• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.952-964
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• 2005

The diesel-degrading activities of biofilms sampled from petroleum-contaminated groundwaters in urban subway drainage systems were examined in liquid cultures, and the microbial populations of the biofilms were characterized by denaturing gel gradient electrophoresis (DGGE) and 16S rDNA sequence analysis. Biofilm samples derived from two sites (19 K and 20 K) at subway Station N and Station I could degrade around $80\%$ of applied diesel within 20 and 40 days, respectively, at $15^{\circ}C$, and these results were strongly correlated with the growth patterns of the biofilms. The closest phylogenetic neighbor of a dominant component in the 19 K biofilm was Thiothrix fructosivorans strain Q ($100\%$ similarity). Four dominant strains in the 20 K biofilm were closely related to Thiothrix fructosivorans strain Q ($100\%$ similarity), Thiothrix sp. CC-5 ($100\%$ similarity), Sphaerotilus sp. IF14 ($99\%$ similarity), and Cytophaga-Flexibacter-Bacterioides (CFB) group bacterium RW262 ($98\%$ similarity). Three dominant members in the Station I biofilms were very similar to uncultured Cytophagales clone CRE-PA82 ($91\%$ similarity), Pseudomonas sp. WDL5 ($97\%$ similarity), and uncultured CFB group bacterium LCK-64 ($94\%$ similarity). The microbial components of the biofilms differed depending on the sampling site. This is the first report on the isolation of clones highly similar to Thiothrix fructosivorans and Thiothrix sp. from biofilms in petroleum-polluted groundwaters, and the first evidence that these organisms may play major roles in petroleum degradation and/or biofilm-development.

• International Journal of Oral Biology
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• v.46 no.1
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• pp.60-65
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• 2021

Dental health care workers (DHCW) are at a risk of occupational exposure to Helicobacter pylori from the aerosolized oral biofilms and saliva of patients. We designed this study to investigate the prevalence of H. pylori in the oral biofilms of a group of dental and non-dental undergraduates from Sri Lanka. After obtaining informed consent, oral biofilms were collected from 38 dental undergraduates (19 males and 19 females) undergoing clinical training and 33 non-dental undergraduates (14 males and 19 females). The participants were in the age range of 22-27 years and had healthy periodontium. Total DNA from the oral biofilms were extracted, and H. pylori DNA was detected using polymerase chain reaction (PCR) amplification of 16S rRNA gene of H. pylori using JW22-JW23 primers, and the results were confirmed using PCR amplification of H. pylori-urease specific HPU1-HPU2 primers. Out of 71 participants, 11 (28.95%) dental and 3 (9.09%) non-dental undergraduates had H. pylori in their oral biofilms indicating an overall prevalence rate of 19.72% (14/71). Thus, the prevalence of H. pylori in oral biofilms was significantly higher in dental undergraduates than in non-dental undergraduates (p < 0.05). An odds ratio of 4.07 indicated that dental undergraduates were four times more likely to harbor H. pylori in their oral biofilms than non-dental undergraduates. Foregoing data support the fact that there may be greater occupational risk of exposure to H. pylori for dental undergraduates during clinical training than that for non-dental undergraduates, warranting meticulous infection control practices during clinical dentistry.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.6-10
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• 1998

A plasmid vector containing two reporter genes, mer-lux and lac-GFP, was transformed to both Escherichia coli and Pseudomonas putida. Their cellular activities and biofilm characteristics were investigated in flow-cell units by measuring bioluminescent lights and fluorescent levels of GFP. Bioluminescence was effective to monitor temporal cell activities, whereas fluorescent level of GFP was useful to indicate the overall cell activities during biofilm development. The light production rates of E. coli and P. putida cultures were dependent upon concentrations of HgCl2. Mercury molecules entrapped in P. putida biofilms were hardly washed out in comparison with those in E. coli biofilms, indicating that P. putida biofilms may have higher affinity to mercury molecules than E. coli biofilms. It was observed that P. putida expressed GFP cDNA in biofilms but not in liquid cultures. This may indicate that the genetic mechanisms of P. putida were favorably altered in biofilm conditions to make a foreign gene expression possible.

