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Liquid Media (liquid + media)
Selected AbstractsApplication of Exchangeable Biochemical Reactors with Oxidase-Catalase-Co-immobilizates and Immobilized Microorganisms in a Microfluidic Chip-CalorimeterENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2008M. Leifheit Abstract Several methods for the quantitative detection of different compounds, e.g., L -amino acids, sugars or alcohols in liquid media were developed by application of an automatic measuring unit including a fluid chip-calorimeter FCC-21. For this purpose, enzymes were immobilized covalently on the inner and outer surface of CPG (controlled porous glass)-spherules with an outer diameter of 100,,m and filled into a micro flow-through reaction chamber (VR = 20,,L). The design of the measuring cell allows for easy insertion into the calorimeter device of a stored series of comfortably pre-fabricated measuring cells. These cells can be filled with different enzyme immobilizates. Different oxidases were used and co-immobilized with catalase for the improvement of the detection sensitivity. A signal amplification could be achieved up to a factor of 3.5 with this configuration. ,- D -glucose, ethanol and L -lysine could be detected in a range of 0.25,1.75,mM using glucose oxidase, alcohol oxidase and lysine oxidase. The group of oxidases in combination with the enzymatic catalysis of the intermediate H2O2 allows the quantitative detection of a large number of analytes. A good measurement and storage stability could be achieved for several weeks by this immobilization method. In addition to enzyme-based detection reactions, it was shown that living microorganisms can be immobilized in the reaction chamber. Thus, the system can be used as a whole-cell biosensor. The quantitative detection of phenol in the range of 10,100,,M could be performed using the actinomycete Rhodococcus sp. immobilized on glass beads by means of embedding into polymers. [source] Effect of thorium on the growth and capsule morphology of BradyrhizobiumENVIRONMENTAL MICROBIOLOGY, Issue 10 2003Mónica Santamaría Summary The thorium effect on Bradyrhizobium growth was assayed in liquid media. Th4+ inhibited the growth of Bradyrhizobium (Chamaecytisus) BGA-1, but this effect decreased in the presence of suspensions of live or dead bacterial cells. Th4+ induced the formation of a gel-like precipitate when added to a dense suspension of B. (Chamaecytisus) BGA-1 cells. Viable Bradyrhizobium cells remained in suspension after precipitate formation. Thorium was recovered in the precipitate, in which polysaccharide, lipopolysaccharide and proteins were also found. After Th4+ addition, the morphology of B. (Chamaecytisus) BGA-1 or Bradyrhizobium japonicum USDA 110 sedimented cells studied by scanning electron microscopy changed from an entangled network of capsulated bacteria to uncapsulated individual cells and an amorphous precipitate. Energy-dispersive X-ray spectroscopy showed that thorium was mainly in the amorphous fraction. Precipitate was also formed between B. (Chamaecytisus) BGA-1 and Al3+, which was also toxic to this bacterium. Precipitate induced by Th4+ or Al3+ was found in all Bradyrhizobium and Sinorhizobium strains tested, but not in Rhizobium, Salmonella typhimurium, Aerobacter aerogenes or Escherichia coli. These results suggest a specific defence mechanism based on metal precipitation by extracellular polymers. [source] Role of ethylenediaminetetraacetic acid on lead uptake and translocation by tumbleweed (Salsola kali L.)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2007Guadalupe de la Rosa Abstract Tumbleweed plants (Salsola kali L.) grown in agar and liquid media demonstrated a high capacity to accumulate Pb in their different parts without affecting biomass. Whereas shoot elongation and biomass were not significantly affected by high tissue concentrations of Pb, root growth was significantly affected relative to controls. Roots, stems, and leaves demonstrated Pb concentrations of 31,000, 5,500, and 2,100 mg/kg dry weight, respectively, when plants were grown in the agar medium containing 80 mg Pb/L. Application of ethylenediaminetetraacetic acid (EDTA) to Pb-contaminated media dramatically reduced the total acquisition of Pb from both types of media. However, EDTA significantly increased the translocation of Pb from roots to the aerial parts, as evidenced by a multifold increase (23- and 155-fold for agar and liquid media, respectively) in the translocation concentration factor. The concentration of the antioxidant thiol compounds significantly increased (p < 0.05) in plants grown with uncomplexed Pb treatments relative to control plants. Scanning-electron microscopy and electron dispersive x-ray spectroscopic evaluation of leaf samples demonstrated an interesting pattern of Pb translocation in the presence