• Restorative Dentistry and Endodontics
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• v.46 no.2
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• pp.20.1-20.11
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• 2021

Objectives: The aim of this study was to evaluate bacterial nanocellulose (BNC) membranes incorporated with antimicrobial agents regarding cytotoxicity in fibroblasts of the periodontal ligament (PDLF), antimicrobial activity, and inhibition of multispecies biofilm formation. Materials and Methods: The tested BNC membranes were BNC + 1% clindamycin (BNC/CLI); BNC + 0.12% chlorhexidine (BNC/CHX); BNC + nitric oxide (BNC/NO); and conventional BNC (BNC; control). After PDLF culture, the BNC membranes were positioned in the wells and maintained for 24 hours. Cell viability was then evaluated using the MTS calorimetric test. Antimicrobial activity against Enterococcus faecalis, Actinomyces naeslundii, and Streptococcus sanguinis (S. sanguinis) was evaluated using the agar diffusion test. To assess the antibiofilm activity, BNC membranes were exposed for 24 hours to the mixed culture. After sonicating the BNC membranes to remove the remaining biofilm and plating the suspension on agar, the number of colony-forming units (CFU)/mL was determined. Data were analyzed by 1-way analysis of variance and the Tukey, Kruskal-Wallis, and Dunn tests (α = 5%). Results: PDLF metabolic activity after contact with BNC/CHX, BNC/CLI, and BNC/NO was 35%, 61% and 97%, respectively, compared to BNC. BNC/NO showed biocompatibility similar to that of BNC (p = 0.78). BNC/CLI showed the largest inhibition halos, and was superior to the other BNC membranes against S. sanguinis (p < 0.05). The experimental BNC membranes inhibited biofilm formation, with about a 3-fold log CFU reduction compared to BNC (p < 0.05). Conclusions: BNC/NO showed excellent biocompatibility and inhibited multispecies biofilm formation, similarly to BNC/CLI and BNC/CHX.

• Journal of Korean Academy of Dental Administration
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• v.6 no.1
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• pp.28-35
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• 2018

Halitosis is primarily caused by bacterial decay. The bacteria, which originate from biofilms such as dental plaque, show abnormal proliferation due to dental caries, periodontal diseases, soft tissue infections, and tongue diseases. Most studies on halitosis have exclusively focused on gram-negative bacteria in the oral cavity rather than on general oral microorganisms including oral fungi. This study analyzed oral fungal hyphae, as well as distribution and motility of oral microorganisms, and provided basic data on the control of halitosis. Our results revealed that the greater is the number of cocci bacteria, the higher is the halitosis value, or bad breath value (BBV), suggesting that cocci have a strongly positive correlation with halitosis (r=0.379, p=0.030). Moreover, there was no significant difference in the morphology or distribution of motile bacteria and motility score, with respect to BBV. Lastly, we investigated the relationship between halitosis and oral fungal hyphae. We found that a higher BBV corresponded with a greater number of fungal hyphae and that patients with fungal hyphae scored a higher BBV. However, this result was not statistically significant. In conclusion, this study provided the preliminary data on oral microorganisms and halitosis, but further studies are needed to analyze the relationship between oral microorganisms and halitosis.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1149-1161
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• 2023

