating. Plasmid pIP501 was transferred to a number of O. oeni strains whereas a single transconjugant of O. oeni M42 was recovered when pVA797 was used. Physical analysis of the transconjugant plasmids revealed that pIP501 and pVA797 underwent extensive deletions in O. oeni that affected the tra region (conjugal transfer) and SegB region (stability). All derivatives showed segregational instability in O. oeni, but were stably maintained in L. lactis. These differences correlated with the different plasmid copy numbers and the extent of deletions within the SegB reg…
16S-ARDRA, a tool for identification of lactic acid bacteria isolated from grape must and wine.
2003
Lactic acid bacteria (LAB) are found in a great variety of habitats, including grape must and wines. There is a close relationship between the species of LAB which develop during fermentation and the eventual quality of the wine. For these reasons analytical techniques allowing fast and reliable identification of wine LAB are needed. In this work a simple and accurate protocol for identifying species of LAB isolated from grape must and wine is presented. This protocol is based on the amplification, directly from colony, of 16S rDNA and later digestion with one of the following restriction enzymes BfaI, MseI and AluI. A sequential use of the three enzymes is proposed to simplify LAB wine ide…
A real-time PCR assay for detection and quantification of 2-branched (1,3)-β-D–glucan producing lactic acid bacteria in cider
2010
28 p.-1 fig.-4 tab.
Which lactic acid bacteria are responsible for histamine production in wine?
2005
Aims: To quantify the ability of 136 lactic acid bacteria (LAB), isolated from wine, to produce histamine and to identify the bacteria responsible for histamine production in wine. Methods and Results: A qualitative method based on pH changes in a plate assay was used to detect wine strains capable of producing high levels of histamine. Two quantitative, highly sensitive methods were used, an enzymatic method and HPLC, to quantify the histamine produced by LAB. Finally, an improved PCR test was carried out to detect the presence of histidine decarboxylase gene in these bacteria. The species exhibiting the highest frequency of histamine production is Oenococcus oeni. However, the concentrati…