or absence of EDTA. Large Pb crystals were found across the leaf tissues (palisade, spongy parenchyma, and conducting tissues) in the absence of EDTA. Lead nanoparticles also were seen when plants were grown in Pb-EDTA solution. Ultramicroscopic features of tumbleweed provide clear evidence for the unrestricted conduction of Pb from the root to the aerial parts, and this property makes the plant a good candidate for phytoremediation. [source] Cell surface analysis of the lipid-discharging obligate hydrocarbonoclastic species of the genus AlcanivoraxEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 6 2010Alvin Brian Lange Abstract This study presents novel information useful for addressing the question how species of the genus Alcanivorax discharge triacylglycerols (TAG) and/or wax esters (WE). The observed structures were referred as "blebs" according to Gauthier et al.1 to avoid confusion with other discharging phenomena. The cells were aerobically cultivated on solid media and not in liquid media to maintain the cells in the native state, and were investigated by transmission electron microscopic (TEM) and scanning electron microscopic (SEM) methods to document the surface structures of the cells. The phenomenon of lipid export could be allocated to three phases: phase I: protrusion formation of the cell membrane occurred; phase II: discharging progressed further with blebs becoming larger; and phase III: the blebs at the cell surface were separated from the cells. Using freeze-fracture micrographs by TEM, vesicle experiments and TLC, we have shown that the blebs contained TAGs and WEs. The results shown in this study will support further research to unravel the unknown discharging mechanism. In addition, the formation of an extensive extracellular matrix was observed by SEM. [source] Relevance of incubation temperature for Vibrio salmonicida vaccine productionJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2002D.J. Colquhoun Aims:,To investigate the relationships between water temperature, bacterial growth, virulence and antigen expression in Vibrio salmonicida, the causal agent of cold water vibriosis in Atlantic salmon (Salmo salar L.). Methods and Results:,The significance of sea temperature was investigated using historical clinical and oceanographic data. An upper threshold for disease of approx. 10°C was established. The effects of culture temperature and media type on bacterial growth were studied on solid and in liquid media. The highest rates of cell division were identified at 15°C on solid media and 10°C in liquid media. Outer membrane protein (OMP) expression and serological response in Atlantic salmon were studied using sodium dodecyl sulphate-polyacrylamide gel electrophoresis, Western blotting and enzyme-linked immunosorbent assay. A novel 76-kDa OMP produced in unshaken cultures at 10°C was not found to stimulate a specific humoral response. Conclusions:,Diagnostic agar plate-based incubation of suspected V. salmonicida should be carried out at 15°C. High yield broth cultures for vaccine production should be incubated at 10°C or lower. Significance and Impact of the Study:,This study is, to the best of our knowledge, the first to identify different optimal temperatures in a bacterial species cultured on physically different types of media. The evidence presented suggests that V. salmonicida and possibly other bacteria destined for vaccine use in poikilothermic organisms should be cultured at temperatures consistent with that at which disease occurs. [source] Enhancement of activity and selectivity in lipase-catalyzed transesterification in ionic liquids by the use of additivesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2007Francisco J Hernández-Fernández Abstract BACKGROUND: Seven ionic liquids (ILs) based on 1-alkyl-3-methylimidazolium cation in combination with hexafluorophosphate and bis{(trifluoromethyl)sulfonyl}imide anions were tested as reaction media for lipase-catalyzed transesterification in low water conditions. With the aim of improving the activity and/or selectivity of the lipase, various treatments were applied to ionic liquid media such as equilibration with aqueous solutions of salts, NaHCO3 or Na2CO3, or the addition of a catalytic amount of a non-reactive organic base to the reaction mixture, triethylamine. RESULTS: The treated ionic liquids were shown to be excellent media for lipase-catalyzed ester synthesis by transesterification compared with conventional organic solvents, such as n -hexane. All treatments were found to enhance the synthetic activity of the enzyme, the best results being achieved with the addition of triethylamine. The addition of a catalytic amount of this base to the ILs resulted in a significant increase in both the synthetic activity and selectivity values. For instance, the synthetic activity in [emim+][TfN2,] was enhanced