Microbiological contamination inside rubber ducks floating in the bathtub at a "duck bath" of a bathing facility was analyzed by examining bacterial and amoebic counts. The results of microbial tests, such as standard plate count, heterotrophic plate count and Legionella-LAMP (Loopmediated isothermal amplification) , showed that microbial contamination increased in the rubber ducks over time. When the ducks were washed with sodium hypochlorite, those microbial contaminations were not detected; but when the ducks were washed with an electrolyzed water, the standard plate counts and the heterotrophic plate counts were detected in the amount of 10³ per duck in the wipe samples. Without proper washing of rubber ducks, bacteria and free-living amoeba can grow and colonize biofilms, and can thereby cause infection in humans. Also, microbial contamination inside ducks may reduce chlorination of the entire bathtub and cause bacterial infection such as Legionellosis from the bathtub water.

The effect of combined use of alkaline electrolyzed water （AlEW） on the reduction of heat resistance of bacterial spores by high hydrostatic pressure processing（ HPP） was investigated in this study. No reduction of heat resistance of bacterial spores, which was defined as the spore survival by heat treatment at 80℃ for 15 min, was observed by the treatment of single HPP with 30MPa at 50℃ even for 6 hours. However, a 3-log decrease in the viable bacterial spores was obtained by the combination of AlEW pretreatment with 1 hour of HPP treatment. An additional 2 hours duration of HPP treatment could inactivate more 2 logs of the viable bacterial spores. The obtained D value of bacterial spores treated by HPP was decreased to one-eighth by the pretreatment with AlEW when compared with the control sample. In case of the temperature during HPP treatment was 70℃, bacterial spores did not reduce its heat resistance with lower pressuring levels. In case of the temperature during HPP treatment is high with lower pressure levels, bacterial spores did not reduce its heat resistance even when AlEW was combined as the pretreatment. It was considered that the decrease in heat resistance by AlEW was resulted from the weakening of surface layer of spores by protein dissolution with alkaline substance. No clear effect of high negative redox potential, which is a unique property of AlEW, on the reduction of heat resistance was recognized.

Pathogenic marine fungi, Lagenidium thermophilum is known causative agent in the crustacean industry. Current disinfection practice in hatchery has risks and negative impacts which prompts suitable substitute to synthetic antifungal agents. Thus, this study was conducted to evaluate the antifungal potential of postbiotic from four potential probiotics towards marine oomycetes, L. thermophilum IPMB 1401. The screening test showed that the Lactobacillus plantarum GS12 and Bacillus cereus GS15 postbiotics were positive for antifungal activity on L. thermophilum IPMB 1401. These two bacterial extracts have minimum inhibitory concentration （MIC） at 50%. The toxicity assay on MIC level of the postbiotic revealed that the cumulative mortality of brine shrimp nauplii exposed to B. cereus postbiotic was significantly lower compared to L. plantarum GS12 postbiotic and formalin. This indicates a high potential of B. cereus GS15 as a prospect for alternative control method for fungal infections in the crustacean culture industry.

Influenza outbreaks at geriatric long-term care facilities (g-LTCFs) can be deadly and their prevention is important. However, the factors influencing disease transmission in g-LTCFs remain controversial. In this descriptive study, we tried to identify the potential risk factors influencing influenza outbreaks that occurred in different influenza seasons within a single g-LTCF with 100 residents in Gunma Prefecture. We reviewed the detailed facility records for all influenza cases in both residents and staff between January 2012 and June 2020. Facility preventive measures were also reviewed. We found that community meals may have been a potential source of transmission leading to the outbreaks. When influenza infection is noted, implementation of strict preventive measures and restriction of meal provision to resident rooms may help to prevent disease transmission and the development of an outbreak. Such measures may also be useful to prevent the transmission of other serious droplet-borne diseases within g-LTCFs.

The microcolony formation at 30℃ on an enriched minimal salts agar plates by individual Escherichia coli cells heated at 50℃ was monitored with a time-lapse shadow image analysis system, MicroBio μ3D^TM AutoScanner. While the time course of microcolony count detected every half an hour for the unheated cells seemingly demonstrated a normal distribution, that for the heated cell population demonstrated totally the growth delay probably resulting from cell injury and also interestingly distributed in its rather deformed pattern with a tailing. Those patterns of the cumulative counts of appearing microcolonies during the post-heating cultivation period were expressed in three different mathematical models. This approach may be proposed as a rapid cultivation method predictable for enumeration of viable and repairable injured cells in practical use.

Benzo［a］pyrene (BaP) is one of the strongest carcinogenic compounds among polycyclicaromatic hydrocarbons (PAHs) .We previously identified the ITB9 strain of Olleya species, which shows BaP-degrading activity; our report was the first about BaP degradation by the genus Olleya. In this study, BaP-degradation efficiency by ITB9 was about 50% when the strain was suspended in 20 ml of L9 liquid medium with 100 μg/ml BaP and 0.2 M NaCl, with pH 8.0, and incubated at 25℃ for 5 days. Under the same conditions, all four type strains (O. marilimosa CIP108537, O. aquimaris KCTC22661, O. namhaensis KCTC23673, and O. algicola KCTC22024) also showed BaP-degrading activities, at efficiencies ranging from 49% to 63%. Olleya sp. ITB9 and O. aquimaris KCTC22661 were found to be in the same clade in the phylogenetic tree of the genus Olleya, given that the homology of 16S rRNA gene sequences between ITB9 and KCTC22661 was 99.77%.

　Two Bacillus strains were screened and identified using 16S rRNA gene sequencing the phenotypic tests, and then characterized in vitro for the probiotic characteristics. They were able to tolerate pH 2.5 for 2.5 h, following 0.3% bile salts and 0.1% pancreatin treatment for 5 h. They exhibited good ability to attach to intestinal epithelial cells and were susceptible to most of the antibiotics and being killed by several. Further and more important, they showed good proteolytic activity to food protein as gelatin and milk, with even higher activity than the reference strain. Thus, these two Bacillus strains are considered as potential proteolytic probiotic strains to food proteins.