• Journal of dental hygiene science
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• v.24 no.1
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• pp.54-61
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• 2024

Background: The Korean name for Angelica gigas Nakai (AGN) is Cham-dang-gui, which grows naturally or is cultivated, and its dried roots are used in traditional herbal medicines. The AGN root exert various pharmacological effects. Despite the various pharmacological effects of the AGN root, there are no reports on its anti-oral microbial effects. The purpose of this study was to reveal the anti-oral microbial effect and the microbial and biochemical changes in oral microorganisms according to the concentration of the ethanol extract of AGN (EAGN) root, and to confirm the possibility of using EAGN as a plant-derived functional substance for controlling oral infectious microorganisms. Methods: Disk diffusion test, growth measurement, biofilm formation assay, and measurements of acid production and buffering capacity were performed to confirm the antibacterial effect of EAGN. Results: EAGN showed anti-oral bacterial effects against Streptococcus mutans and Aggregatibacter actinomycetemcomitans at all concentrations, with S. mutans showing a more susceptible effect at concentrations above 5.0 mg/ml and A. actinomycetemcomitans at 3.75 mg/ml. EAGN treatment significantly reduced A. actinomycetemcomitans growth at all concentrations tested. Biofilm formation was significantly reduced at concentrations above 3.75 mg/ml for S. mutans and 2.5 mg/ml for A. actinomycetemcomitans. Acid production in S. mutans and A. actinomycetemcomitans was significantly increased by treatment with EAGN, and the buffering capacities of S. mutans and A. actinomycetemcomitans increased from an EAGN concentration of 3.75 mg/ml and above. Conclusion: EAGN showed anti-oral bacterial effects against both S. mutans and A. actinomycetemcomitans at concentrations above 3.75 mg/ml, which were thought to be related to the inhibition of their growth and biofilm formation. Therefore, EAGN can be used as a safe functional substance derived from medicinal plants owing to its antibacterial effects against S. mutans and A. actinomycetemcomitans.

• Korean Journal of Food Science and Technology
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• v.49 no.2
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• pp.146-150
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• 2017

Staphylococcus aureus is a pathogenic bacterium that causes food poisoning, exhibits a strong capacity to form biofilm, and is highly resistant to antimicrobial agents. The purpose of this study was to investigate the antimicrobial characteristics of corosolic acid against S. aureus. S. aureus showed high susceptibility to corosolic acid in a concentration-dependent manner. The minimum inhibitory concentration and colony-forming ability determined by the broth microdilution method showed that corosolic acid had strong antimicrobial activity against the bacteria. The diameters of the inhibition zone and numbers of colony forming units at each concentration of corosolic acid were also measured. In addition, corosolic acid displayed potent biofilm inhibition activity against S. aureus at concentrations below its minimum inhibitory concentration. These results suggest that corosolic acid can be used to effectively prevent biofilm formation by S. aureus, thereby making S. aureus more susceptible to the action of antimicrobials.

• Membrane Journal
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• v.32 no.1
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• pp.23-32
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• 2022

Bacteria grow biofilm on various surface such as separation membrane, food packaging film and biomedical device. Growth of biofilm is associated with the formation of a complex structure of exopolysaccharides. Effect of antibacterial effect reduce drastically once the biofilm developed due to the difficulties in mass transport of antimicrobial agent. In order to enhance the antibacterial activity, surface of the membrane is modified, coated or immobilized with functional materials with biocidal properties. One of the idea is to introduce positive charge on the membrane surface by the presence of quaternary ammonium group which might displace divalent metal ion such as magnesium or calcium present in the bacteria cell wall. Efficacy of cell membrane disruption depends on the mobility of the agents available directly on the surface environment. In this review, various biocidal agents like quaternary ammonium group, helamine or zwitter ion containing membrane are discussed.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.81-87
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• 2006

