Escherichia coli O157:H7 is a major food-borne infectious pathogen that causes diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. Here we report the complete chromosome sequence of an O157:H7 strain isolated from the Sakai outbreak, and the results of genomic comparison with a benign laboratory strain, K-12 MG1655. The chromosome is 5.5 Mb in size, 859 Kb larger than that of K-12. We identified a 4.1-Mb sequence highly conserved between the two strains, which may represent the fundamental backbone of the E. coli chromosome. The remaining 1.4-Mb sequence comprises of O157:H7-specific sequences, most of which are horizontally transferred foreign DNAs. The predominant roles of bacteriophages in the emergence of O157:H7 is evident by the presence of 24 prophages and prophage-like elements that occupy more than half of the O157:H7-specific sequences. The O157:H7 chromosome encodes 1632 proteins and 20 tRNAs that are not present in K-12. Among these, at least 131 proteins are assumed to have virulence-related functions. Genome-wide codon usage analysis suggested that the O157:H7-specific tRNAs are involved in the efficient expression of the strain-specific genes. A complete set of the genes specific to O157:H7 presented here sheds new insight into the pathogenicity and the physiology of O157:H7, and will open a way to fully understand the molecular mechanisms underlying the O157:H7 infection.

The photocatalytic decomposition of phenol in oxygenated aqueous suspensions of lightly-reduced anatase TiO2, being the most satisfactory among the semiconductors investigated from the standpoint of the photocatalytic activity and stability, has been investigated at the optimum pH 3.5. The products at the initial stage of the reaction were hydroquinone, pyrocatechol, 1,2,4-benzenetriol, pyrogallol, and 2-hydroxy-1,4-benzoquinone. These intermediates underwent further photocatalytic oxidation via acids and/or aldehydes finally into CO2 and H2O. A reaction scheme involving hydroxyl radicals as real reactive species has been proposed. Although H2O2 was formed via O2\ewdot produced by electron trapping of adsorbed oxygen, its concentration remained constant at a low value during the reaction. About 0.7 mole of O2 was consumed for the consumption of one mole of phenol at the initial stage of the reaction. These results indicated that hydroxyl radicals were formed not only via holes but also via H2O2 from O2\ewdot. It was interesting from the viewpoint of wastewater treatment that phenol was completely mineralized to CO2 in the presence of TiO2 powder under solar irradiation without both aeration and mixing of the solution.

A wool-like copper electrode used to produce non-thermal plasma functioned as an efficient catalyst for ammonia production from N and H under atmospheric pressure without heating. The catalytic activity increased as the experiments were repeated. The yield of ammonia at H/N = 3 was 3.5%. The intensity of the emission spectra of N*(C-B) bands was correlated with the ammonia synthesis rate.

Titanium nitride chloride (TiNCl), a band semiconductor with the α-form layered structure, becomes a superconductor with a transition temperature T c ≈ 18.0 K by electron doping via alkali-metal intercalation. Upon cointercalation of various kinds of organic solvent molecules with alkali atoms, the superconducting layered crystals are swelled to different extents adjusting to the size of the molecules, and the T c decreases linearly down to 6.5 K as a function of 1/d, where d is the interlayer separation (basal spacing) of the expanded nitride layers, implying the importance of the Coulomb interlayer coupling for superconductivity. This is in strong contrast to a previous finding that the T c of the electron-doped ZrNCl and HfNCl with the β-form layered structure rather increases with the increase of d upon a similar cointercalation of solvent molecules.

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