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Studied Strains (studied + strain)
Selected AbstractsCharacterization of yeast strains by fluorescence lifetime imaging microscopyFEMS YEAST RESEARCH, Issue 1 2008Hemant Bhatta Abstract The results of fluorescence lifetime imaging microscopy of selected yeast strains were presented and the fact that the lifetime distributions can be successfully used for strain characterization and differentiation was demonstrated. Four strains of industrially relevant yeast Saccharomyces were excited at 405 nm and the autofluorescence observed within 440,540 nm. Using statistical tools such as empirical cumulative distribution functions with Kolmogorov,Smirnov testing, the four studied strains were categorized into three different groups for normal sample size of 70 cells slide,1 at a significance level of 5%. The differentiation of all of the examined strains from one another was shown to be possible by increasing the sample size to 420 cells, which is achievable by taking the lifetime data at six different positions in the slide. [source] Difference between the spore sizes of Bacillus anthracis and other Bacillus speciesJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2007M. Carrera Abstract Aims:, To determine the size distribution of the spores of Bacillus anthracis, and compare its size with other Bacillus species grown and sporulated under similar conditions. Methods and Results:, Spores from several Bacillus species, including seven strains of B. anthracis and six close neighbours, were prepared and studied using identical media, protocols and instruments. Here, we report the spore length and diameter distributions, as determined by transmission electron microscopy (TEM). We calculated the aspect ratio and volume of each spore. All the studied strains of B. anthracis had similar diameter (mean range between 0·81 ± 0·08 ,m and 0·86 ± 0·08 ,m). The mean lengths of the spores from different B. anthracis strains fell into two significantly different groups: one with mean spore lengths 1·26 ± 0·13 ,m or shorter, and another group of strains with mean spore lengths between 1·49 and 1·67 ,m. The strains of B. anthracis that were significantly shorter also sporulated with higher yield at relatively lower temperature. The grouping of B. anthracis strains by size and sporulation temperature did not correlate with their respective virulence. Conclusions:, The spores of Bacillus subtilis and Bacillus atrophaeus (previously named Bacillus globigii), two commonly used simulants of B. anthracis, were considerably smaller in length, diameter and volume than all the B. anthracis spores studied. Although rarely used as simulants, the spores of Bacillus cereus and Bacillus thuringiensis had dimensions similar to those of B. anthracis. Significance and Impact of the Study:, Spores of nonvirulent Bacillus species are often used as simulants in the development and testing of countermeasures for biodefence against B. anthracis. The data presented here should help in the selection of simulants that better resemble the properties of B. anthracis, and thus, more accurately represent the performance of collectors, detectors and other countermeasures against this threat agent. [source] Adhesion of Staphylococcus aureus and Staphylococcus epidermidis to the Episkin® reconstructed epidermis model and to an inert 304 stainless steel substrateJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2004G. Lerebour Abstract Aims:, The aim of this study was to evaluate the respective influence of the physicochemical interactions and the roughness involved in the first part of the biological substrate biocontamination. Methods and Results:, Therefore we compared the bioadhesion results obtained on the biological model substrate (Episkin®) and on a commonly employed inert substrate (AISI 304 stainless steel), frequently used either in dermatology or in development of medical devices. The two studied strains presented different characteristics, both physicochemical and microbiological. Staphylococcus epidermidis, a relatively hydrophobic bacteria capable of exchanging interactions which are principally of the van der Waals type, adhered more to 304 steel than to the surface of reconstituted skin. As for S. aureus, an essentially basic, hydrophilic bacteria, was more adherent to Episkin® (a bipolar, hydrophilic substrate) than to stainless steel (a unipolar, basic, hydrophilic substrate). Conclusions:, In the absence of electrostatic interactions, the adhesion of substrate-dependent bacteria to the surface of reconstituted skin was dependent upon the balance between ,LW, ,+ and ,,. Significance and Impact of the Study:, Consequently, so as to restrict microbial adhesion and reduce adhesive binding between micro-organisms and the surface of the skin, it would be preferable to render this substrate hydrophobic and apolar through the use of appropriate surface treatment. [source] Resistance to oxidative stress caused by ceftazidime and piperacillin in a bio,lm of PseudomonasLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 5 2004Paola C. Battán Abstract The capacity to form a bio,lm was evaluated in Pseudomonas aeruginosa isolated from patients with lung and urinary infections. Adherence, development of microcolonies and slime formation varied in the studied strains. P. aeruginosa P63 isolated from cystic ,brosis (CF) exhibited important microcolony formation with the densest bio,lm, and was selected to study the oxidative stress produced with ceftazidime and piperacillin by means of chemiluminescence (CL) in cell suspensions and bio,lm. P. aeruginosa strain P63 was compared with P69; both were sensitive to ceftazidime and showed increase of reactive species of oxygen (ROS) in the presence of this antibiotic. P. aeruginosas P69 exhibited resistance to piperacillin and low ROS production, while piperacillin-sensitive strain P63 showed high oxidative stress with this antibiotic. Piperacillin stimulated oxidative stress, increasing ROS production only in the sensitive strain. Higher antibiotic concentrations were necessary to augment ROS in bacteria bio,lm than in suspension. Incubation of P63 strain with ceftazidime or piperacillin in the presence of its own extracellular matrix (EM) or sodium alginate stimulated lesser oxidative stress and slower decrease of ROS than in the absence of these polysaccharides. A variant, V10, obtained from strain P63 showed more sensitivity to the antibiotics than the wild-type, and concomitantly exhibited higher production of ROS in the presence of both the antibiotics studied. Copyright © 2004 John Wiley & Sons, Ltd. [source] Probiotics and health: a review of the evidenceNUTRITION BULLETIN, Issue 