The industrial systems contain many sites and components susceptible to biofilms formation. Biofilms play an important role in microbial growth and industrial fouling. Thus, the control of the biofilms in industrial systems has been emphasized, however, the efficient controlling method was not provided yet. Since silver compounds have no residual and corrosion problem, the interest for silver compounds as a biofilm control disinfectant has been increased. In this study, we attempted to examine the disinfection ability of silver compounds. The disinfection efficiency of two silver compounds(silver ion and silver oxide) were evaluated for biofilms in comparison with suspended cells using well known indicator microorganisms(E. coli, P. aeruginosa) and compared with that of chlorine. Silver compounds were found to be effective in inactivating E. coli and P. aeruginosa biofilms. The reason for superiority of silver compounds as biofilm disinfectant was suggested by that silver can penetrate into the inner biofilm matrix faster than chlorine without consumption. This study reports that the disinfectant which is highly effective in inactivating the suspended cells in water becomes the less effective for controlling biofilm because of its high reactivity. This results imply that the effective strategy for biofilm control can be achieved by considering thoroughly the chemical nature of disinfects and biofilm structure and the reactivity between them.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.355-363
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• 2015

The present work quantified the growth of young biofilm in a model distribution system that was fed with chlorinated drinking water at a hydraulic retention time of 2 h. Bacterial biofilms grew on the surface of polyvinyl chloride (PVC) slides at a specific growth rate of $0.14{\pm}0.09day^{-1}$ for total bacteria and $0.16{\pm}0.08day^{-1}$ for heterotrophic bacteria, reaching $3.1{\times}10^4cells/cm^2$ and $6.6{\times}10^3CFU/cm^2$ after 10 days, respectively. The specific growth rates of biofilm-forming bacteria were found to be much higher than those of bulk-phase bacteria, suggesting that biofilm bacteria account for a major part of the bacterial production in this model system. Biofilm isolates exhibited characteristic kinetic properties, as determined by ${\mu}_{max}$ and $K_S$ values using the Monod model, in a defined growth medium containing various amounts of acetate. The lowest ${\mu}_{max}$ value was observed in bacterial species belonging to the genus Methylobacterium, and their slow growth seemed to confer high resistance to chlorine treatment (0.5 mg/L for 10 min). $K_S$ values (inversely related to substrate affinity) of Sphingomonas were two orders of magnitude lower for acetate carbon than those of other isolates. The Sphingomonas isolates may have obligate-oligotrophic characteristics, since the lower $K_S$ values allow them to thrive under nutrient-deficient conditions. These results provide a better understanding and control of multi-species bacterial biofilms that develop within days in a drinking water distribution system.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.4
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• pp.438-443
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• 2018

The emergence of biofilms have generated urgent alarm in clinical and medicine manufacturing fields engaged in the search for novel antimicrobials from ethno-medicinal plants. The National Institutes of Health (NIH) has estimated that 70% of all microbial infections in the world are associated with biofilms. In addition, the emergence of strains resistant to conventional antibiotics has become a serious threat to global public health. Therefore, finding alternative medicines is a major issue in the field of integrative medicine. In this study, four different herb extracts were screened for biofilm formation and the activities of Klebsiella pneumoniae. Of them, Scutellaria scordifolia Fisch. ex Schrank extracts had inhibitory effects on bacterial growth and biofilm formation. The Scutellaia scordifolia Fisch. ex Schrank extracts did not cause any cytotoxicity to L929 cells. The growth of K. pneumoniae was inhibited compared to other comparators in the experimental group containing Scutellaia scordifolia Fisch. ex Schrank. In a group of experiments with plant extracts, a maximum of 60 times the level of living bacteria was confirmed compared to the controls without the addition of the Scutellaia scordifolia Fisch. ex Schrank extracts. In a group of experiments with a significantly lower level of fluorescence extraction, differential interference contrast imaging showed that the number of K. pneumonae was reduced. These results suggest that extracts of this plant be applied as antimicrobial agents against K. pneumoniae, particularly in biofilm forms.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.4
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• pp.406-415
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• 2020

