Hydroxyl radical (OH ·) was produced under visible light as an oxidized product and superoxide anion (O2 ·) as a reduced product from silver-loaded hydrogen zirconium phosphate [Ag1-xHxZr2 (PO4) 3] suspension in air. These radicals showed the electron spin resonance (ESR) spectra of 5, 5-dimethyl-1- pyrroline-N-oxide (DMPO) adducts, and usually only DMPO-OH can be obtained because of the rates of reaction between DMPO and OH · and O2 · The ESR spectrum of DMPO-O2- emanated in the presence of I- because I- is a trapping reagent of OH ·.I- acted first as an inhibitor and finally as did the bactericidal species in the bactericidal activity against Escherichia coli. I2 formed from the reaction between OH · and I-.This indicated that OH · was a bactericidal species. OH · produces (CH3) 2 C · OH and CH3C · H OH from ethyl alcohol and isopropyl alcohol because the redox potential of OH · is much more positive than those of the alcohols. Those radicals showed stronger bactericidal activities than OH ·. We propose that the strong reducing species has higher bactericidal activity against E. coil than the strong oxidizing species.
A new bis-quaternary ammonium compound (bis-QAC), 4, 4'-(tetramethylenedicarbonyldiamino) bis (1-decylpyridinium bromide) (D-136) was synthesized, and its antimicrobial and deodorant characteristics were studied. A vinyl chloride polymer sheet containing D-136 (D-136 sheet) was prepared for practical use because D-136 exhibited a wide and effective antimicrobial spectrum of activity against both bacteria and fungi. The antibacterial and antifungal efficiency of the D-136 sheet was estimated according to the film covering method and the test for fungus resistance. Results showed that the growth of both bacteria and fungi was inhibited on the D-136 sheet. Furthermore, a model test for the deodorant efficiency of water-absorbing resins (SAP) containing D-136 (D-136 SAP) was done on the assumption that it might be applied for use in disposable diapers. To prevent the offensive odor arising from excreted urine in disposable diapers, it is necessary to inhibit the propagation of ureahydrolyzing bacteria in the water-absorbing layer. The microbe used for the experiment was Proteus mirabilis IFO 3849 which produces an enzyme (urease) capable of degrading urea and other compounds present in human urine to ammonia, methylamine and the like. As for the result of the model test, the generation of ammonia from human urine was inhibited on D-136 SAP.
Differentiating viable cells from nonviable cells is of considerable importance in the monitoring of food-borne pathogens. A reverse transcription-polymerase chain reaction (RT-PCR) assay was developed to detect mRNA from the phospholipase gene (phl) of Vibrio mimicus. Viable V. mimicus cells were killed by heat or ethanol treatment and kept for various periods at room temperature. Total RNA from V. mimicus was extracted, treated with DNase and subjected to RT-PCR with primers for the phl gene. The phl mRNA was detected in the viable cells, but it gradually disappeared when the killed cells were left at room temperature and became undetectable after 8 h of storage. Furthermore, RT-PCR generated a 493 by fragment from the total RNA extracted from as few as about 103 organisms, confirming the sensitivity of the assay. The amplification of the phl mRNA was specific for V. mimicus, as no amplification was found when fifteen other Vibrio species and seven related organisms were tested. The results indicated a good relationship between the detection of the phl mRNA and viability of V. mimicus cells because the phl transcript is rapidly degraded upon cell death. This work shows the usefulness of RT-PCR as a sensitive method for the specific detection of viable V. mimicus.