Changes in the gut microbiome cause recolonization by pathogens and inflammatory responses, leading to the development of intestinal disorders. Probiotics administration has been proposed for many years to reverse the intestinal dysbiosis and to enhance intestinal health. This study aimed to evaluate the inhibitory effects of two newly designed probiotic mixtures, Consti-Biome and Sensi-Biome, on two enteric pathogens Staphylococcus aureus and Escherichia coli that may cause intestinal disorders. Additionally, the study was designed to evaluate whether Consti-Biome and Sensi-Biome could modulate the immune response, produce short-chain fatty acids (SCFAs), and reduce gas production. Consti-Biome and Sensi-Biome showed superior adhesion ratios to HT-29 cells and competitively suppressed pathogen adhesion. Moreover, the probiotic mixtures decreased the levels of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL)-6 and IL-1β. Cell-free supernatants (CFSs) were used to investigate the inhibitory effects of metabolites on growth and biofilms of pathogens. Consti-Biome and Sensi-Biome CFSs exhibited antimicrobial and anti-biofilm activity, where microscopic analysis confirmed an increase in the number of dead cells and the structural disruption of pathogens. Gas chromatographic analysis of the CFSs revealed their ability to produce SCFAs, including acetic, propionic, and butyric acid. SCFA secretion by probiotics may demonstrate their potential activities against pathogens and gut inflammation. In terms of intestinal symptoms regarding abdominal bloating and discomfort, Consti-Biome and Sensi-Biome also inhibited gas production. Thus, these two probiotic mixtures have great potential to be developed as dietary supplements to alleviate the intestinal disorders.

• Journal of Dairy Science and Biotechnology
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• v.41 no.4
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• pp.203-210
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• 2023

Bacterial contamination negatively affects the quality, functionality, and safety of dairy products. Adherent populations of bacteria, referred to as biofilms, grow on the surfaces of dairy processing equipment and are the primary cause of dairy contamination. In addition, microorganisms present in the farm environment and dairy factory can contaminate the Clear-In-Place (CIP) line through raw milk transport pipes; therefore, exhaustive management is required. In dairy manufacturing facilities, biofilm formation is controlled using CIP systems that primarily require sodium hydroxide and nitric acid. However, the leakage or incomplete removal of these potently active compounds can be harmful to humans. In the present study, we compared the eradication of Escherichia coli and other bacteria using commercially available combinations of sodium hypochlorite (NaClO) and citric acid, which are recognized by the Korean Ministry of Food and Drug Safety (MFDS) as food disinfectants. When considered in the CIP system of the field manufacturing process, E. coli was not detected (compared to detection before treatment), and other bacteria were detected at 0-32 culture-forming units (CFU)/cm². The residual amount of chlorine ions after CIP treatment was similar to that in tap water, and there was no significant difference in the overall components of the fermented dairy products. Therefore, the NaClO/citric acid CIP system can be safely applied in dairy manufacturing processes.

• Journal of Veterinary Science
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• v.25 no.1
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• pp.6.1-6.11
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• 2024

Background: Chronic bovine mastitis is linked to biofilm-producing Staphylococcus aureus (bp-Sa) or Staphylococcus coagulase-negative (bp-Scn). Objectives: Bp-Sa and bp-Scn were treated with intramammary preparations of either enrofloxacin HCl·2H₂O-dimethyl-sulfoxide-chitosan (enro-C/DMSO/chitosan) or enro-C alone. Their potential to inhibit and degrade biofilm formation in vitro was also assessed. Methods: Milk samples were obtained from the affected quarters in a herd. Phenotypical and genotypical identifications as biofilm-producing Staphylococcus species were carried out. Enro-C/DMSO/chitosan and enro-C alone were assessed to determine their in vitro efficacy in interfering with biofilm formation and their bactericidal effects. A prolonged eight-day treatment with a twice-daily intramammary insertion of 10 mL of enro-C/DMSO/chitosan or enro-C alone was set to evaluate the clinical and bacteriological cures on day 10 in 15 cows per group and the biofilm-inhibiting ability. Results: Fifty-seven percent of the isolates were identified as Staphylococcus spp., of which 50% were bp-Sa, 46% bp-Scn, and 4% Staphylococcus pseudintermedius. One hundred percent of the S. aureus isolated and 77% of Staphylococcus coagulase-negative were biofilm producers. In both groups, the icaA and icaD biofilm-producing genes were identified. The experimental preparation could inhibit biofilm formation, degrade mature biofilms, and have well-defined microbicidal effects on planktonic and biofilm bacteria. The respective clinical and bacteriological cure rates were 100% and 80% for enro-C/DMSO/chitosan and 41.7% and 25% for enro-C alone. Conclusions: Enro-C/DMSO/chitosan eliminates bp-Sa and bp-Scn from cases of chronic bovine mastitis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.2
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• pp.129-136
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• 2024

