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Several Strains (several + strain)
Selected AbstractsGenetic heterogeneity and functional properties of intestinal bifidobacteriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2004J. Mättö Abstract Aims:, The aim of the present study was to compare several molecular methods for the identification and genotyping of bifidobacteria, and further to investigate genetic heterogeneity and functional properties of bifidobacterial isolates from intestinal samples of Finnish adult subjects. Methods and Results:, A total of 153 intestinal bifidobacterial isolates were included in initial screening and 34 isolates were further characterized. Identification results obtained with PCR,ELISA and ribotyping were well in accordance with each other, while randomly amplified polymorphic DNA (RAPD) gave tentative identification only to Bifidobacterium bifidum and to 65% of the B. longum isolates. The most commonly detected species were B. longum biotype longum followed by B. adolescentis and B. bifidum. In addition, B. animalis (lactis), B. angulatum and B. pseudocatenulatum were found. Ribotyping and pulsed-field gel electrophoresis (PFGE) proved to be discriminatory methods for bifidobacteria, but also RAPD revealed intraspecies heterogeneity. Besides two B. animalis (lactis) isolates with very close similarity to a commercially available probiotic strain, none of the intestinal isolates showed optimal survival in all tolerance (acid, bile and oxygen) or growth performance tests. Conclusions:, Several species/strains of bifidobacteria simultaneously colonize the gastrointestinal tract of healthy Finnish adults and intestinal Bifidobacterium isolates were genetically heterogeneous. Functional properties of bifidobacteria were strain-dependent. Significance and Impact of the Study:, Applicability of ribotyping with the automated RiboPrinter® System for identification and genotyping of bifidobacteria was shown in the present study. [source] Doppler Ultrasound in MiceECHOCARDIOGRAPHY, Issue 1 2007Jörg Stypmann Color, power, spectral, and tissue Doppler have been applied to mice. Due to the noninvasive nature of the technique, serial intraindividual Doppler measurements of cardiovascular function are feasible in wild-type and genetically altered mice before and after microsurgical procedures or to follow age-related changes. Fifty-megahertz ultrasound biomicroscopy allows to record the first beats of the embryonic mouse heart at somite stage 5, and the first Doppler-flow signals can be recorded after the onset of intrauterine cardiovascular function at somite stage 7. Using 10- to 20-MHz ultrasound transducers in the mouse embryo, cardiac, and circulatory function can be studied as early as 7.5 days after postcoital mucous plug. Postnatal Doppler ultrasound examinations in mice are possible from birth to senescent age. Several strain-, age-, and gender-related differences of Doppler ultrasound findings have been reported in mice. Results of Doppler examinations are influenced by the experimental settings as stress testing or different forms of anesthesia. This review summarizes the present status of Doppler ultrasound examinations in mice and animal handling in the framework of a comprehensive phenotype characterization of cardiac contractile and circulatory function. [source] Thermomyces lanuginosus: properties of strains and their hemicellulasesFEMS MICROBIOLOGY REVIEWS, Issue 1 2003Suren Singh Abstract The non-cellulolytic Thermomyces lanuginosus is a widespread and frequently isolated thermophilic fungus. Several strains of this fungus have been reported to produce high levels of cellulase-free ,-xylanase both in shake-flask and bioreactor cultivations but intraspecies variability in terms of ,-xylanase production is apparent. Furthermore all strains produce low extracellular levels of other hemicellulases involved in hemicellulose hydrolysis. Crude and purified hemicellulases from this fungus are stable at high temperatures in the range of 50,80°C and over a broad pH range (3,12). Various strains are reported to produce a single xylanase with molecular masses varying between 23 and 29 kDa and pI values between 3.7 and 4.1. The gene encoding the T. lanuginosus xylanase has been cloned and sequenced and is shown to be a member of family 11 glycosyl hydrolases. The crystal structure of the xylanase indicates that the enzyme consists of two ,-sheets and one ,-helix and forms a rigid complex with the three central sugars of xyloheptaose whereas the peripheral sugars might assume different configurations thereby allowing branched xylan chains to be accepted. The presence of an extra disulfide bridge between the ,-strand