Biocontrol science最新文献

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%.

Toilet malodor is one of the most concerned malodor in residential houses, so that many technologies and products have been developed by which is aiming to remove or reduce such toilet malodor. Toilet malodour is generated from human faecal matters left inside of toilet bowl and from that deposited outside of toilet bowl such as toilet floors. In order to remove or prevent the malodor generated outside of toilet bowl, it is effective to do more frequent cleaning of toilet room surfaces or place a deodorizer which mask the malodour by perfume. We developed a toilet deodorizer which is preventing malodor generation outside of toilet bowl more effectively by delivering antibacterial efficacy on toilet room permeable surfaces. We analyzed microbiological quality of residential toilet rooms and found that toilet floor is the most contaminated location by bacteria, so that we developed a test method using materials frequently used for residential toilet floors such as vinyl cushion and using bacteria commonly found in toilet room environment. As the results, we found the product can provide bacterial growth prevention efficacy on permeable materials and prevent toilet malodor effectively.

We previously identified a new Bacillus sporothermodurans strain, TM-I-3, which produces volatile compounds that show potent inhibitory activity against certain types of fungi, including Aspergillus fumigatus and Cladosporium cladosporioides. Non-contact antifungals derived from this bacterium may provide multidirectional inhibition and may be useful in disease prevention. This study is aimed at identifying the stage of fungal growth that is inhibited by TM-I-3 to elucidate the mechanism of its contact-independent antifungal activity. We evaluated mycelial growth and the gross fungal colony areas after 7 days in each experimental group varying the time in the proximity of TM-I-3 for 24 hours each. The fungal growth inhibition assay showed that TM-I-3 inhibited spore germination: the lag phase in the sigmoid growth curve. The present study demonstrated that TM-I-3 might be an effective fungistatic agent against pathogenic and allergenic fungi.

Bioshell calcium oxide (BiSCaO) is derived from scallop shells and after heat treatment exhibits broad microbicidal activity. BiSCaO Water is a disinfectant prepared by collecting the aqueous layer after adding BiSCaO powder to water, is colorless and transparent, and has a pH of 12.8. We compared the utility of commercially available BiSCaO Water, ethanol, sodium hypochlorite, hypochlorous acid and hydrogen peroxide solutions as sterilization agents to enable the reuse of surgical and N95 face masks. The microbicidal efficacy of each disinfectant was evaluated using pieces of surgical and N95 face masks contaminated with normal bacterial flora. The results suggest that BiSCaO Water has excellent disinfection activity toward contaminated polypropylene masks and has minimal adverse effect on the structure of non-woven masks.

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.

In the present study, the antifungal activity of metabolites produced by Bacillus atrophaeus B5 and a new Brevibacterium strain against Alternaria alternata was evaluated. Assays in vitro and in vivo on tomato fruit during postharvest were made. Based on the 16S rDNA gene sequence analysis, the new strain (strain B7) was identified as Brevibacterium frigoritolerans. Metabolites produced by both bacterial strains reduced the spore germination of A. alternata in vitro and decreased the severity of the alternaria rot disease on tomato fruit during postharvest. This is the first report that demonstrates the potential of B. frigoritolerans B7 as a biocontrol agent against this fungal phytopathogen. The use of metabolites produced by B. atrophaeus B5 and B. frigoritolerans B7 represents a new approach to reduce the use of chemical pesticides and control fungal decay during the postharvest stage.

To test the efficacy of chemical disinfectants against bacterial biofilms in hemodialysis equipment, a Center for Disease Control and Prevention (CDC)-Biofilm Reactor was used to create biofilms. Methylobacterium radiotolerance was isolated from the hemodialysis fluid and used as the test organism. We examined the efficacy of sodium hypochlorite (NaOCl) in elimination of planktonic cells compared to that in the case of biofilms. Planktonic bacteria were completely eliminated at 50 parts per million (ppm) of NaOCl, which is the lowest concentration for clinical use. The viable cell count in the biofilm reached its minimum value around a logarithmic reduction value (LRV) of 6, when the concentration was raised to 1000 ppm and the reaction time was extended by 1 hour or more. Furthermore, at 200 ppm, the LRV was elevated depending on the time. And the LRV while maintaining static conditions for 6 hours at 200 ppm was similar to that of short time at 1000 ppm. These results suggest that NaOCl has sufficient bactericidal activity even for biofilms at a practical concentration and reaction time, and that the CDC-Biofilm Reactor is an effective tool for finding useful disinfection conditions.

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.

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.

This pilot study aimed to characterize Riemerella anatipestifer from ducklings, testing their susceptibility to antimicrobial agents and to detect their virulence markers. Seven R. anatipestifer isolates with 11.67% infection rate were identified out of sixty freshly dead ducklings and confirmed by PCR assay targeting gyrB gene. The gyrB gene sequences of R. anatipestifer isolates were 100% identical to each other and also showed 100% sequence similarity to the published gyrB genes. Four virulence genes namely ompA, prtC, hagA, and sspA were identified in all isolates except sspA was detected in 5 isolates. The antibiogram revealed higher sensitive to imipenem, amikacin, and rifampin, while, a remarkably high resistance was displayed against ampicillin, penicillin, cefipime, trimethoprim/sulfamethoxazole, gentamicin, ceftazidime, streptomycin and cefoperazone. Proper and rapid identification of R. anatipestifer with detection of their antimicrobial susceptibility and its virulence potential is essential for understanding the epidemiology of R. anatipestifer and to apply the effective control strategies.