4 2009E. Weichselbaum Summary Probiotics are live microorganisms , mainly bacteria , which when administered in adequate amounts confer a health benefit on the host. There is rising interest in this area, but reports in the media are often conflicting. The aim of this review is to consider the current evidence on the effects of probiotics on health, focusing on gut-related health issues and the immune system, with the objective to provide a clearer picture of whether and how probiotics can be beneficial for health. The outcomes of this review are based on more than 100 original studies, meta-analyses and systematic reviews. A variety of different strains have been used in studies on probiotics, and it is important to remember that the effectiveness of probiotics is strain-specific, which means that each single probiotic strain has to be tested to assess its potential health benefits. Overall, despite the diversity of strains used in the studies included in this review, there is evidence that probiotics have the potential to be beneficial for our health. Studies in patients with inflammatory bowel disease show probiotic strains to be able to decrease the recurrence of ulcerative colitis and occurrence and recurrence of pouchitis, however, current evidence suggests that probiotics are ineffective in treating patients with Crohn's disease. Patients with irritable bowel syndrome show a reduction in symptoms when treated with selected probiotic strains, but high placebo effects have been reported as well. The evidence of the efficacy of probiotics in patients suffering from constipation is limited, but the evidence seems promising for some strains to bring relief to patients suffering from constipation. There is good evidence that a number of probiotic strains are effective in preventing antibiotic-associated diarrhoea. The most commonly studied strains are Lactobacillus rhamnosus GG (LGG) and Saccharomyces boulardii, but other strains and mixtures of strains seem to be effective as well. There is also promising evidence of a preventive effect of probiotics in Clostridium difficile -associated diarrhoea, although some studies have been too small to obtain statistically significant findings. The effect of probiotics in acute diarrhoea, particularly in children, is well studied. Selected probiotic strains seem to be effective in reducing the duration of acute diarrhoea. LGG and S. boulardii are again the most commonly used strains and a number of studies have shown them to be effective, although one meta-analysis showed that the effect of LGG was only significant in children in Western countries, not in children in developing countries, which may be due to different causes of diarrhoea in these regions. Studies investigating the preventive effect of probiotics in the context of common cold and flu infections show that the studied strains failed to lower the incidence of episodes but that they have the potential to decrease the duration of episodes, which suggests that the immune system may be more efficient in fighting off common cold and flu infections after consuming these strains. The evidence so far does not suggest that probiotics are effective in preventing or treating allergies or in treating eczema. However, some probiotic strains seem to lower the risk of developing eczema if taken by pregnant women and their infants in early life. [source] Comparative QSAR Studies on Toxicity of Phenol Derivatives Using Quantum Topological Molecular Similarity IndicesCHEMICAL BIOLOGY & DRUG DESIGN, Issue 5 2010Bahram Hemmateenejad Quantitative structure activity relationship (QSAR) analyses using a novel type of electronic descriptors called quantum topological molecular similarity (QTMS) indices were operated to describe and compare the mechanisms of toxicity of phenols toward five different strains (i.e., Tetrahymena pyriformis, L1210 Leukemia, Pseudomonas putida, Raja japonica and Cucumis sativus). The appropriate QSAR models for the toxicity data were obtained separately employing partial least squares (PLS) regression combined with genetic algorithms (GA), as a variable selection method. The resulting QSAR models were used to identify molecular fragments of phenol derivatives whose electronic properties contribute significantly to the observed toxicities. Using this information, it was feasible to discriminate between the mechanisms of action of phenol toxicity to the studied strains. It was found that toxicities of phenols to all strains, except with L1210 Leukemia, are significantly affected by electronic features of the phenolic hydroxyl group (C-O-H). Meanwhile, the resulting models can describe the inductive and resonance effects of substituents on various toxicities. [source] Differential immunomodulatory properties of Bifidobacterium logum strains: relevance to probiotic selection and clinical applicationsCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2007M. Medina Summary Modulation of host immunity is one of the proposed benefits of the consumption of probiotics. Nonetheless, comparative studies on the immunological properties that support the selection of strains of the same species for specific health benefits are limited. In this study, the ability of different strains of Bifidobacterium longum to induce cytokine production by peripheral blood mononuclear cells (PBMCs) has been evaluated. Live cells of all B. longum strains greatly stimulated regulatory cytokine interleukin (IL)-10 and proinflammatory cytokine tumour necrosis factor (TNF)-, production. Strains of the same species also induced specific cytokine patterns, suggesting that they could drive immune responses in different directions. The probiotic strain B. longum W11 stimulated strongly the production of T helper 1 (Th1) cytokines while B. longum NCIMB 8809 and BIF53 induced low levels of Th1 cytokines and high levels of IL-10. The effects of cell-surface components obtained by sonication of B. longum strains overall confirm the effects detected by stimulation of PBMCs with live cells, indicating that these components are important determinants of the immunomodulatory activity of B. longum. Genomic DNA of some strains stimulated the production of the Th1 and pro-inflammatory cytokines, interferon (IFN)-, and TNF-,, but not that of IL-10. None of the cell-free culture supernatants of the studied strains was able to induce TNF-, production, suggesting that the proinflammatory component of these strains is associated mainly with structural cell molecules. The results suggest that despite sharing certain features, some strains can perform a better functional role than others and their careful selection for therapeutic use is desirable. [source] | |||||||||||||