The effect of ozone on the surface charge and cleanability of stainless steel was studied, using nonporous stainless steel particles. Stainless steel particles were treated with gaseous ozone generated from a pure oxygen-fed ozonizer at concentrations of 0.05 to 1.0% (v/v). Xray photoelectron spectroscopic analysis showed no significant differences in the binding energies of elements and composition of the outermost surfaces of stainless steel after ozone treatment. Adsorption isotherms of water vapor showed slightly lower affinities for ozonetreated stainless steel particles than for non-ozone-treated particles. In addition, the apparent points of zero charge (pzcapp) of ozone-treated stainless steel particles were situated at points corresponding to more acidic pH values compared with the pzcapp of non-ozone-treated particles. The effects of ozone on the surface properties of stainless steel particles depended on the ozone concentration. These results indicated that the degree of hydroxylation of stainless steel surfaces was reduced by ozone treatment. As a result of ozone treatment, the amount of bovine serum albumin (BSA) adsorbed on stainless steel particles decreased, and the rate of BSA desorption during alkali cleaning increased, probably due to the lower surface charge densities of ozone-treated stainless steel particles.
Surface treatment of stainless steel by ozonized air was investigated over the range of 0.01 to 0.2% (v/v) ozone (O3), using nonporous stainless steel particles. Ozonized air contained nitrogen oxides (NOx) at a NOx/O3 ratio of approximately 0.04. When stainless steel particles were treated with ozonized air, nitric acid was formed on their surfaces depending on the O3 concentration. As a result of ozonized air treatment, the adsorption affinity of water vapor for stainless steel particles decreased and the absolute values of the apparent surface charge density (σapp) of stainless steel particles decreased over the pH range of 3 to 10, resulting in the lower adsorption affinity of bovine serum albumin (BSA). The σapp curves of stainless steel particles treated with ozonized air at 0.15 to 0.2% O3 were very similar to the curves of the particles treated with 10 and 30% HNO3. These results indicated that nitric acid formed during ozonized air treatment brought about the modification of the surface charge of stainless steel particles. Ozonized air pretreatment of stainless steel particles fouled with BSA or calcium hydrogenphosphate markedly facilitated their removal during subsequent alkali cleaning or rinsing through O3 oxidation or descaling with nitric acid.
Alumina (Al2O3) particles fouled with bovine serum albumin (BSA) were cleaned with alkaline electrolyzed water and NaOH solutions of different pHs. The efficiency and rate of BSA desorption during batchwise and continuous cleaning with alkaline electrolyzed water depended on the solution pH, i.e., the hydroxide ion concentration. Pretreatment of BSA-fouled Al2O3 with 0.3% (v/v) gaseous ozone markedly facilitated BSA desorption during subsequent cleaning with alkaline electrolyzed water, depending on the length of pretreatment. The results suggest that the efficiency of cleaning with gaseous ozone and alkaline electrolyzed water (pH 11.7) in combination is comparable to that of cleaning with high-pH NaOH solutions (pH>13.0) alone.
Alcohols showed bactericidal activity against Staphylococcus aureus, Micrococcus luteus, Escherichia coli, and Enterobacter cloacae suspended in 0.85% (v/v) saline in the order of n-butanol>n-propanol>ethanol>methanol.Against the bacteria suspended in n-octane, however, alcohols showed a reverse order of bactericidal effectiveness. When toluene as a hydrophobic solvent was mixed with a small amount of hydrophilic methanol (5 or 10%, v/v), or conversely, when hydrophilic methanol was mixed with a small amount of hydrophobic nhexane (10 or 30%, v/v), the bactericidal activity of the mixture increased markedly. The pattern of the relative glucose-Sudan III solubility curve was similar to that of the bactericidal activity curve of ethanol solutions. The results obtained suggest that the bactericidal activity of an alcohol was not dependent on the logarithm of the partition coefficient of the alcohol but on the hydrophobicity-hydrophilicity balance of the solution.
Since the oil-based extract of licorice (Glycyrrhiza glabra L.) (OEL) has been found to have high fungicidal effect against Arthrinium sacchari M001 and Chaetomium funicola M002, we studied the structure of an antifungal substance derived from OEL which showed effectiveness against the above two filamentous fungi. Consequently, glabridin (glabridin, 3-(2', 4'-dihydroxyphenyl)-8-dimethylpyrano [8, 7-e] chroman) was found to be an antifungal component in the OEL and its fungicidal effect was confirmed. In order to prevent fungicaused spoilage, the possibility of adding glabridin or a licorice preparation made from OEL to tea beverages was suggested.