A bis-quaternary ammonium compound (bis-QAC), N, N'-hexamethylenebis (4-carbamoyl-1-decylpyridinium bromide) (D-38), which has 6 carbon atoms in the connecting methylene chain and 10 carbon atoms in the N-alkyl chain, was synthesized and characterized. D-38 exhibited a wide-ranging and effective antimicrobial action against both bacteria and fungi, compared with those of typical bactericides, such as benzyldodecyldimethylammonium chloride (BAC) and cetylpyridinium chloride (CPC), or popularly-used fungicides, such as 2-(4-thiazolyl) benzimidazole (TBZ) and 1, 2-benzisothiazol-3-one (BIT). D-38 showed a high bactericidal activity in the ranges of pH 5 to 8.5, and 10 to 40°C, in contrast to mono-QAC, N-dodecylpyridinium iodide (P-12), and the activity of D-38 was little influenced by pH and temperature. Furthermore, urethane sheets containing D-38 were prepared for practical use, and the antibacterial and antifungal efficiency was evaluated. Tests on the antibacterial efficiency of the D-38 sheets were carried out against two strains of bacteria (Staphylococcus aureus IFO 12732, Escherichia coli IFO 3972) according to the film covering method. Additionally, tests on the fungus resistance of the sample were performed by using the mixed spore suspension (Aspergillus niger IFO 6341, Penicillium citrinum IFO 6352, Rhizopus oryzae IFO 31005, Cladosporium cladosporioides IFO 6348, Chaetomium globosum IFO 6347). The growth of both bacteria and fungi was inhibited on sheets containing D-38.

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A thin film of titanium dioxide (TiO₂, anatase crystalline form) coated on a glass plate inactivated Lactobacillus casei PL-1 phages suspended in a buffer solution, when the reaction mixture was illuminated with a black-light lamp (maximum wave length, 365 nm) and shaken gently. When the reaction mixture was not illuminated, the TiO₂ film exhibited no phageinactivating activity. TiO₂ was not photoexcited by white (fluorescent)-light lamp. The degree of phage inactivation was directly proportional to the surface area of the TiO₂ film. The phage inactivation approximately followed first-order reaction kinetics. The phage inactivation by photoexcited TiO₂ film was inhibited by superoxide dismutase and D-mannitol, and accelerated by hydrogen peroxide, indicating that the phage inactivation is due to the active oxygen species generated on the surface of TiO₂ film under the black-light illumination. Electron microscopic observation of the negatively-stained preparation revealed that about 43% of the phages treated with photoexcited TiO₂ film were converted into ghost-particles with empty heads.

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We investigated the change in the location of intracellular proteins in Escherichia coli cells after heat treatment at 55°C in a buffer. After heat treatment, the amount of soluble proteins in cell extracts decreased and those of urea-soluble proteins, which were sedimented by highspeed centrifugation and then solubilized with 6 M urea solution, increased correspondingly. Based on the sucrose density gradient ultracentrifugation analysis, two separate peak fractions of the sedimentary intracellular proteins appeared. One was sedimented at the bottom and the other was cosedimented with the membranes. The sedimentary intracellular proteins in a rpoH mutant of E. coli after heat shock to 45°C in a growth medium were also separated in two peak fractions, as in its parent strain heated at 55°C in the buffer, whereas they were hardly detected in the case of the parent strain after the heat-shocked to 45°C. In the case of an IbpAB-overexpressing strain heated to 50°C in a growth medium, sedimentary intracellular proteins did not seem to be cosedimented with the membranes and also protein aggregation decreased, compared with the case of its parent strain heated at 50°C. These results suggest that heat-denatured intracellular proteins not only aggregate but also interact with the membranes and also that at least some of heat shock proteins including IbpAB may be involved in the suppression of protein aggregation.

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(R)-and (S)-13-Hydroxy-10-oxo-trans-11-octadecenoic acid (1) were synthesized from (R)- and (S)-2-[(S)-O-methoxyethoxymethylmandelyloxy] heptanal (2R and 2S) and 10-oxoundecanol tetrahydropyranyl ether (3).(R)-acid showed antimutagenic activity against the UV-induced mutation of Escherichia coli.

