Search results for "bacteria."
showing 10 items of 4757 documents
NovelAmycolatopsis balhimycinabiochemical abilities unveiled by proteomics
2014
Amycolatopsis balhimycina DSM5908 is an actinomycete producer of balhimycin, an analogue of vancomycin, the antibiotic of ‘last resort’ against multidrug-resistant Gram-positive pathogens. Most knowledge on glycopeptide biosynthetic pathways comes from studies on A. balhimycina as this strain, among glycopeptide producers, is genetically more amenable. The recent availability of its genome sequence allowed to perform differential proteomic analyses elucidating key metabolic pathways leading to antibiotic production in different growth conditions. To implement proteomic data on A. balhimycina derived from 2-DE approaches and to identify novel components, a combined approach based on protein …
Deciphering the role of insertion sequences in the evolution of bacterial epidemic pathogens with panISa software
2020
Next-generation sequencing (NGS) is now widely used in microbiology to explore genome evolution and the structure of pathogen outbreaks. Bioinformatics pipelines readily detect single-nucleotide polymorphisms or short indels. However, bacterial genomes also evolve through the action of small transposable elements called insertion sequences (ISs), which are difficult to detect due to their short length and multiple repetitions throughout the genome. We designed panISa software for the ab initio detection of IS insertions in the genomes of prokaryotes. PanISa has been released as open source software (GPL3) available from https://github.com/bvalot/panISa. In this study, we assessed the utilit…
ACELLULAR PERTUSSIS VACCINE COMPOSED OF GENETICALLY INACTIVATED PERTUSSIS TOXIN: SAFETY AND IMMUNOGENICITY IN 12- TO 24- AND 2-TO 4-MONTH-OLD CHILDREN
1992
To determine whether a nontoxic derivative of pertussis toxin obtained by recombinant DNA technology, PT-9K/129G, is a good candidate for a new pertussis vaccine, we examined the safety and the immunogenicity in children of a vaccine containing 15 micrograms of PT-9K/129G protein and 0.5 mg of aluminum hydroxide per dose. Fifty-three children 12 to 24 months of age and 21 infants aged 2 to 4 months were injected with two and three doses, respectively. The vaccine did not induce significant local or systemic reactions and elicited an increase of antibody titer in more than 98% of the children. The geometric mean of the toxin-neutralizing titers increased after each dose and was 85 units in c…
Fast identification of wine related lactic acid bacteria by multiplex PCR
2013
The microflora of must and wine consists of yeasts, acetic acid bacteria and lactic acid bacteria (LAB). The latter group plays an important role for wine quality. The malolactic fermentation carried out by LAB leads to deacidification and stabilisation of wines. Nevertheless, LAB are often associated with wine spoilage. They are mainly responsible for the formation of biogenic amines. Furthermore, some strains produce exopolysaccharide slimes, acetic acid, diacetyl and other off-flavours. In this context a better monitoring of the vinification process is crucial to improve wine quality. Moreover, a lot of biodiversity studies would also profit from a fast and reliable identification method…
The potential of positively-charged cellulose sponge for malolactic fermentation of wine, using Oenococcus oeni
2001
Malolactic fermentation (MLF) is a secondary bioconversion developed in some wines involving malic acid decarboxylation. The induction of MLF in wine by cultures of free and immobilized Oenococcus oeni cells was investigated. This work reports on the effect of surface charges in the immobilization material, a recently described fibrous sponge, as well as the pH and the composition of the media where cells are suspended. A chemical treatment provided positive charge to the sponges (DE or DEAE) and gave the highest cell loadings and subsequent resistance to removal. Preculture media to grow the malolactic bacteria before the immobilization procedure were also evaluated. We have established fa…
Induction of stress proteins inLeuconostoc oenos to perform direct inoculation of wine
1994
The enhancement or induction of the protein synthesis was clearly observed in cells ofL. oenos labeled with35S for five proteins during heat shock at 42°C and acid shock at pH 3. Furthermore, no stress protein was induced after exposure ofL. oenos to ethanol shock 10% (v/v). Moreover, survival ofL. oenos in wine and ability to perform alolactic fermentation was improved after direct inoculation when cells were pretreated at 42°C.
Amino acids and volatile compounds in wines from Cabernet Sauvignon and Tempranillo varieties subjected to malolactic fermentation in barrels
2012
The aim of the present paper is to compare the behaviour of industrial lactic bacteria and indigenous bacteria of the cellar when malolactic fermentation was carried out in barrels. The effects of these bacteria on the concentration of metabolised amino acids during malolactic fermentation and on the composition of volatile compounds both before and after malolactic fermentation are studied. The experiment was performed with wines of the Tempranillo and Cabernet Sauvignon varieties. An analysis has been made of the easily extractable volatile compounds of the wood and the compounds from the grapes, and the action of the yeasts during the alcoholic fermentation. Acetoin and diacetyl decreas…
Maintenance of Wine-Associated Microorganisms
2008
A great variety of microorganisms growing on grapes, in must, or in wine have been isolated, which also have an influence on wine quality. They belong to acidtolerant microorganisms such as lactic acid bacteria, acetic acid bacteria, and yeasts. On grapes also molds can be found. The most important species for conversion of must into wine are the yeast Saccharomyces cerevisiae and the lactic acid bacterium Oenococcus oeni, which perform alcoholic and malolactic fermentation, respectively. Both species are used as starter cultures. A variety of techniques and media are available for the enrichment, culture, and preservation of these microorganisms. For selected species culture and preservati…
Microbiological and chemical monitoring of Marsala base wine obtained by spontaneous fermentation during large-scale production
2014
The present work was undertaken to evaluate the effect of natural wine making on the microbial and chemical composition of Marsala base wine. To this purpose, a large-scale vinification process of Grillo grape cultivar was monitored from the grape harvest to the final product. Total yeasts (TY) showed a rapid increase after must pressings and reached values that were almost identical to those registered during conventional wine makings. Lactic acid bacteria (LAB) were registered at the highest levels simultaneous to those of yeast growth at the beginning of the process. Saccharomyces cerevisiae was the species found at the highest concentrations in all samples analysed. Several strains (n =…
Typical metabolic traits of two Oenococcus oeni strains isolated from Valpolicella wines
2004
Aims: Physiological comparison of two indigenous Oenococcus oeni strains, U1 and F3 isolated in the same area (Valpolicella, Italy) in order to select a performant starter for MLF in wine. Methods and Results: Growth rate, sugar and malate metabolism in FT80 media at pH 5·3 and 3·5 were analysed. The amount of total protein synthesized and the level of expression of the small Hsp Lo18 were evaluated by radiolabelling and immunodetection experiments after heat (42°C), acid (pH 3·5) and ethanol (12% v/v) stresses. Strain U1 showed significantly lower specific growth rate and growth yield in acid conditions than strain F3. However, strain U1 had a higher malate consumption capacity at pH 3·5…