Lactic acid bacteria (LAB) growth in processed meat products produces slime. In this study, 10 different biofilm-forming LAB, including Leuconostoc mesenteroides, Lacticaseibacillus paracasei, Levilactobacillus brevis, Lactiplantibacillus plantarum, Leuconostoc citreum, Weissella viridescens, and Latilactobacillus sakei, were isolated from various meat products and identified based on 16S rRNA gene analysis. To inhibit biofilm formation by LABs, Eisenia bicycles methanolic extract (EB) and ethyl acetate soluble fraction (EA) were used as antibacterial and antibiofilm agents, respectively. Furthermore, EA and EB were employed to synthesize gold nanoparticles (AuNPs) such as EB-AuNPs and EA-AuNPs, which could serve as antibiofilm agents against the isolated LAB. These findings demonstrate that EA, EB-AuNPs, and EA-AuNPs exhibit significant antibacterial activity against the isolated LAB. Furthermore, EB-AuNPs reduced L. citreum biofilm production, whereas EA-AuNPs inhibited L. mesenteroides and L. brevis biofilm formation. The current results suggest that EB-AuNPs and EA-AuNPs can be used as nanomaterials to inhibit LAB that form biofilms on meat products.

• Journal of Veterinary Science
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• v.25 no.2
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• pp.30.1-30.16
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• 2024

Background: Biofilms, such as those from Staphylococcus epidermidis, are generally insensitive to traditional antimicrobial agents, making it difficult to inhibit their formation. Although quercetin has excellent antibiofilm effects, its clinical applications are limited by the lack of sustained and targeted release at the site of S. epidermidis infection. Objectives: Polyethylene glycol-quercetin nanoparticles (PQ-NPs)-loaded gelatin-N,O-carboxymethyl chitosan (N,O-CMCS) composite nanogels were prepared and assessed for the on-demand release potential for reducing S. epidermidis biofilm formation. Methods: The formation mechanism, physicochemical characterization, and antibiofilm activity of PQ-nanogels against S. epidermidis were studied. Results: Physicochemical characterization confirmed that PQ-nanogels had been prepared by the electrostatic interactions between gelatin and N,O-CMCS with sodium tripolyphosphate. The PQ-nanogels exhibited obvious pH and gelatinase-responsive to achieve on-demand release in the micro-environment (pH 5.5 and gelatinase) of S. epidermidis. In addition, PQ-nanogels had excellent antibiofilm activity, and the potential antibiofilm mechanism may enhance its antibiofilm activity by reducing its relative biofilm formation, surface hydrophobicity, exopolysaccharides production, and eDNA production. Conclusions: This study will guide the development of the dual responsiveness (pH and gelatinase) of nanogels to achieve on-demand release for reducing S. epidermidis biofilm formation.

• Journal of Microbiology and Biotechnology
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• v.34 no.2
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• pp.289-295
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• 2024

We have developed an aptamer that specifically binds to Porphyromonas gingivalis to reduce the cellular damage caused by P. gingivalis infection and applied it as a biosensor. P. gingivalis is one of the major pathogens causing destructive periodontal disease among the periodontal microorganisms constituting complex biofilms. Porphyromonas gingivalis G-protein (PGP) known to play an important role in the transmission of germs was used as a target protein for the screening of aptamer. The aptamer that has binds to the G-protein of P. gingivalis, was screened and developed through the Systemic Evolution of Ligands by Exponential Energy (SELEX) method. Modified-Western blot analysis was performed with the aptamer which consisted of 38 single-stranded DNA to confirm the selectivity. ELONA (enzyme linked oligonucleotide assay) used to confirm that the aptamer was sensitive to PGP even at low concentration of 1 ㎍/ml. For the rapid detection of P. gingivalis, we constructed a surface plasmon resonance biosensor with SPREETA using the PGP aptamer. It was confirmed that PGP could be detected as low concentration as at 0.1 pM, which is the minimum concentration of aptamer sensor within 5 min. Based on these results, we have constructed a SPREETA biosensor based on aptamer that can bind to P. gingivalis G-protein. It can be used as an infection diagnosis system to rapidly diagnose and analyze oral diseases caused by P. gingivalis.