and the ,-helix, as well as to an increase in the density of charged residues throughout the xylanase might contribute to the thermostability. The ability of T. lanuginosus to produce high levels of cellulase-free thermostable xylanase has made the fungus an attractive source of thermostable xylanase with potential as a bleach-boosting agent in the pulp and paper industry and as an additive in the baking industry. [source] Detection and Identification of Brenneria nigrifluens, the Causal Agent of the Shallow Bark Canker of Walnut by, PCR AmplificationJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2008S. Loreti Abstract A 1 kb DNA band from strains of Brenneria nigrifluens, as shown by amplification of their genomic DNA by polymerase chain reaction (PCR) using minisatellite primer designed on the minisatellite sequence of the M13 phage, was isolated, cloned and sequenced. Specific oligonucleotides (F1,C3) were selected into this 1 kb DNA sequence and used in a PCR assay to detect and identify strains of B. nigrifluens. Several strains of B. nigrifluens were assessed with F1,C3 primers producing a specific band of approximately 250 bp pairs in length. This target was successfully amplified from purified genomic DNA, from bacterial culture and directly from infected walnut bark tissue. No amplification was obtained when the PCR assay was performed on other plant-pathogenic species from the following genera Brenneria, Erwinia, Agrobacterium, Pseudomonas, Ralstonia, Pectobacterium, Xanthomonas and from walnut-associated bacteria, indicating the specificity of these primers. The PCR assay with the primers described here provides a rapid, specific and sensitive diagnostic method for B. nigrifluens and a useful tool for epidemiological studies. [source] Functionality of lactic acid bacteria peptidase activities in the hydrolysis of gliadin-like fragmentsLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2008C.L. Gerez Abstract Aims:, To evaluate the role of the peptidase activities from sourdough lactic acid bacteria (LAB) in the degradation of ,-gliadin fragments. Methods and Results:, Different proline-containing substrates were hydrolysed by LAB indicating pro-specific peptidase activities. Lactobacillus plantarum CRL 775 and Pediococcus pentosaceus CRL 792 displayed the highest tri- and di-peptidase activities, respectively. Lactobacillus plantarum strains hydrolysed more than 60%,-gliadin fragments corresponding to the 31,43 and 62,75 amino acids in the protein after 2 h. None of the LAB strains alone could hydrolyse 57,89 ,-gliadin peptide; however, the combination of L. plantarum CRL 775 and P. pentosaceus CRL 792 led to hydrolysis (57%) of this peptide in 8 h. Conclusions:, The capacity of LAB strains to degrade ,-gliadin fragments was not correlated to individual peptidase activities. Several strains separately degraded the 31,43 and 62,75 ,-gliadin fragments, while the 57,89 peptide degradation was associated with the combination of peptidase profiles from pooled LAB strains. This is the first report on the peptide hydrolase system of sourdough pediococci and its ability to reduce ,-gliadin fragments. Significance and Impact of the Study:, This study contributes to a better knowledge of sourdough LAB proteolytic system and its role in the degradation of proline-rich ,-gliadin peptides involved in celiac disease. [source] Saccharomyces cerevisiae biodiversity in spontaneous commercial fermentations of grape musts with ,adequate' and ,inadequate' assimilable-nitrogen contentLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2003L. Granchi Abstract Aim: To evaluate whether intraspecific diversity of Saccharomyces cerevisiae in wine fermentations is affected by initial assimilable-nitrogen content. Methods and Results:Saccharomyces cerevisiae isolates from two spontaneous commercial wine fermentations started with adequate and inadequate nitrogen amounts were characterized by mitochondrial DNA restriction analysis. Several strains occurred in each fermentation, two strains, but not the same ones, being predominant at frequencies of about 30%. No significant differences were detected by comparing the biodiversity indices of the two fermentations. Cluster analysis demonstrated that the strain distribution was independent of nitrogen content, the two pairs of closely related dominant strains grouping into clusters at low similarity. Conclusions: The genetic variability of S. cerevisiae in wine fermentations seemed not to depend on the nitrogen availabilty in musts. Significance and Impact of the Study: Nitrogen content did not affect the genetic diversity but may have induced a ,selection effect' on S. cerevisiae strains dominating wine