more than 12 times and the selectivity increased from 86% to 95% when triethylamine was used. CONCLUSION: These treatments could be easy-to-use approaches to improve the efficiency of enzymatic reactions in ionic liquids when the reaction does not proceed smoothly. Copyright © 2007 Society of Chemical Industry [source] Measurement of mass transfer coefficient in an airlift reactor with internal loop using coalescent and non-coalescent liquid mediaJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2004M Bla Abstract In this work the sulfite oxidation (SOM), dynamic pressure-step (DPM) and gassing-out (GOM) methods were compared for volumetric mass transfer coefficient measurement in an airlift reactor with internal loop. As a liquid phase both, non-coalescent and coalescent media were used. Among the methods discussed here, the mass transfer coefficient (kLa) values obtained by the DPM appear as the most reliable as they were found to be independent of oxygen concentration in the inlet gas, which confirmed the physical correctness of this method. The difference between data measured using air and oxygen was not higher than 10%, which was comparable to the scatter of experimental data. It has been found that the sulfite oxidation method yielded kLa values only a little higher than those obtained by the DPM and the difference did not exceed 10%. Up to an inlet gas velocity (UGC) of ,0.03 m s,1 the GOM using oxygen as a gas medium gave kLa values in fact identical with those obtained by the DPM. At higher flows of the inlet gas, the GOM yielded kLa values as much as 15% lower. The enhancement in oxygen mass transfer rate determined in non-coalescent media was estimated to be up to +15%, when compared with a coalescent batch. The experimental dependence of kLa vs the overall gas hold-up was described by an empirical correlation.1 Copyright © 2004 Society of Chemical Industry [source] ANTIBACTERIAL ACTIVITY AND BINDING ABILITY OF BOVINE LACTOFERRIN AGAINST PSEUDOMONAS SPP.JOURNAL OF FOOD SAFETY, Issue 1 2008WOAN-SUB KIM ABSTRACT The antibacterial activity of bovine lactoferrin was tested against Pseudomonas fluorescens and Pseudomonas syringae. The activity was studied by monitoring the growth of a Pseudomonas spp. in the presence or absence of bovine apo-lactoferrin, bovine holo-lactoferrin or native-lactoferrin in liquid media at different concentrations. Lactoferrin-binding proteins in the membrane fractions of Pseudomonas spp. were detected using far-Western blot analysis. The addition of bovine lactoferrin to the medium inhibited the growth of all tested strains. Furthermore, the growth of P. fluorescens and P. syringae was strongly inhibited by bovine apo-lactoferrin. The estimated molecular weights of lactoferrin-binding proteins in P. fluorescens were 70, 49, 47 and 25 kDa, and 70, 48 and 28 kDa in P. syringae. PRACTICAL APPLICATIONS Pseudomonas fluorescens is an important psychrotrophic bacterium responsible for undesirable flavors in milk and dairy products. Thus, flavor and texture defects, such as bitterness and running paste, were also reported. In addition, Pseudomonas syringae causes various diseases on many different susceptible plant species, generally producing chlorotic and necrotic lesions on leaves and fruits. The resultant bacterial spoilage causes considerable economic losses for the food and dairy industries. At present, antiseptics and agricultural chemicals are used for defense of foods and vegetables from these bacteria, but such substances are known to deleteriously affect the human body. The results of this study demonstrate that bovine lactoferrin significantly inhibits the growth of P. fluorescens and P. syringae. The results indicate that the incorporation of bovine lactoferrin is expected to protect dairy products, food and fruits from pathogenic bacteria. [source] Cultural Characterization and Conidial Dimorphism in Colletotrichum sublineolumJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2003E. A. Souza-Paccola Abstract Anthracnose, caused by Colletotrichum sublineolum, is one of the most important diseases of sorghum in Brazil. This fungus showed conidial dimorphism when cultivated on solid or in liquid media. In solid media only falcate conidia were produced, whereas in liquid media the conidia were of variable size, but mostly oval. Wild strains, differentiated by their , and , esterase electrophoretic profiles, were assessed. The effect of different culture media on the production of both conidial types was evaluated. Unlike that of oval conidia, the production of falcate conidia was light-dependent. Some strains failed to produce falcate conidia in solid media, but all produced oval conidia in all the liquid media. The falcate conidia were uninucleate, but oval conidia contained one to three nuclei, although most were uninucleate. Both types of conidia induced symptoms in inoculable sorghum plants under controlled conditions. Both oval and falcate conidia produced mutants after exposure to UV light, and hyphal anastomoses occurred in crosses between mutant conidia carriers of complementary markers. The production of these oval conidia in C. sublineolum is an alternative to pathogenicity tests and genetic studies, especially for strains that sporulate poorly in solid culture media. [source] Highly fluorinated compounds induce phase separation in, and nanostructuration of liquid media.