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Since Legionella species, the causative organisms of Legionnaires' disease, are known to multiply in amoebal cells and survive disinfection treatments, it is necessary for biocides in order to control Legionella species to also be lethal against the host-amoeba. 4, 4'-(1, 6-Hexamethylenedithio) bis (1-octylpyridimium iodide) (4DTBP-6, 8) and N, N'-1, 6-hexamethylenebis (1-decyl-4-carbamoylpyridinium bromide) (D-38) are the novel bis-quaternary ammonium compounds (bis-QACs), which show a wide and effective antimicrobial activity against both bacteria and fungi and exhibit low toxicity, compared with N-dodecylpyridinium iodide (P-12), a mono-QAC with a typical structure, and 2-bromo-2-nitropropane-1, 3-diol (Bronopol), which has been used as a major organic biocide against Legionella species in cooling towers. The biocidal effect of these bis-QACs was investigated against Legionella species, L. pneumophila AQ 998, L. pneumophila GIFU 9134 and L. bozemanii GIFU 9140, and Acanthamoeba 96. The bis-QACs showed higher bactericidal activity against Legionella species than the comparative biocides. Amoebicidal activity was estimated by the direct cellcounting method and ATP assay based on luciferase-catalyzed reaction to assess the biocidal ability against both trophozoites and cysts. The bis-QACs, 4DTBP-6, 8 and D-38, had amoebicidal activity at the concentration of 10mg/l, while the mono-QAC, P-12, had cysticidal activity above the concentration of 100mg/l, and Bronopol had no amoebicidal activity but had growth-inhibitory effect below the concentration of 100mg/l.

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In order to evaluate the adaptation response to antifungal agents with an action mechanism involving H₂O₂ generation, it is necessary to develop a test fungus properly adapted to H₂O₂. This study reports that the menadione (MD) treatment method is a useful one in the case of 2 yeast strains; Saccharomyces cerevisiae IFO 0565 and Candida albicans ATCC 10231. When these cells were treated with MD at 1mM for 1 h, the enzyme activity of catalase distinctively increased, while the superoxide dismutase activity did not. Thus cells adapted to H₂O₂ showed marked increase in their survival rate against the challenge of H₂O₂ stress.

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Ozone inactivation of lactic acid bacteria in water was studied. The strains studied showed resistance to ozonated water in the following order: Leuconostoc mesenteroides IFO3426>Lactobacillus fructivorans IFO 13118>Lactobacillus plantarum IFO3070>Weissella viridescence IFO3949>Enterococcus faecium IFO3128>Enteroccoccus feacalis IF012964. However, the survival ratio of L. mesenteroides IFO3426 was found to decrease by increasing the dissolved ozone concentration ranging from 0.5 to 5mg/l and the temperature in the range from 5 to 30°C.

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Eight strains of cytochrome P450 (P450)-producing bacteria were isolated from M9 medium containing a P450-inducer as the sole carbon source from the environment. Strains EP1 to EP6 utilizing 2-ethoxyphenol as the sole carbon source were isolated from the soil of a weed-filled field, the water of a paddy field, laboratory effluent, domestic effluent and river water. Strain MP1 utilizing 2-methoxyphenol and strain CP1 utilizing camphor were isolated from oil-polluted soil and the soil of a weed-filled field, respectively. This suggests the distribution of P450-producing bacteria in the environment. Metyrapone (2-methyl-1, 2-di-3-pyridyl-1-propanone) inhibited the growth of P450-producing bacteria on the media containing a P450-inducer as the sole carbon source, strongly suggesting that the P450 is involved in the catabolism of the inducer.

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Degradation of dichloromethane (DCM) by two environmental isolates, Flavimonas sp. strain P3310 and Chryseobacterium sp. strain G31, were studied. The ability of the strains was raised to degrade 3, 000 mg/l of DCM by acclimatization, although the original isolates could degrade less than 500 mg/l. The first step in the degradation process was dechlorination, and the liberated chloride ions caused the reduction of pH and the bacterial growth; the addition of phosphate salts, however, restored the growth and the degrading ability of the culture by increasing the buffer capacity. The DCM-degrading activity was also detected in the cell-free extract and the culture-supernatant. These results suggest that the isolates or their products are possible candidates for bioremediation to eliminate DCM pollution.

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We examined the killing effect of peracetic acid on two filamentous fungal strains, Arthrinium sacchari M001 and Chaetomium funicola M002. The resistance of A. sacchari M001 to peracetic acid was lower than that of Ch. funicola M002, and the latter strain was more appropriate as an indicator microorganism for container sterilization in the aseptic PET bottle filling method. The 6D value of Ch. funicola M002 at 500 μg/ml was as low as 6.22min even with 48°C, the highest temperature tested. At a concentration of 2, 500μg/ml, the 6D value was 3.36 min at 39°C but decreased to 0.67min at 48°C.

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It has been reported that high hydrostatic pressure (HHP) treatment at 400 MPa or higher inactivated a laboratory strain of human immunodeficiency virus type 1 (HIV-1). We investigated the effects of HHP treatment on the infectivity and reverse transcriptase (RT) activity of HIV-1. The sensitivity to HHP treatment differed among the HIV-1 strains. The pressure required for the inactivation of two clinical isolates was over 100 MPa higher than that of the laboratory strain. The RT activity of HIV-1 treated by HHP closely correlated with the decrease in the infectivity of each of the three strains tested. The decrease in the activity of RT may be related to the reducing the infectivity of HIV.

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