ABSTRACT
Temperature dependences of NMR spectra have been observed for 23Na and 27Al in the metallic phase of Na-K form low silica X (LSX) zeolite loaded with potassium, where the condition of saturation is achieved with a loading level of 9.0 atoms per supercage and the paramagnetic moment contributes to the magnetism of the system beyond simple isolated spin. Two separated peaks have been recognized for 23Na, where the shift values show a quite linear relationship with susceptibility, and the so-called K-χ plot works quite well to give values of 0.32 kOe µB-1 and 0.40 kOe µB-1 for hyperfine coupling constants. Although no separated peak is seen in the 27Al NMR spectrum, the spectral centroid deviates to the positive side. The shoulder of the spectrum scales to susceptibility and the K-χ plot also works well to give a value of 0.15 kOe µB-1 for the hyperfine coupling constant. The orbital of potassium-originated electrons confined in the cage of LSX is understood as seeping out over the framework of zeolite, which is wider than that of the sodium-originated case.
ABSTRACT
Staphylococcus aureus is a gram-positive pathogen that causes a variety of diseases, including bovine mastitis, which has severe economic consequences. Standard antibiotic treatment results in selection of resistant strains, leading to a need for alternative treatments, such as bacteriophage therapy. Forty-nine S. aureus isolates were obtained from the milk of mastitic cows for use in screening of staphylococcal phages. Fifteen isolates which were positive for both coagulase and hemolysin were assayed by PCR for variation in the X region and the immunoglobulin G-binding region of the protein A gene (spa) and in the carboxy terminus of the coagulase gene (coa) and for the presence of enterotoxin C, G, H, and I genes. The host ranges of 52 phages isolated from sewage influent were determined by performing spot tests with the 15 S. aureus isolates, and two phages were subsequently chosen for further analysis. PhiSA039 had the widest host range, producing clear plaques on 13 of the 15 isolates (87%), while PhiSA012 produced clear plaques on 8 isolates (53%) and was the only phage that produced a clear plaque on a nonmastitic S. aureus strain. Transmission electron microscopy revealed that the phages were similar sizes and belonged to the Myoviridae family. Measurement of optical densities during coculture with S. aureus isolates confirmed the breadth of the PhiSA039 host range and showed that PhiSA012 had potent lytic capability. PhiSA012-resistant bacteria did not appear for three of seven isolates tested (43%) after 65 h of incubation. These two phages are proposed as candidates for phage therapy of bovine mastitis.
Subject(s)
Bacteriolysis , Sewage/virology , Staphylococcus Phages/growth & development , Staphylococcus Phages/ultrastructure , Staphylococcus aureus/genetics , Staphylococcus aureus/virology , Animals , Bacterial Proteins/genetics , Cattle , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Mastitis, Bovine/microbiology , Microscopy, Electron, Transmission , Molecular Sequence Data , Myoviridae/ultrastructure , Sequence Analysis, DNA , Staphylococcus Phages/classification , Staphylococcus Phages/isolation & purification , Staphylococcus aureus/isolation & purification , Virion/ultrastructureABSTRACT
Photoinduced electron transfer reaction of 2-bromomethyl-2-(3-butenyl)benzocyclic-1-alkanones with amines afforded 5-exo radical cyclization products while electron transfer reaction with samarium diiodide produced cyclopropanols.
ABSTRACT
The application of bacteriophages (phages) in therapy urgently requires the production of wide-host-range recombinant phages that possess strong lytic activity. The wide-host-range IP008 phage was classified by transmission electron microscopy analysis as an A2 morphotype member of the Myoviridae family of the order Caudovirales. IP008 showed a high homology (99.4% similarity in the amino acid alignment of the major capsid protein Gp 23) with KEP10, another wide-host-range phage. The long tail fiber genes (genes 37 and 38) from the genome of T2 were replaced with those of the IP008 phage by homologous recombination. The host range of the recombinant phages was identical to that of IP008. Furthermore, the recombinant phage bacterial lytic activity was restored. Future analyses of host-range mutants of the closely related phages T2 and IP008 could lead to a more precise localization of the genetic factors responsible for receptor specificity.