• The korean journal of orthodontics
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• v.53 no.6
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• pp.345-357
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• 2023

Enamel demineralization represents the most prevalent complication arising from fixed orthodontic treatment. Its main etiology is the development of cariogenic biofilms formed around orthodontic appliances. Ordinarily, oral biofilms exist in a dynamic equilibrium with the host's defense mechanisms. However, the equilibrium can be disrupted by environmental changes, such as the introduction of a fixed orthodontic appliance, resulting in a shift in the biofilm's microbial composition from non-pathogenic to pathogenic. This alteration leads to an increased prevalence of cariogenic bacteria, notably mutans streptococci, within the biofilm. This article examines the relationships between oral biofilms and orthodontic appliances, with a particular focus on strategies for effectively managing oral biofilms to mitigate enamel demineralization around orthodontic appliances.

• The Plant Pathology Journal
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• v.38 no.4
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• pp.334-344
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• 2022

Bacterial wilt is a re-emerging disease on dry bean and can affect many other crop species within the Fabaceae. The causal agent, Curtobacterium flaccumfaciens pv. flaccumfaciens (CFF), is a small, Gram-positive, rod-shaped bacterium that is seed-transmitted. Infections in the host become systemic, leading to wilting and economic loss. Clean seed programs and bactericidal seed treatments are two critical management tools. This study characterizes the efficacies of five bactericidal chemicals against CFF. It was hypothesized that this bacterium was capable of forming biofilms, and that the cells within biofilms would be more tolerant to bactericidal treatments. The minimum biocide eradication concentration assay protocol was used to grow CFF biofilms, expose the biofilms to bactericides, and enumerate survivors compared to a non-treated control (water). Streptomycin and oxysilver bisulfate had EC95 values at the lowest concentrations and are likely the best candidates for seed treatment products for controlling seed-borne bacterial wilt of bean. The results showed that CFF formed biofilms during at least two phases of the bacterial wilt disease cycle, and the biofilms were much more difficult to eradicate than their planktonic counterparts. Overall, biofilm formation by CFF is an important part of the bacterial wilt disease cycle in dry edible bean and antibiofilm bactericides such as streptomycin and oxysilver bisulfate may be best suited for use in disease management.

• Journal of Korean society of Dental Hygiene
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• v.23 no.4
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• pp.209-218
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• 2023

Objectives: To confirm the antibacterial effects of each mouth rinse on multiple oral biofilms in vitro. Methods: The antibacterial effects of different mouth rinses were examined by ATP and counted colony forming units (CFU). Preformed oral biofilms on saliva coated hydroxyapatite (sHA) disks were treated with essential oil and saline; then, the multiple oral biofilms were observed by Scanning electron microscope (SEM). RNA sequencing analysis was performed on total RNA isolated from old biofilms of P. intermedia ATCC 49046. Results: In the CFU measured result compared to controls, preformed multiple oral biofilms were reduced from a low of 39.0% to 95.7% (p<0.05). The size of bacterial cells changed after treatment with the essential oil, and some of the cells ruptured into small pieces of cell debris. Gene expression in P. intermedia ATCC 49046 significantly altered in RNA transcribed and protein translated genes after exposure to essential oil. Conclusions: Mouth rinse solutions with different ingredients had different antibacterial effects and may alter surface structure and gene expression as determined by RNA sequencing.

