Search results for "Gram-Positive Cocci"
showing 10 items of 20 documents
Acid sensitivity of neomycin-resistant mutants ofOenococcus oeni: a relationship between reduction of ATPase activity and lack of malolactic activity
1999
Mutants of Oenococcus oeni were isolated as spontaneous neomycin-resistant mutants. Three of these mutants harbored a significantly reduced ATPase activity that represented 50% of that of the wild-type strain. Their growth rates were also impaired at pH 5.3 (46-86% of the wild-type level). However, the profiles of sugar consumption appeared identical to those of the parental strain. At pH 3.2, all the mutant strains failed to grow and a drastic decrease in viability was observed after an acid shock. Surprisingly, all the isolated mutants were devoid of malolactic activity. These results suggest that the ATPase and malolactic activities of O. oeni are linked to each other and play a crucial …
Bacteremia after diagnostic conventional laparoscopy and minilaparoscopy: a prospective study in 100 patients.
2006
Background/Goals: Diagnostic laparoscopy under sedoanalgesia is a valuable tool in the work-up of liver diseases and is helpful as a staging procedure. The rate of bacteremia caused by this procedure is unknown, in particular when performed as minilaparoscopy. Study: A 100 consecutive patients having undergone diagnostic laparoscopy carried out either conventionally (group I, n = 50) or as minilaparoscopy (group II, n - 50) were prospectively enrolled in this study. Blood cultures were drawn before and within 5 minutes after the procedure. Risk factors for bacteremia were evaluated. Results: Bacterial growth occurred in 4 blood cultures drawn immediately after laparoscopy. No patient develo…
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…
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…
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…
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…
Comparison of two methods skipping cell lysis and protein extraction for identification of bacteria from blood cultures by matrix-assisted laser deso…
2019
ABSTRACT Objective Matrix-assisted laser desorption/ionization time-of-flight mass-spectrometry (MALDI-TOF MS) is widely used for fast identification of bacteria from blood cultures (BC). We compared the performance of two procedures, one including a pre-enrichment step in brain heart infusion and the other a direct method using vacutainer separator gel tubes (DI), for identification of bacteria from blood cultures by MALDI-TOF MS. Material and methods We first prepared a training set of 20 simulated bacteremia specimens, including 10 Gram-negative and 10 Gram-positive species. A total of 145 non-consecutive BCs flagged as positive (68 Gram-negative rods, and 77 Gram-positive cocci) were pr…