Silver diamine fluoride (SDF) is an effective and efficient agent for arresting dental caries. It can be useful in treating children with behavioral or medical limitations. The purpose of this study was to evaluate the antimicrobial effect of SDF by using salivary biofilm. Pellicle-like saliva coated structure was prepared by using unstimulated saliva. For developing cariogenic biofilm, Streptococcus mutans was added to the mixture of pooled saliva and inoculated into a saliva coated glass or chamber. SDF was applied to cariogenic biofilm to evaluate the antimicrobial effect of SDF. As time passed, total bacteria and S. mutans were reduced after application of SDF (p < 0.000). Confocal laser scanning microscope also showed the increment of the ratio of dead cell. As a result of experiment using enamel and dentin of primary teeth, it was confirmed that the growth of cariogenic biofilm was inhibited when the SDF was treated (p = 0.029 each). This study showed excellent anti-microbial effect of SDF. And anti-caries effect in clinical practice can be expected.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.2
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• pp.163-170
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• 2021

This study was conducted to create a technology to remove acne bacteria with human-friendly materials. First, the Cutibacterium acnes (C. acnes) were adsorbed to the mica disc to grow, and then the biofilm was checked through an atomic microscope to see if the biofilm had grown. Based on the topographic image, the shape changed round, the size was 17% longer on average, and the phase value of the resonance frequency separating materials was observed as a single value, the biofilm grown by covering the extracellular polymeric substrate (EPS). As a result of processing 50 mM of amino acids in the matured biofilm, the concentration of C. acnes decreased when valine, serine, arginine and leucine were treated. Scanning with nanoindentation and AFM contact modes confirmed that the hardness of biofilms treated with Valine (Val) increased. This indicates that an AFM tip measured cell which may have more solidity than that of EPS. The experiment of fluorescent tagged to EPS displays an existence of EPS at the condition of 10 mM Val, but an inhibition of growth of EPS at the 50 mM Val. Number of C. acnes was also reduced above 10 mM of Val. Weak adhesion of biofilm generated from an inhibition of EPS formation seems to induce decrease of C. acnes. Accordingly, we elucidated that Val has an efficiency which eliminates C. acnes by approach of an inhibition of EPS.

• Journal of Life Science
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• v.33 no.11
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• pp.936-943
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• 2023

This study was conducted to investigate the potential of Stewartia koreana as anti-microbial materials. The branches, stems and leaves of S. koreana were extracted into 70% ethanol and their antibacterial activity against P. aeruginosa was confirmed. The leaf, branch and stems extracts (1 mg/disc) showed the antibacterial activity against P. aeruginosa and leaf extracts showed higher antibacterial activities than those from branch extracts. The MIC against P. aeruginosa was 0.8 mg/ml and showed bacteriostatic action. The inhibitory effects of extract on biofilm formation and gene expression related to biofilm formation of P. aeruginosa was determined by biofilm biomass staining, SEM and qRT-PCR analysis. The biofilm biomass and cell growth of P. aeruginosa in the cultures treated with 0.2~2.0 mg/ml of S. koreana leaf extracts were significantly decreased in a concentration-dependent manner. We observed that the extract had an inhibitory effect on the formation of P. aeruginosa biofilms at concentrations of 0.8 mg/ml by SEM. qRT-PCR analysis showed that the lasI and rh1I gene expression associated to quorum sensing (QS) in the cultures treated with 0.2~2.0 mg/ml of S. koreana leaf extracts were suppressed in a concentration-dependent manner. Based on the above results, it can be concluded that S. koreana leaf extracts can be used as anti-microbial material derived from natural materials, as demonstrated by the antibacterial action and inhibition of biofilm formation of P. aeruginosa by QS inhibition.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.779-781
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• 2010

After preliminary tests indicated an increased number of heterotrophic bacteria, we investigated possible sources of contamination in a neonatal intensive care unit (NICU) water distribution system. Scanning electron microscopic examination of flexible metallic hoses associated with the system revealed the presence of a biofilm; partial 16S rDNA sequencing revealed that the biofilm contained Blastomonas natatoria. Purgation of the water system three times a day, reinforced faucet cleaning, decreasing the cold water temperature to $12^{\circ}C$, and six repeated chlorinations at concentrations as high as 2 mg/l were not sufficient to eradicate the bacterial contamination. Replacing all of the rubber-interior flexible metallic hoses with teflon-lined hoses, followed by heating the water to $70^{\circ}C$, successfully controlled the bacteria.