The ability of heated scallop-shell powder (HSSP) to work against Listeria sp. biofilm formed at a low temperature was investigated. A biofilm of L. innocua ATCC 33090 was grown on a glass plate at 15˚C for 15 days, then immersed in HSSP slurry. Following treatment, the disinfection ability of the HSSP against the biofilm was non-destructively quantified by conductimetric assay. The biofilm grown at 15˚C was less sensitive than that grown at 37˚C to HSSP treatment and alkaline treatment. The biofilm grown at 15˚C was completely deactivated by 30 min of HSSP treatment (10 mg/mL, pH 12.5). In contrast, after 30 min treatment with alkaline solution at pH 12.5 or sodium hypochlorite (100 ppm), the activity was reduced by only one order of magnitude. The disinfection efficacy of HSSP (10 mg/mL) against L. innocua is similar to or higher than that of sodium hypochlorite (200 ppm). Fluorescence microscopy validated the results of the conductimetric assay. Therefore, HSSP treatment is a potentially powerful alternative control agent against Listeria sp. biofilms that present hazards in the food industry.

Acanthamoeba castellanii, a ubiquitous organism in water environments, is pathogenic toward humans and also is a host for bacteria of the genus Legionella, a causative agent of legionellosis. Oakmoss, a natural fragrance ingredient, and its components are antibacterial agents specifically against the genus Legionella. In the present study, oakmoss and its components were investigated for their amoebicidal activity against A. castellanii ATCC 30234 and the inhibitory effect on the uptake of L. pneumophila JCM 7571 (ATCC 33152) into A. castellanii. The oakmoss and its components 3-hydroxy-5-methylphenyl 2,4-dihydroxy-6-methylbenzoate(5), and 6,8-dihydroxy-3-pentyl-1H-isochromen-1-one (12) exhibited high amoebicidal activity (IC50 values; 10.5 ± 2.3, 16.3 ± 4.0 and 17.5 ± 2.8 μg/mL, respectively) after 48 h of treatment, which were equivalent to that of the reference compound, chlorhexidine gluconate. Pretreatment of L. pneumophila with sub-minimal inhibitory concentration of oakmoss, compound 5, 3-hydroxy-5-methylphenyl 2-hydroxy-4-methoxy-6-methylbenzoate (10) and 8-(2,4-dihydroxy-6-pentylphenoxy)-6-hydroxy-3-pentyl-1H-isochromen-1-one (14) obviously reduced the uptake of L. pneumophila into A.castellanii (p < 0.05).The inhibitory effect of compound 5 on the uptake of L. pneumophila was almost equivalent to that of ampicillin used as a reference. Thus, the oakmoss and its components were considered to be good candidates for disinfectants against not only genus Legionella but also A. castellanii.

Sanita-kun(TM) SA for Staphylococcus aureus (SkSA), a novel dry sheet quantitative culture system, was evaluated. When the inclusivity and exclusivity of SkSA were assessed using 121 microorganisms including 47 S. aureus strains, the tested S. aureus strains formed blue-colored colonies on the SkSA and all the other microbes failed to grow. The SkSA was then compared with Baird-Parker agar (BP) according to ISO 6888-1, Mannitol salt agar with egg yolk (MSEY), and 3M Petrifilm(TM) STX (3M-STX) in 100 artificially contami nated food samples. The correlation coefficients between SkSA and BP, SkSA and MSEY, and SkSA and 3M-STX were 0.971, 0.989 and 0.996, respectively. Our results demonstrated that SkSA is a suitable alternative for the enumeration of S. aureus in foods.

To clarify the availability of the dielectrophoretic impedance measurement (DEPIM) system as the evaluator for oral care, we evaluated the usefulness of DEPIM system by comparison with the standard plate counting (SPC) method. First, the relationship between the DEPIM results and bacterial concentration measured by SPC was clarified. Next, the measurement of the microorganism number in a mixed suspension was evaluated with DEPIM and SPC. The bacterial counts with DEPIM strongly correlated with those with SPC (r(2)=0.633-0.997) and this correlation was also shown in the measurement of a mixed bacterial suspension (ranging from 10(5) to 10(8) cfu/ml) of two bacterial species. Moreover, the experiments using dissociating enzymes to eliminate the influence of the size of the bacterial aggregates demonstrated that the microbial measurement results with DEPIM are unaffected by bacterial aggregates. This study demonstrated that bacterial counts with DEPIM strongly correlated with those with SPC and were unaffected by bacterial aggregates.

Kudoa septempunctata in olive flounder meat was inactivated using 3 distinct freezing methods：liquid freezing for 5 min, air blast freezing at －30℃ for 5 h, and －80℃ for 1 h. The fracture curve of olive flounder meat subjected to liquid freezing resembled that of meat stored at 4℃, indicating that the structure of olive flounder muscle was well preserved. In contrast, air blast freezing induced the disappearance of the fracture point in the fracture curve, indicating that there was deterioration in the meat quality. Liquid freezing preserved the transparency of olive flounder meat to the same degree as that of meat stored at 4°C. However, air blast freezing induced meat cloudiness. These results indicate that liquid freezing can be used for K. septempunctata inactivation without affecting the meat quality.