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2006Possible impact on, use in chemical reactivity control Abstract Liquid perfluorocarbons-like supercritical CO2 -provide valuable reaction media that can facilitate the separation of reaction products and the recovery of catalysts. Chemistry in fluorous media requires that some of the protagonist molecules, and in particular the catalysts, be grafted with one or more perfluoroalkylated chains. These chains, due to powerful hydrophobic and lipophobic effects, tend to self-assemble and induce the formation of a variety of nanocompartmented supramolecular architectures and colloids, such as micelles, vesicles, tubules, monolayers, and emulsions, thus generating microheterogenicity in the reaction medium. Fluorinated amphiphiles are, for example, known to generate fibrous gels in fluorous, organic, and aqueous media. Phase separation, nanocompartmentation, and interface-driven parameters can thus complicate otherwise simple chemistry. Conversely, they can provide useful micro- and nanoreactors and templates. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4251,4258, 2006 [source] Single sample extraction protocol for the quantification of NAD and NADH redox states in Saccharomyces cerevisiaeJOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2008Jennifer L. Sporty Abstract A robust redox extraction protocol for quantitative and reproducible metabolite isolation and recovery has been developed for simultaneous measurement of nicotinamide adenine dinucleotide (NAD) and its reduced form, NADH, from Saccharomyces cerevisiae. Following culture in liquid media, yeast cells were harvested by centrifugation and then lysed under nonoxidizing conditions by bead blasting in ice-cold, nitrogen-saturated 50 mM ammonium acetate. To enable protein denaturation, ice cold nitrogen-saturated CH3CN/50 mM ammonium acetate (3:1 v/v) was added to the cell lysates. Chloroform extractions were performed on supernatants to remove organic solvent. Samples were lyophilized and resuspended in 50 mM ammonium acetate. NAD and NADH were separated by HPLC and quantified using UV,Vis absorbance detection. NAD and NADH levels were evaluated in yeast grown under normal (2% glucose) and calorie restricted (0.5% glucose) conditions. Results demonstrate that it is possible to perform a single preparation to reliably and robustly quantitate both NAD and NADH contents in the same sample. Robustness of the protocol suggests it will be (i) applicable to quantification of these metabolites in other cell cultures; and (ii) amenable to isotope labeling strategies to determine the relative contribution of specific metabolic pathways to total NAD and NADH levels in cell cultures. [source] Quenching with fluid jetsMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 5-6 2009S. Schuettenberg Verzugskompensation; Distortion Engineering; Jetabschreckung; Flüssigkeitsabschreckung Abstract The quenching process within the heat treatment of workpieces can be optimized by applying locally adapted quenching conditions. Locally variable heat transfer conditions at the workpiece surface are realizable by impressing and regulation of adjustable flexible flow fields on the basis of arrays for jet flow impingings on surfaces inside the quenching media. With use of these adapted jet fields it is possible to generate spatially and or timewise varying quenching conditions with high cooling intensities for a systematic locally heat transfer during the quenching process. For the analysis of workpiece distortion activated by heat treatment, the heat transfer and hardening process by quenching in adapted flexible flow fields is modelwise described. By controlled quenching with liquid media, the quenching intensities can be increased for specific local hardening results on massive workpieces. By that, the heat treatment process and the quenching result can be affected and optimized by controlling the boiling process and the establishing of the rewetting front on the workpiece surface. Abschrecken mit Flüssigkeitsjets Der Abschreckprozess bei der Wärmebehandlung von Werkstücken kann durch die Aufprägung lokaler Abschreckbedingungen optimiert werden. Lokal variable Wärmeübergangsbedingungen an der Werkstückoberfläche sind hier innerhalb des Abschreckmediums durch die Aufprägung und Regelung