This study aimed to compare and assess residual microorganisms and organic materials on selected dental instruments after practicing two infection control methods, including the standard protocol. Scaler tips (ST) , 3-way syringe tips（3ST) , Bristle brushes（BB) , and Rubber cups（RC) were collected and grouped into Standard (Group S) and Non-standard (Group N) for processing. In ST and 3ST, Group S was cleaned and autoclaved, while Group N was disinfected. For BBs and RCs, Group N was cleaned and autoclaved, and new instruments were used as Group S. To confirm the presence of residual microorganisms, instruments from each group were incubated in liquid and solid medium. The generated colonies on solid medium were identified at the species level by polymerase chain reaction (PCR) . To confirm the presence of residual organisms, each instrument was stained with Phloxine B and observed using a stereomicroscope. Only ST（8.0%) and 3ST (28.0%) samples from Group N were detected with residual microorganisms. The identified colonies included Staphylococcus, Cupriavidus, and Streptococcus spp. Residual organics were observed in all samples from Group S and N. These findings highlight the limitations of cleaning followed by autoclaving and especially disinfection in completely eradicating all microorganisms and organics.

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Consumer products such as detergents, fabric softeners, and cosmetics are typically used in various environments. Manufacturers must ensure the quality of products and ensure their safety through their lifecycle, from manufacturing to usage. Preservation efficacy testing (PET) is typically conducted to determine the preservative of a product prior to use. However, PET is time-consuming and laborious due to its long-term storage and culture-based detection methods. In this study, we focused on the metabolic activities of microorganisms and developed a rapid alternative to PET. We observed that 72 h of preservation was sufficient to predict preservation efficacy using the metabolic activity method. Finally, the accuracy of the metabolic activity method was compared to that of PET using a variety of products such as detergents and cosmetics. The accuracy of this alternative method exceeds 85% for highly fluid and easy-to-handle samples. These results suggest that the developed metabolic activity method possesses the potential to determine the preservative efficacy of products in only four days（72 h of preservation and 24 h of detection）. Thus, this method possesses the potential to provide a rapid and simple alternative to PET.

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This study aimed to investigate the bactericidal effect of ethanol-soluble lignin (ESL) from rice straw under ultraviolet-A (UV-A) irradiation. Following steam explosion pretreatment of rice straw, ethanol extraction was used to separate the lignin. The total phenolic content (TPC) in the ESL was 258 mg/g (gallic acid equivalent). Under UV-A irradiation, ESL exhibited bactericidal activity against Gram-positive and -negative bacteria at ≤10 mg TPC/L. Fluorescence experiments demonstrated significant adsorption of ESL to the cell surface of Staphylococcus aureus. Scanning electron microscopy revealed membrane deformation, producing many vesicles on the cell surface, when the ESL was activated by UV-A irradiation. These morphological changes were associated with an increase in membrane permeability, which elevated cell counts stained with propidium iodide to 51% and resulted in a 57% decrease in the intracellular ATP level. ESL exposed to UV-A light generated hydrogen peroxide. Addition of a scavenger of reactive oxygen species (ROS) or replacement of dissolved oxygen with argon gas in a bacterial suspension significantly suppressed the synergistic bactericidal activity of ESL and UV-A radiation, indicating that ROS are involved in the bactericidal mechanism. Organosolv lignin pretreated using steam explosion can be developed for antimicrobial application in combination with UV-A irradiation.

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In this study, the malodor detection method was constructed in our laboratory using bacteria isolated from washed fabrics and some effective disinfection techniques for suppressing malodor emitted by the isolates were evaluated. Bacterial isolates from a previous study (Okuda et al. 2025) were incubated on cotton fabric in basal salt medium containing glucose, casamino acids and squalene (BSM+C) . The intensity of malodor from the incubated fabric was evaluated by a sensory method on a six-point odor intensity scale. Fabric cultivated with each isolate emitted noticeable malodor. Sulfur compounds, short-chain alcohols and short-chain ketones were detected in cultivated fabrics using GC/MS analysis. Pretreatment before cultivation with heat or benzalkonium chloride reduced odor intensities, whereas those using ultrasonication or didecyl dimethyl ammonium chloride sustained high odor intensities. These results indicate that not only bacterial cell death but also enzyme denaturation or inactivation derived from them may be important to suppress malodor emission.

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We compared the results of Legionella pneumophila detection in cooling tower water samples using Legiolert and the conventional plate culture method. Both 1 mL and 10 mL volumes of cooling tower water samples were analyzed using Legiolert. The concordance rate of the Legiolert-1 mL test and the plate culture method was 86.7%. The Legiolert-10 mL test and the plate culture method showed 85.0% concordance. Legiolert would be effective for hygiene control in cooling towers because it can easily detect viable L. pneumophila in cooling tower water and produces results comparable to the conventional plate culture method.

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CAT agar plates, which contain cycloheximide, amphotericin B and thiabendazole as antifungal agents and vancomycin and polymyxin B as antibiotics, are selective agars with enhanced selectivity for Legionella detection, but preparation of these plates is not easy. We have therefore developed a CAT additive that produces CAT agars by simply spreading the additive on GVPC agars. GVPC agars that had been spread with the CAT additive performed as well as or better than CAT agars in detecting Legionella in concentrated stock samples of environmental water. The CAT additive would be effective for Legionella testing such as in cooling tower water samples, which are often contaminated with non-target microorganisms, and for retesting when Legionella cannot be detected due to the effects of contamination by non-target microorganisms.

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