Bacillus cereus is a spore-forming bacterium. B. cereus occasionally causes nosocomial infections, in which hand contamination with the spores plays an important role. Therefore, hand hygiene is the most important practice for controlling nosocomial B. cereus infections. This study aimed to determine the appropriate hand hygiene procedure for removing B. cereus spores. Thirty volunteers' hands were experimentally contaminated with B. cereus spores, after which they performed 6 different hand hygiene procedures. We compared the efficacy of the procedures in removing the spores from hands. The alcohol-based hand-rubbing procedures scarcely removed them. The soap washing procedures reduced the number of spores by more than 2 log10. Extending the washing time increased the spore-removing efficacy of the washing procedures. There was no significant difference in efficacy between the use of plain soap and antiseptic soap. Handwashing with soap is appropriate for removing B. cereus spores from hands. Alcohol-based hand-rubbing is not effective.

Kudoa septempunctata is the causative agent of a foodborne disease associated with the consumption of raw Paralichthys olivaceus (olive flounder). Chickens were used to establish specific antibodies against K. septempunctata spores. A specific antiserum, CS#3, raised against sonicated spores, also recognized intact spores. The CS#3 antiserum showed high titers for sonicated and intact K. septempunctata spores and was suitable for both ELISA and immunohistochemical staining. Using homogenated raw olive flounder meat, the ELISA system detected more than 5.0×10(5) spores in 1 g of tissue, which was consistent with the number determined by microscopic examination. The preparation of rapid detection kits for K. septempunctata spores in P. olivaceus muscle tissue using immunochromatography with CS#3 antiserum should be useful for preventing the foodborne disease in the field.

Growth prediction of a four-strain cocktail of Salmonella Enteritidis in commercial products of pasteurized and unpasteurized liquid whole egg was studied with the new logistic model that we developed. The growth data of the pathogen in the liquid egg products at constant temperatures in our recent study (Sakha and Fujikawa, Biocont. Sci., 2012) were used for prediction. With estimated values of the parameters in the model, it successfully predicted the Salmonella growth in the liquid egg products at dynamic temperature conditions in the high and low ranges. The Baranyi model, which is well known worldwide, could predict Salmonella growth in the pasteurized product at the dynamic temperature conditions in the high range only. This study would be, in our knowledge, the first report on the prediction of Salmonella growth in both pasteurized and unpasteurized liquid egg products at dynamic temperature conditions with a mathematical model.

The oxidative power of hydroxyl radicals has been applied to disinfection systems for the purpose of oral hygiene by utilizing blue light-induced photolysis of hydrogen peroxide (H₂O₂) in our laboratory. In the present study, the bactericidal potential of blue light-irradiated oxydol products via hydroxyl radical generation was compared with that of 3% (w/v) H₂O₂. Eleven commercially available oxydol products were used in the present study. Even though a few of the products that contained ethanol, a hydroxyl radical scavenger, as an additive showed slightly lower hydroxyl radical yield as compared with 3% (w/v) H₂O₂, the blue-light irradiation of each oxydol product for 3 min showed similar or superior bactericidal activity against Staphylococcus aureus to that of 3% (w/v) H₂O₂. The results strongly suggest that any of the oxydol products tested in the present study can be used as a source of hydroxyl radicals for the disinfection technique developed in our laboratory.

5a-h, a series of (5-substituted-2-methyl-1,3-thiazole-4-yl) acetic acids as heterocyclic acetic acid derivatives, was designed and synthesized from ethyl acetoacetate. The synthesized compounds were screened for their antimicrobial activities against bacterial and fungal strains, and their characteristics were investigated by assays under various temperature and pH conditions. Cytotoxicity was evaluated with the use of sheep erythrocytes and human neonate dermal fibroblasts. Similarly, agents such as lauric acid 6 and parabens 7a-b, which are used as preservative agents for commercial cosmetics and detergents, were assayed for comparison. Although the structure of 5a is simple, comprising a thiazole attached with an octyl group and acetic acid moiety, the compound showed stronger and broader antibacterial and antifungal activities among the 5 series against the tested microbes other than gram-negative bacteria. Interestingly, 5a overcame the weak antifungal activity of parabens 7a-b. Also, the cytotoxicity of 5a was less than that of parabens 7a-b, especially to human dermal fibroblasts. These results suggest that thiazolyl-acetic acid 5a is a potentially effective biocide, and that it could be used as a preservative agent in commercially sold cosmetics and detergents, facilitated by the hydrophilic and charge properties of its carboxylic acid moiety.