Novel tris-quaternary ammonium compounds (tris-QACs), 4, 4', 4''-(1, 2, 3-propylenetrithio)- tris (1-alkylpyridinium iodide)s (4TP-n: alkyl chain length, n= 4, 6, 8, 10, 12 or 14) were synthesized and characterized. The chemical structure of 4TP-n is a tris-structure that is composed of three N-alkyl-4-thiopyridinium iodides attached to propane positions 1, 2 and 3. Its antimicrobial characteristics were compared to those of 4, 4';-(1, 6-hexamethylenedithio) bis (1-alkylpyridinium iodide) (4DTBP-6, n), a bis-quaternary ammonium compound (bis-QAC), and N-alkylpyridinium iodide (P-n), a mono-quaternary ammonium compound (mono-QAC), for both of which there are previous reports on their syntheses and antimicrobial characteristics. Moreover, 4TP-n was also compared to benzyldimethyldodecylammonium chloride (BAC) and 2-(4-thiazolyl) benzimidazole (TBZ) as antibacterial and antifungal agents that are widely used in various industries. Both the bacteriostaticactivity and the bactericidal activity of 4TP-n were higher than those of P-n and were similar to those of 4DTBP-6, n, and were scarcely affected by the length of the alkyl chain unlike the typical mono-QAC, P-n. 4TP-8 exhibited a more wide-ranging and more effective antimicrobial activity against bothbacteria and fungi in comparison with P-12, BAC and TBZ although the antifungal activity of 4TP-8was lower than that of 4DTBP-6, 8. While the bactericidal activity was influencedby pH and temperature, 4TP-n showed a higher bactericidal activity in the ranges of pH 5 to 8.5 and 10 to 40°C than P-12.

View full abstract

When the log-phase cells of Bacillus subtilis 168 were exposed to a cold shock drop in temperature from 37 to 0°C followed by incubation at 37°C or a heat shock rise in temperature from 37 to 55°C, their chromosomal DNA was found to be cleaved, when detected by agarose electrophoresis. The DNA fragmentation in vivo was observed in Spizizen minimal medium containing Ca²⁺ or Mn²⁺ but not in Mg²⁺. DNA fragmentation was inhibited by the addition of an endonuclease inhibitor, aurintricalboxylic acid (ATA), but not by Zn²⁺. By using the DNase ymographic analysis of the cell-free extract, Ca²⁺ or Mn²⁺-dependent DNase bands having molecular masses of 60, 39, 28 and 17 kDa were detected. Among those, the 17 kDa DNase was confirmed to be produced from the nucA gene by the nucA deletion mutant analysis.The extent of DNA cleavage and total DNase activity in the nucA mutant were similar to those of the parent strain, indicating no involvement of this enzyme in the DNA fragmentation caused by thermal shock treatments. On the other hand, since the 39 kDa DNase was found to be a Zn 2⁺-resistant type different from other DNases detected, this DNase is suggested to be a major factor involvedin the DNA fragmentation observed here.

View full abstract

Hydrotalcites containing copper (Cu-HT) were synthesized using MgCl₂, AlCl₃and CuCl₂, and hydrotalcites containing zinc (Zn-HT) were synthesized using MgCl₂, AlCl₃ and ZnCl₂ Their disinfection activities against Escherichia coli, Staphylococcus aureusandE. coli phage Q β (phage Qβ) were investigated by the shake-flask method. Cu-HT possessed strong disinfection activities against E. coil and phage Qβ, whereas Zn-HT showed bactericidal activity against E. coil, S. aureus and phage Qβ. Copper elution from Cu-HT was undetectable during the disinfection test. The disinfection activity of Cu-HT was due to the presence of copper. The pH of Cu-HT suspensions was pH 9.3 as a result of the hydration reaction at the surfaces of the Cu-HT particles. The remarkable disinfection activity of Cu-HT against phage Qβ seemed to be based on the cooperative action of copper in Cu-HT and the direct contact of phage Qβ cells to the hydroxyl layers on the surfaces of the Cu-HT particles. We propose that Cu-HT can be used as an alternative disinfectant to chlorine in a water purification system.

View full abstract

The effects of laundering and light-exposure on the antimicrobial activities of cotton fabrics (4 samples) finished with metal salts such as copper or zinc against Staphylococcus aureus IFO 3060, Klebsiella pneumoniae IFO 13277 and Trichophyton mentagrophytes IFO 5466 were investigated and compared with those on the activities of commercially available antibacterialdeodorant fabrics. Antimicrobial activities of the test fabrics against these test strains were stronger than those of the commercial fabrics tested, except for test sample no.3, a plain cottonfabric with a Zn²⁺ absorption dose of 1.07mg/g fabric, against K. pneumoniae. Even after 30 laundry cycles and 10 days of light-exposure, the antimicrobial activities of the test fabrics finished with metal salts were still stronger than the similarly tested commercial ones, except for sample no. 3 against K. pneumoniae. These results suggest that the test fabrics finished with metal salts (with the exception of sample no.3) could be valuable to the development the field of antimicrobial fabrics, be used for various practical items such as bathroom mats, towels and socks, and could contribute considerably to the greater hygiene of all textiles general.