• Journal of Periodontal and Implant Science
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• v.47 no.4
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• pp.219-230
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• 2017

Purpose: The purpose of this study was to compare the characteristics of single- and dualspecies in vitro oral biofilms made by static and dynamic methods. Methods: Hydroxyapatite (HA) disks, 12.7 mm in diameter and 3 mm thick, were coated with processed saliva for 4 hours. The disks were divided into a static method group and a dynamic method group. The disks treated with a static method were cultured in 12-well plates, and the disks in the dynamic method group were cultured in a Center for Disease Control and Prevention (CDC) biofilm reactor for 72 hours. In the single- and dual-species biofilms, Fusobacterium nucleatum and Porphyromonas gingivalis were used, and the amount of adhering bacteria, proportions of species, and bacterial reduction of chlorhexidine were examined. Bacterial adhesion was examined with scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Results: Compared with the biofilms made using the static method, the biofilms made using the dynamic method had significantly lower amounts of adhering and looser bacterial accumulation in SEM and CLSM images. The proportion of P. gingivalis was higher in the dynamic method group than in the static method group; however, the difference was not statistically significant. Furthermore, the biofilm thickness and bacterial reduction by chlorhexidine showed no significant differences between the 2 methods. Conclusions: When used to reproduce periodontal biofilms composed of F. nucleatum and P. gingivalis, the dynamic method (CDC biofilm reactor) formed looser biofilms containing fewer bacteria than the well plate. However, this difference did not influence the thickness of the biofilms or the activity of chlorhexidine. Therefore, both methods are useful for mimicking periodontitis-associated oral biofilms.

• Journal of Microbiology
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• v.41 no.3
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• pp.183-188
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• 2003

We isolated and cultured bacteria that inhabited marine biofilms, and identified them by phylogenetic analysis using 16S rDNA sequences. In the marine environment, biofilms cover most subtidal and intertidal solid surfaces such as rocks, ships, loops, marine animals, and algae. The bacteria in most biofilms are embedded in extracellular polymeric substances that comprise mainly of exopolysaccharides. The exopolysaccharides are excreted from multiple bacterial species; therefore, biofilms are a good source for screening exopolysaccharide-producing bacteria. Thirty-one strains were cultured, and a total of 17 unique strains were identified. Phylogenetic analysis using 16S rDNA sequences indicated that the 17 strains belonged to ${\alpha}$-Proteobacteria (Ochrobactrum anthropi, Paracoccus carotinifaciens); ${\gamma}$-Proteobacteria (Pseudoalteromonas agarovorans, P. piscicida, Pseudomonas aeruginosa, Shewanella baltica, Vibrio parahaemolyticus, V. pomeroyi); CFB group bacteria (Cytophaga latercula, Tenacibaculum mesophilum); high GC, Gram-positive bacteria (Arthrobacter nicotianae, Brevibacterium casei, B. epidermidis, Tsukamurella inchonensis); and low GC, Gram-positive bacteria (Bacillus macroides, Staphylococcus haemolyticus, S. warneri).

• Food Science and Biotechnology
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• v.18 no.2
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• pp.556-560
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• 2009

Xanthorrhizol, a sesquiterpene isolated from Curcuma xanthorrhiza Roxb., was used to investigate its effect on reducing the saliva and multi-species oral biofilms consisting of Streptococcus mutans, Streptococcus sanguis, and Actinomyces viscosus by anti-biofilm and confocal laser scanning microscopy (CLSM) assays. Xanthorrhizol exhibited significant antibiofilm activity in the dose- and time-dependent manners. Exposure to 2 and $5{\mu}g/mL$ xanthorrhizol for 30 min remained <50% of saliva and multi-species biofilms formed for 24 hr. In addition, exposure to $10{\mu}g/mL$ xanthorrhizol for 30 min reduced 65 and 77% of 24 hr saliva and multi-species oral biofilms, respectively. CLSM results visually demonstrated that xanthorrhizol reduced bacterial viability in the saliva and multi-species oral biofilms. These results suggest that C. xanthorrhiza Roxb. containing xanthorrhizol with strong anti-biofilm activity can be employed as a plant source for oral care functional foods.