fermentations, with possible consequences on wine properties. [source] Elucidating the molecular mechanisms of bacterial virulence using non-mammalian hostsMOLECULAR MICROBIOLOGY, Issue 5 2000Shalina Mahajan-Miklos Several strains of the human opportunistic pathogen Pseudomonas aeruginosa infect plants, nematodes and insects. Our laboratory has developed a multihost pathogenesis system based on the P. aeruginosa clinical isolate PA14, in which non-mammalian hosts are used to screen directly for virulence-attenuated mutants. The majority of PA14 mutants isolated using non-mammalian hosts also displayed reduced virulence in a burned mouse model. Surprisingly, only a few host-specific virulence factors were identified, and many of the P. aeruginosa mutants were attenuated in virulence in all the hosts. These studies illustrate the extensive conservation in the virulence mechanisms used by P. aeruginosa to infect evolutionarily diverged hosts, and validate the multihost method of screening for virulence factors relevant to mammalian pathogenesis. Through the use of genetically tractable hosts, the multihost pathogenesis model also provides tools for elucidating host responses and dissecting the fundamental molecular interactions that underlie bacterial pathogenesis. [source] The Vibrio cholerae haemolysin anion channel is required for cell vacuolation and deathCELLULAR MICROBIOLOGY, Issue 7 2002Monica Moschioni Summary Several strains of Vibrio cholerae secrete a haemolytic toxin of 63 kDa, termed V. cholerae cytolysin (VCC). This toxin causes extensive vacuolation and death of cells in culture and forms an anion-selective channel in planar lipid bilayers and in cells. Here, we identify inhibitors of the VCC anion channel and show that the formation of the anion channel is necessary for the development of the vacuoles and for the cell death induced by this toxin. Using markers of cell organelles, we show that vacuoles derive from different intracellular compartments and we identify the contribution of late endosomes and of the trans -Golgi network in vacuole biogenesis. [source] Animal models of diabetes mellitusDIABETIC MEDICINE, Issue 4 2005D. A. Rees Abstract Animal models have been used extensively in diabetes research. Early studies used pancreatectomised dogs to confirm the central role of the pancreas in glucose homeostasis, culminating in the discovery and purification of insulin. Today, animal experimentation is contentious and subject to legal and ethical restrictions that vary throughout the world. Most experiments are carried out on rodents, although some studies are still performed on larger animals. Several toxins, including streptozotocin and alloxan, induce hyperglycaemia in rats and mice. Selective inbreeding has produced several strains of animal that are considered reasonable models of Type 1 diabetes, Type 2 diabetes and related phenotypes such as obesity and insulin resistance. Apart from their use in studying the pathogenesis of the disease and its complications, all new treatments for diabetes, including islet cell transplantation and preventative strategies, are initially investigated in animals. In recent years, molecular biological techniques have produced a large number of new animal models for the study of diabetes, including knock-in, generalized knock-out and tissue-specific knockout mice. [source] Chondrochloren A and B, New ,-Amino Styrenes from Chondromyces crocatus (Myxobacteria)EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2003Rolf Jansen Abstract In a screening for biologically active metabolites of the genus Chondromyces, two novel metabolites, chondrochloren A (1) and B (2), were isolated from several strains of C. crocatus. Compounds 1 and 2 are unique chloro-hydroxy-styryl amides of a highly modified C14 carboxylic acid, which comprises an unsaturated ketone, two hydroxy, two methoxy and three methyl groups. After assignment of the absolute configuration of both carbinol stereocenters by Mosher's method, NMR spectroscopic data combined with MM2 calculations allowed the prediction of the preferred conformation in solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] In vitro Study of the Antibacterial Activity of Bioactive Glass-ceramic Scaffolds,ADVANCED ENGINEERING MATERIALS, Issue 7 2009Marta F. Gorriti Staphylococcus aureus is an opportunistic pathogen of major clinical interest for its high prevalence in biomaterial-related infections. This experimental study provides the first evidence in vitro that bioactive glass-ceramic scaffolds made from both 45S5 Bioglass® and from boron containing bioactive glass (45S5.2B) as well as their ionic dissolution products do no exhibit antibacterial effect against