View full abstract

Cotton cloths combined with chemicals of plant origin were prepared and their antimicrobial activities were investigated. Tannic acid and berberine, respectively, were fixed onto aminoethylated and carboxymethylated cotton cloths. Escherichia coli W3110 and Staphylococcus aureus IFO 13276 were used as the representatives of bacteria. Both aminoethylated- and carboxymethylated clothes, by themselves, showed a considerable antibacterial activity. Fixation of tannic acid and berberine onto the cloths enhanced the antibacterial activity. The cloths showed higher antibacterial activities against E. coli than against S. aureus. SEM observation after the test revealed that E. coil cells were totally collapsed on the surface of the cloth, while some S. aureus cells were observed to remain in the normal shape. The cloth fixed with tannic acid withstood 20 times of washing by acloths-washer with laundry soap.

View full abstract

The antibacterial activity of the agent of a wet disinfectant mat (WDM) utilizing benzalkonium chloride (BAC) and sodium carbonate was researched. The agent of the WDM showed a bactericidal activity in which there was a decrease of 10⁷cfu/ml or more in all the strains tested in an exposure of 30 s or more. On the WDM, Staphylococcus aureus showed blebs after 30 min, and remarkable destruction of bacteria body was also observed. After 2.5h on the WDM, the whole bacterial body of Salmonella enteritidis was covered with many irregular blebs. In the early stage at 5 min after pouring the bacterial suspension on the WDM, embedding of S.enteritidis in the drug layer was observed. These results suggested thatthe WDM would trap and kill microorganisms in food factories.

View full abstract

Six strains of fungi that degrade formaldehyde were isolated from the soil. Strain no. 5 degraded formaldehyde concentrations as high as 2.0% within 20 days. Colonial and morphological properties indicated that strain no.5 belongs to the genus Paecilomyces. This strain proliferated in medium containing 1.5% formaldehyde as the sole carbon source. The upper concentration limit of formaldehyde that permitted fungal growth was 2.4% and strain no. 5 degraded that concentration offormaldehyde completely within 55 days.

View full abstract

Since 1-(2-oxocyclopentyliden)-2-alkanols (1) showed enhanced bio-antimutagenic activity against UV-induced mutagenic Escherichia coli WP2 B/r trp, 1-(2-oxocyclopentyliden)-3-oxaand 3-thiaalkanes (4 and 7) and 10-(2-oxocyclopentyliden)-8-oxadecanol (5) were synthesized, and their bio-antimutagenic and bactericidalactivity were measured. 10-(2-Oxocyclopentyliden)-8-oxadecanol (5) showed weakactivity (AD₅₀, 95.5 μg/ml), while 1-(2-oxocyclopentyliden)-3-oxanonane (4a) and 1-(2-oxocyclopentylidene)-3-thianonane (7) showed bactericidal activity (ID₅₀, 7.5 and 11.0 μg/ml, respectively).

View full abstract

In order to investigate the contribution of the multidrug efflux pumps to cellular resistance to a variety of agents including cationic surfactants, we cloned genes of major drug efflux pumps of Escherichia coli and transformed strain JM109with plasmids encoding those genes.In emrAB-, mdfA- and emrE-recombinants, the resistance to carbonylcyanide-m-chlorophenylhydrazone (CCCP), chloramphenicol, and paraquat, respectively, was increased compared to their parent bearing pUC18. Also, in mdfA- and emrE-recombinants, the resistance to cetyltrimethylammonium bromide (CTAB) was increased. However, no significant effects of abundant numbersof emrD and envCD could be observed on resistance to agents examined.

View full abstract

In order to improve the hydration resistance and handling of calcium oxide (CaO) as an antibacterial agent, CaO pellets containing ferric oxide (Fe₂O₃) (COPFe) were prepared by heating the mixture of calcium carbonate and Fe₂O₃. The pellets could keep their shapein water for a long time, and thus the hydration resistance was markedly increased. The COPFe treatment decreasedthe viable counts of bacteria in shredded cabbage, and coliforms were not detected after 5 min with as little as a 0.1% COPFe treatment. During the storage of the cabbage at 4°C for48h, an increase in aerobe counts on shredded cabbage was observed for water treatments but not for COPFe treatment and other treatments (NaOH and sodium hypochlorite).

View full abstract

The cytotoxicity of extracts from Alternaria alternata against tobacco Bright Yellow-2 (BY-2) cells was investigated by a simultaneous double-staining procedureusing fluorescein diacetate and propidium iodide. The active fraction from a 10-day-old culture filtrate of the fungus was purified by ammonium sulfate precipitation, ultrafiltration, gel filtration on Sephadex G-10, and reversed-phase HPLC, in sequence. The partially purified principle appears to be heat- and acid-stable, as neither incubation at 100°C for 30 min nor overnight treatment at pH2 altered the cytotoxicity. The cytotoxicity of the principle was abolished after treatment with proteinase K or trypsin, while the dithiothreitol treatment showed reduced cytotoxicity.

View full abstract