flexibler Strömungsfelder auf der Grundlage von Jetfeldern mit Prallströmungen auf die Oberflächen möglich. Mit der Anwendung dieser angepassten Jetfelder ist es möglich, räumlich und zeitlich variable Abschreckbedingungen mit hohen Kühlintensitäten für einen gezielten, lokalen Wärmeübergang während des Abschreckprozesses zu generieren. Zur Analyse des durch die Wärmebehandlung aktivierten Bauteilverzugs wird der Härteprozess durch Abschreckung in angepassten, flexiblen Strömungsfeldern modellmäßig beschrieben. Durch gesteuertes Abschrecken mit flüssigen Medien können die Abschreckintensitäten für bestimmte lokale Härteergebnisse an massiven Werkstücken erhöht werden. Damit kann das Abschreckergebnis durch die Steuerung des Siedeprozesses und des Verlaufs der Wiederbenetzungsfront an der Werkstückoberfläche beeinflusst und optimiert werden. [source] Isolation and characterization of bacteriophages specific for Campylobacter jejuniMICROBIOLOGY AND IMMUNOLOGY, Issue 10 2009Sunyoung Hwang ABSTRACT Human infection by Campylobacter jejuni is mainly through the consumption of contaminated poultry products, which results in gastroenteritis and, rarely, bacteremia and polyneuropathies. In this study, six C. jejuni -specific bacteriophages (CPS1,6) were isolated by the spot-on-the-lawn technique from chicken samples in Korea and characterized for potential use as biocontrol agents. All isolated bacteriophages exhibited a high specificity, being able to lyse only C. jejuni, but not other Gram,negative bacteria, including C. coli, Escherichia coli, Salmonella spp., and Gram,positive bacteria. Bacteriophages contain an icosahedral head and a contractile tail sheath in transmission electron microscopy, and possess ds-DNA with an average genome size of approximately 145 kb; therefore, all bacteriophages are categorized into the Myoviridae family. Bacterial lysis studies in liquid media revealed that CPS2 could be used to control the growth of C. jejuni. [source] SigB, an RNA polymerase sigma factor required for osmoprotection and proper differentiation of Streptomyces coelicolorMOLECULAR MICROBIOLOGY, Issue 1 2001You-Hee Cho A gene (sigB) encoding an alternative sigma factor ,B in Streptomyces coelicolor A3(2) was isolated and characterized. It encodes a polypeptide of 281 amino acids (31 546 Da) and is highly homologous to Bacillus subtilis,B. The sigB coding region is preceded by four open reading frames (ORFs): dpsA, orfA, rsbB and rsbA in sequential order. RNA analyses revealed that rsbB, rsbA and sigB constitute an operon (sigB operon). Transcripts were produced constitutively from a promoter (sigBp2) upstream of the rsbB coding region, contributing to the basal level expression of ,B protein. An inducible promoter (sigBp1) resembling the catB promoter (catBp) was located between the rsbA and sigB coding regions. Transcripts from sigBp1 dramatically increased as cells differentiated on solid media, at the stationary phase in liquid media or by osmotic stresses similar to the behaviour of catBp transcripts. Both catBp and sigBp1 promoters were recognized specifically by ,B -containing RNA polymerase in vitro. Disruption of the sigB gene abolished not only the differentiation-associated expression but also the osmotic induction of the catB gene, indicating that catBp is under the control of ,B. The sigB mutant exhibited a similar phenotype to the catB mutant, being sensitive to hyperosmolarity, blocked in forming aerial mycelium and with skewed antibiotic production. Therefore, we conclude that ,B ensures the proper differentiation and osmoprotection of S. coelicolor cells, primarily via regulation of the expression of catalase B. [source] Recovery of Homogeneous Polyoxometallate Catalysts from Aqueous and Organic Media by a Mesoporous Ceramic Membrane without Loss of Catalytic ActivityCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2006Sankhanilay Roy Chowdhury Dr. Abstract The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous ,-alumina membranes is reported. The recovery of Q12[WZn3(ZnW9O34)2] (Q=[MeN(n -C8H17)3]+) from toluene-based media was quantitative within experimental error, while up to 97,% of Na12[WZn3(ZnW9O34)2] could be recovered from water. The toluene-soluble POM catalyst was used repeatedly in the conversion of cyclooctene to cyclooctene oxide and separated from the product mixture after each reaction. The catalytic activity increased steadily with the number of times that the catalyst had been recycled, which was attributed to partial removal of the excess QCl that is known to have a negative influence on the catalytic activity. Differences in the permeability of the membrane for different liquid media can be attributed to viscosity differences and/or capillary condensation effects. The influence of membrane pore radius on permeability and recovery is discussed. [source] | ||||||||||||||||