• Journal of dental hygiene science
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• v.16 no.4
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• pp.284-292
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• 2016

Water supplied through dental unit waterlines (DUWLs) has been shown to contain high number of bacteria. To reduce the contamination of DUWLs, it is essential to develop effective disinfectants. It is, however, difficulty to obtain proper DUWL samples for studies. The purpose of this study was to establish a simple laboratory model for reproducing DUWL biofilms. The bacteria obtained from DUWLs were cultured in R2A liquid medium for 10 days, and then stored at $-70^{\circ}C$. This stock was inoculated into R2A liquid medium and incubated in batch mode. After 5 days of culturing, it was inoculated into the biofilm formation model developed in this study. Our biofilm formation model comprised of a beaker containing R2A liquid medium and five glass rods attached to DUWL polyurethane tubing. Biofilm was allowed to form on the stir plate and the medium was replaced every 2 days. After 4 days of biofilm formation in the laboratory model, biofilm thickness, morphological characteristics and distribution of the composing bacteria were examined by confocal laser microscopy and scanning electron microscopy. The mean of biofilm accumulation was $4.68{\times}10^4$ colony forming unit/$cm^2$ and its thickness was $10{\sim}14{\mu}m$. In our laboratory model, thick bacterial lumps were observed in some parts of the tubing. To test the suitability of this biofilm model system, the effectiveness of disinfectants such as sodium hypochlorite, hydrogen peroxide, and chlorhexidine, was examined by their application to the biofilm formed in our model. Lower concentrations of disinfectants were less effective in reducing the count of bacteria constituting the biofilm. These results showed that our DUWL biofilm laboratory model was appropriate for comparison of disinfectant effects. Our laboratory model is expected to be useful for various other purposes in further studies.

• Korean Journal of Microbiology
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• v.44 no.3
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• pp.244-250
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• 2008

To evaluate bacteriological water quality, samples were taken from drinking water dispensers placed at S company (S-C) and U highschool (U-H) in Ulsan. The medians of heterotrophic plate counts (HPCs) were 53 CFU/ml for the 74 water samples of S-C and 80 CFU/ml for the 36 cold water samples of U-H, and 38% of the S-C and 42% of the U-H samples showed HPC bacterial concentrations higher than 100 CFU/ml. Coliform bacteria were detected from one sample of S-C. To determine the major source of bacterial contamination, water samples were taken daily for $6\sim8$ days from the bottled water containers as well as the faucets of an experimental water dispenser. While the average HPCs in the bottled water containers were 33 CFU/ml for the first and 132 CFU/ml for the 2nd analysis, the HPC concentration in the cold water samples was 1,022 CFU/ml for the 2nd analysis. These results suggest that the majority of bacteria detected in the cold water samples were originated from the biofilms on the surface of water passages within the water dispensers. There was no significant increase in HPC bacterial concentrations within the bottled water container after installation on the water dispenser. We could isolate and tentatively identify 3 genera 6 species of Gram-positive and 7 genera 7 species of Gram-negative bacteria from the plate count agar plates of U-H samples. Among the isolates, 72% were observed as Gram-positive, and Micrococcus spp. was the most abundant with 54% of the total, followed by Sphingomonas paucimobilis with 16%. It appears that most of the HPC bacteria detected in water dispensers originate from indoor airborne bacteria, which may play important roles in the formation of biofilms on the surface of water passages within the water dispensers.