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Pseudomonads, including P. fluorescens strain MKB 158, can inhibit the development of Fusarium seedling blight disease on wheat and barley. Application of this and other pseudomonads as head sprays inhibits the development of Fusarium head blight disease (FHB) disease on wheat and barley under both field and glasshouse conditions. P. fluorescens strains MKB 158 and MKB 249 also reduced DON contamination of grain under field conditions. Evidence suggests that P. fluorescens does not directly inhibit the growth of Fusarium , but that it potentiates host resistance against this disease. Transcriptome profiling identified barley genes differentially expressed as early events in (a) bacterium-induced resistance to seedling blight and (b) heads following P. fluorescens and Fusarium culmorum co-inoculation. Bacterium-potentiated resistance to Fusarium affects the transcription of many genes that are involved in diverse processes, including cell rescue and defence, metabolism, cell cycle and DNA replication and signalling.

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24 1513 1519 Simon-Colin, C., Raguenes, G., Cozien, J., Guezennec, J. G.: Halomonas profundus sp. nov., a new PHA-producing bacterium isolated

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A multienzyme complex from newly isolated Paenibacillus sp. TW1 was purified from pellet-bound enzyme preparations by elution with 0.25% sucrose and 1.0% triethylamine (TEA), ultrafiltration and Sephacryl S-400 gel filtration chromatography. The purified multienzyme complex showed a single protein band on non-denaturing polyacrylamide gel electrophoresis (native-PAGE). The high molecular mass of the purified multienzyme complex was approximately 1,950 kDa. The complex consisted of xylanase and cellulase activities as the major and minor enzyme subunits, respectively. The complex appeared as at least 18 protein bands on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and as 15 xylanases and 6 cellulases on zymograms. The purified multienzyme complex contained xylanase, α-L-arabinofuranosidase, carboxymethyl cellulase (CMCase), avicelase and cellobiohydrolase. The complex could effectively hydrolyze corn hulls, corncobs and sugarcane bagasse. These results indicate that the multienzyme complex that is produced by this bacterium is a large, novel xylanolytic-cellulolytic enzyme complex.

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Abstract  

The utilization of carrier-free ionic18F is a convenient method for studying the effects of very low extracellular fluoride concentrations on the metabolism of the cariogenic bacterium Streptococcus mutans. We have developed a method for the preparation of carrier-free aqueous solutions of ionic18F with high specific activity (about 707 Bq/ml). Fluoride distribution and fluoride binding experiments showed that submicromolar fluoride concentrations have already a negative effect on the metabolism of Streptococcus mutans.

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Direct bioautography is a potent means of obtaining information about the antimicrobial activity of a compound separated from a complex mixture. In this process the developed TLC plate is dipped into a broth culture of a test bacterium and the bacterium will grow directly on the plate. Optimum experimental conditions must, however, be used for each test bacterium.The main purpose of this study was to find optimum culture conditions for a Gram-negative test bacterium, Escherichia coli (ATCC 25922) enabling us to establish a direct bioautographic method with the shortest possible performance time. Because the intracellular adenosine-5′-triphosphate (ATP) level is a direct and sensitive measure of bacterial well-being, ATP assay was used for this purpose. As far as we know this is the first report of the use of an ATP method for optimization of direct bioautography with E. coli . Our optimizing experiments on E. coli culture showed that the bacteria had to be in the log phase (optical density, OD 600nm = 0.1–0.4) in the bacterial suspension used for dipping. TLC plates immersed in the log-phase culture needed a shorter incubation time for bacterial growth on the TLC plate (3 h) than for the original ‘overnight’ culturing suggested in studies by others.In this paper we will show that:

  1. ATP assay is a valid method for optimizing E. coli direct bioautography. Bacterial ATP level oscillates during the growth phase in culture media. TLC plates should be immersed in E. coli dipping suspension with OD 600nm = 0.1–0.4. Dipping a developed TLC plate for 10 s gave acceptable results. Incubation of the seeded TLC plate at 37°C for 3 h was found to be optimum. An ATP/protein ratio of 10–15 nmol mg −1 in dipping culture and ∼5 nmol mg −1 on seeded TLC plates were the minimum threshold values for visualization of living bacteria by means of the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) reaction. With our optimized coditions the total performance time of E. coli direct bioautography is 9.6 h instead of the originally reported 11.5 h. Our procedure results in much sharper contrast of the inhibition zone than that without optimization.

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bacterium Alicyclobacillus acidocaldarius: Identification of the active site residues . Biochim. Biophys. Acta , 1784 , 292 – 301 . L OWRY , O.H. , R OSEBROUGH , N.J. , F ARR , A

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Authors: László Zsiros, Ágnes Szatmári, László Palkovics, Zoltán Klement and Zoltán Bozsó
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Authors: Hagen Frickmann, Andreas Hahn, Stefan Berlec, Johannes Ulrich, Moritz Jansson, Norbert Georg Schwarz, Philipp Warnke and Andreas Podbielski

Introduction: Escherichia coli and Staphylococcus aureus are important causes of severe diseases like blood stream infections. This study comparatively assessed potential differences in their impact on disease severity in local and systemic infections.

Methods: Over a 5-year interval, patients in whom either E. coli or S. aureus was detected in superficial or primary sterile compartments were assessed for the primary endpoint death during hospital stay and the secondary endpoints duration of hospital stay and infectious disease as the main diagnosis.

Results: Significance was achieved for the impacts as follows: Superficial infection with S. aureus was associated with an odds ratio of 0.27 regarding the risk of death and of 1.42 regarding infectious disease as main diagnosis. Superficial infection with E. coli was associated with a reduced duration of hospital stay by −2.46 days and a reduced odds ratio of infectious diseases as main diagnosis of 0.04. The hospital stay of patients with E. coli was increased due to third-generation cephalosporin and ciprofloxacin resistance, and in the case of patients with S. aureus due to tetracycline and fusidic acid resistance.

Conclusions: Reduced disease severity of superficial infections due to both E. coli and S. aureus and resistance-driven prolonged stays in hospital were confirmed, while other outcome parameters were comparable.

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