several strains of S. aureus. [source] JET-SUSPENDED, CALCITE-BALLASTED CYANOBACTERIAL WATERWARTS IN A DESERT SPRING1JOURNAL OF PHYCOLOGY, Issue 3 2002Ferran Garcia-Pichel We describe a population of colonial cyanobacteria (waterwarts) that develops as the dominant primary producer in a bottom-fed, O2 -poor, warm spring in the Cuatro Ciénegas karstic region of the Mexican Chihuahuan Desert. The centimeter-sized waterwarts were suspended within a central, conically shaped, 6-m deep well by upwelling waters. Waterwarts were built by an Aphanothece -like unicellular cyanobacterium and supported a community of epiphytic filamentous cyanobacteria and diatoms but were free of heterotrophic bacteria inside. Sequence analysis of 16S rRNA genes revealed that this cyanobacterium is only distantly related to several strains of other unicellular cyanobacteria (Merismopedia, Cyanothece, Microcystis). Waterwarts contained orderly arrangements of mineral crystallites, made up of microcrystalline low-magnesium calcite with high levels of strontium and sulfur. Waterwarts were 95.9% (v/v) glycan, 2.8% cells, and 1.3% mineral grains and had a buoyant density of 1.034 kg·L,1. An analysis of the hydrological properties of the spring well and the waterwarts demonstrated that both large colony size and the presence of controlled amounts of mineral ballast are required to prevent the population from being washed out of the well. The unique hydrological characteristics of the spring have likely selected for both traits. The mechanisms by which controlled nucleation of extracellular calcite is achieved remain to be explored. [source] The Role of Acinetobacter baumannii as a Nosocomial Pathogen for Dogs and Cats in an Intensive Care UnitJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 2 2000Thierry Francey Acinetobacter baumannii is a nosocomial pathogen associated with high morbidity and mortality in humans. Whereas infections with strains of Acinetobacter species have been reported in various situations, the importance of A baumannii as a nosocomial pathogen in veterinary hospitals has not been studied so far. In this retrospective case series, we describe 17 dogs and 2 cats from which A baumannii had been isolated during a 21/2-year period. In 7 dogs, A baumannii induced systemic signs of illness, whereas 12 animals showed signs of local infection. In all animals with systemic infection, and in 2 with localized infection, A baumannii contributed to the death of the animal or contributed to euthanasia; the remaining 8 dogs and both cats recovered. Molecular typing of the isolates with restriction polymorphisms of ribosomal DNA provided evidence of nosocomial spread of this pathogen and for the presence of several strains of A baumannii in the hospital environment. [source] Multiple copies of cytochrome oxidase 1 in species of the fungal genus FusariumMOLECULAR ECOLOGY RESOURCES, Issue 2009SCOTT R. GILMORE Abstract Using data from published mitochondrial or complete genomes, we developed and tested primers for amplification and sequencing of the barcode region of cytochrome oxidase 1 (COX1) of the fungal genus Fusarium, related genera of the order Hypocreales, and degenerate primers for fungi in the subdivision Pezizomycotina. The primers were successful for amplifying and sequencing COX1 barcodes from 13 genera of Hypocreales (Acremonium, Beauveria, Clonostachys, Emericellopsis, Fusarium, Gliocladium, Hypocrea, Lanatonectria, Lecanicillium, Metarhizium, Monocillium, Neonectria and Stilbella), 22 taxa of Fusarium, and two genera in other orders (Arthrosporium, Monilochaetes). Parologous copies of COX1 occurred in several strains of Fusarium. In some, copies of the same length were detected either by heterozygous bases in otherwise clean sequences or in different replicates of amplification and sequencing events; this may indicate multiple transcribed copies. Other strains included one or two introns. Two intron insertion sites had at least two nonhomologous intron sequences among Fusarium species. Irrespective of whether the multiple copy issue could be resolved by sequencing RNA transcripts, developing a precise COX1 -based barcoding system for Fusarium may not be feasible. The overall divergence among homologous COX1 sequences obtained so far is rather low, with many species sharing identical sequences. [source] In vitro fermentability of human milk oligosaccharides by several strains of bifidobacteriaMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 11 2007Robert E. Ward Abstract This study was conducted to investigate the catabolism and fermentation of human milk oligosaccharides (HMO) by individual strains of bifidobacteria. Oligosaccharides were isolated