A practical method to evaluate the deodorant efficacy was proposed in order to study the relationship between the antimicrobial activity and the deodorant efficacy of metal-treated cotton socks. The cell counts of bacteria and fungi on treated-socks were respectively decreased to 1/100 - 1/1000 and 1/10 - 1/100 of the initial cell counts. Actual wear tests indicated that metal-treatment was effective in inhibiting the growth of microorganisms. The antimicrobial activity of metal-treated socks was 1.0 - 1.9 times greater than that of commercial antimicrobial-deodorant socks after being worn. Correlation between bacterial cell counts and the odor intensity which was measured by a semiconductor odor sensor was found to be (p < 0.01). The correlation coefficients of metal-treated socks and untreated socks were 0.826 and 0.814, respectively. In contrast, little correlation for metal-treated socks and untreated socks with regard to fungi was observed. These findings suggest that bacteria contribute to the occurrence of the malodorous components and the odor sensor measurement method could play an important role in evaluating the deodorant efficacy of antimicrobial-deodorant finished textile fabrics.
The antibacterial activity of cotton fabrics chemically modified by some metal salt (metal ions) such as Cu 2 +, Fe 2 +, Fe3 + and Zn 2 + was investigated. The increase of the amount of adsorbed metal and the increase of anhydrous succinic acid concentrations was correlated. Zn 2 + ion-adsorption was the highest, followed by Fe 2 +, Cu 2 + and Fe3 + with the same amount of anhydrous succinic acid. The antibacterial activity of Cu 2 +-treatment against Staphylococcus aureus was the most effective. Zn 2 +-treatment possessed a great antibacterial activity against S. aureus even when the amount of adsorbed metal was the lowest. Cotton fabric treated with Cu 2 + possessed the most effective antibacterial activity againstKlebsiella pneumoniae and that treated with Zn 2 +, Fe 2 + and Fe3 + possessed a slight antibacterial activity. The antibacterial activity of 4 kinds of metal-treated fabrics was higher than that of commercial antibacterial and deodorant fabrics, when the amounts of anhydrous succinic acid used was more than 1.0 g/g fabric. In particular, the Cu 2 +treatment on cotton fabrics was more effective than that of commercial treatments. These findings suggest that antibacterial activity could be improved by treatment with metal salt on cotton fabrics.
Thermal inactivation patterns of spores of a mesophilic mold, Aspergillus niger, in capillaries heated at 66-55°C were studied. Thermal inactivation curves of A. niger spores in capillaries consisted of a shoulder and a linear decline at 66-57°C, whereas curves at 56 and 55°C consisted of a shoulder, a linear decline, and a sloping tail. The Arrhenius plot of the inactivation rate for the linear decline portions in inactivation curves was a broken line at around 57°C. The logarithm of the duration of the shoulder to the temperature was linear.
When Escherichia coil cells were treated with 20-40% (v/v) ethanol solution, there was an increase in intracellular concentration of hydrogen peroxide accompanied by a decrease in the survival rate of the cells. Several mutants with higher catalase activity were more resistant and some other mutants with lower catalase activity were more sensitive to ethanol treatment than the parent strain K12. The concentration of hydrogen peroxide in the ethanol-treated E. coil K12 cells was 20 to160 times higher than that in the untreated cells. The catalase-gene kat E', kat G, and kat E cloned strains, having higher catalase activity, were more ethanol-resistant than E. coil K12, recipient strain UM1 and UM1 charomid 9-28. For the bactericidal mechanism of ethanol, it is suggested that ethanol treatment might cause some damage to the cellular aerobic respiratory system and as a result, hydrogen peroxide may be generated to result in cell death.
According to negative-staining electron microscopic observations, ethanol-sensitive Escherichia coil phages, ES1 and ES2, treated with 30% (v/v) ethanol, exhibited contraction of the tail sheath and released nucleic acids from the phage head shell. When these phages were treated with 50 or 90% (v/v) ethanol solutions, desorption of tail, contraction of the tail sheath and absence of DNA in the head shell were detected. Correlations were found between these phenomena and the survival rate of phages ES1 and ES2 treated with ethanol. In the ethanol-tolerant E. coil phages, ER1 and ER2, these phenomena were not observed by electron microscopy after treatment with 30% (v/v) ethanol and some of these phenomena to a small degree and no contraction of tail sheath could be observed after treatment with 70% (v/v) ethanol.
The effect of heat treatment on the inactivation of Bacillus stearothermophilus IFO12550 spores by low hydrostatic pressure (LHP: 10-100 MPa) was studied. There were optimum temperatures in the inactivation of spores at 10, 20, 30 and 40 MPa. On the other hand, there was no optimum temperature in spore inactivation at 50, 60 and 100 MPa, and inactivation was dependent on the treatment temperature. The PD value at 30 MPa was at a minimum at 75°C compared with at other temperatures. Thus, hydrostatic pressure below 40 MPa was effective in inactivating the bacterial spores by LHP treatment at optimum temperatures.
To investigate oleic acid biodegradation, 7 strains of Aspergillus niger were tested with 3 different types of Czapex-Dox broth (CzDB) medium containing oleic acid, and their metabolic abilities to decompose the fatty acid into carbon dioxide and water were compared. When the fungal strains were grown in the CzDB media with both 14C-labeled and non-labeled oleic acid, A. niger YMC 0100 and YMC 0322 oxidized more than 58% of the supplied substrate within 72 h. The addition of saccharose as an additional carbon source substantially reduced the biodegradation of oleic acid to the point that all the strains showed less than 4% degradation.
For detection of verocytotoxin-producing Escherichia coil (VTEC) O157 in foods and feces, colony isolation on selective agar after immunomagnetic separation (IMS) was followed by polymerase chain reaction (PCR) assay. It was shown that Rainbow agar O157 could recover E. coli O157 more sensitively than other selective media such as Desoxycholate agar, DHL agar, SIB agar, CT-SMAC agar, BCM O157, Chrom agar O157 and Chrom agar E. coli. Also, the PCR assay of the typical colonies developed on Rainbow agar O157 was able to detect VTEC O157 in sample suspensions with more than 101 cfu/ml.
A total of 75 locations in 26 houses were examined for fungal contamination. Sixteen genera from 68 locations were detected. Cladosporium was the dominant contaminant. A high frequency of contamination was seen to involve Cladosporium, of which C. sphaerospermum and C. cladosporioides were detected most frequently at rates of 63.6% and 14.6%, respectively.
The effect of Prunus mume Sieb. et Zucc.(Prunus mume) extract on the production of verotoxins by enterohemorrhagic Escherichia coli O157: H7 (EHEC) was investigated. The amount of vero-toxins (ng/ml) produced was calculated and revised according to the ratio between the amount of vero-toxins detected in the test tube and the viable cell numbers of EHEC. Production of EHEC vero-toxins was inhibited by the extract of the fruit of Prunus mume at 156 mg/ml. This inhibitory effect was obtained at a dose below the minimal inhibitory concentration (625 mg/ml) of the Prunus mume extract, indicating that this extract seems to act on the vero-toxin-producing cells of EHEC before vero-toxins are produced.
The antibacterial activity of green tea extract was investigated on 36 isolates of pathogens. The minimum inhibitory concentration of the extract against some isolates such as Escherichia coli O157: H7 was less than 250 μg/ml. The growth of the organism in culture broth was completely inhibited with 500 μg/ml of the extract. The organism was not detected by culturing on agar plates after 6 h incubation in phosphate buffered saline with 1, 000 μg/ml of the extract. It was observed by fluorescence microscopy and scanning electric microscopy that the cell membranes were damaged with 1, 000 μg/ml of the extract.