from a pooled sample of human milk using solid-phase extraction, and then added to a growth medium as the sole source of fermentable carbohydrate. Of five strains of bifidobacteria tested (Bifidobacterium longum biovar infantis, Bifidobacterium bifidum, Bifidobacterium longum biovar longum, Bifidobacterium breve, and Bifidobacterium adolescentis), B. longum bv. infantis grew better, achieving triple the cell density then the other strains. B. bifidum did not reach a high cell density, yet generated free sialic acid, fucose and N-acetylglucosamine in the media, suggesting some capacity for HMO degradation. Thin layer chromatography profiles of spent fermentation broth suggests substantial degradation of oligosaccharides by B. longum bv. infantis, moderate degradation by B. bifidum and little degradation by other strains. While all strains were able to individually ferment two monosaccharide constituents of HMO, glucose and galactose, only B. longum bv. infantis and B. breve were able to ferment glucosamine, fucose and sialic acid. These results suggest that as a potential prebiotic, HMO may selectively promote the growth of certain bifidobacteria strains, and their catabolism may result in free monosaccharides in the colonic lumen. [source] Lack of evidence of endosymbiotic toxin-producing bacteria in clinical Rhizopus isolatesMYCOSES, Issue 3 2008Laila P. Partida-Martinez Summary Infections by Rhizopus spp. account for about 90% of zygomycoses, many of which are lethal in immunocompromised patients. We recently noted that several strains of Rhizopus microsporus harbour rare bacterial endosymbionts (Burkholderia sp.) for the production of ,mycotoxins', which might play a role as virulence factors in human Rhizopus infections. In this study eight clinical Rhizopus spp. isolates have been investigated for the presence of toxin-producing bacterial endosymbionts. By metabolomic data, PCR targeting bacterial 16S rDNA and microscopic investigations with fluorescence dyes we provide three lines of evidence showing that the fungal strains are not associated with endofungal bacteria. Consequently, toxin-producing bacteria are not essential for Rhizopus infections and the development of zygomycoses in humans. [source] Molecular epidemiology of rubella virus in Asia: Utility for reduction in the burden of diseases due to congenital rubella syndromePEDIATRICS INTERNATIONAL, Issue 2 2004Shigetaka Katow AbstractBackground:,Rubella is a mild disease mainly of infants, involving a rash and a fever. However, when women who have no immunity to rubella are infected during the early stage of pregnancy, their babies are often born with congenital rubella syndrome (CRS), which is characterized by a few disorders including deafness, cataracts and heart malformations. To prevent CRS, several strains of live attenuated rubella vaccine have been developed and introduced into immunization programs in many countries. In most Asian countries except Japan, Singapore and Taiwan, rubella remains uncontrolled, and the burden of diseases from CRS is high. In order to develop a control program to reduce the number of CRS cases in Asian countries, it is necessary to conduct a survey of rubella and CRS cases, and to then determine the genotype of the circulating rubella virus in each country. Methods:,Cases of rubella and CRS, based on national reporting systems or active surveillance in the Asian countries, are summarized. Sequences of the E1 gene of the virus isolates from the Asian countries were compared by phylogenic analysis. Results:,Recent studies of the molecular epidemiology of rubella virus worldwide revealed that there are two genotypes, and that genotype I is circulating almost worldwide, while genotype II is an Asian prototype restricted to the Asian continent. Genotype I viruses fall into a number of groups, some of which are geographically localized. Antigenically these two genotypes are cross-reactive and immunization with either virus results in immunity to all rubella viruses. Discussion:,The hypotheses that rubella virus has evolved on the Asian continent is proposed. The World Health Organization (WHO) has recognized that a rubella immunization program can be combined with the measles immuization program. Inclusion of rubella in the expanded program of immunization (EPI) of measles would be ideal in Asian countries, as it would be efficient and cost effective to administer one injection containing a three-combined vaccine (MMR). It would also be desirable given that WHO require laboratory tests to confirm the presence of measles or rubella as part of it's measles control project, because rubella is often misdiagnosed as measles. [source] | |||||||||||||||||||||||||