• 대한치과의사협회지
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• 제53권5호
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• pp.318-325
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• 2015

Peri-implantitis is defined as an inflammatory process affecting the tissues around an osseointegrated implant, resulting in the loss of the supporting bone. Microbial adherence and colonization appear to play a major role in the pathogenesis of periimplantitis. The decision regarding treatment strategies is based on the diagnosis. The severity of the peri-implant lesion and the treatment strategies must include mechanical cleaning (infection control) procedures. Mechanical instrumentation is widely used for the debridement of dental implants, but this may alter the titanium's surface properties. Therefore, selection of the type of instrumentation should be made depending on the type of surface to be debrided. Also, patients with dental implants must always be enrolled in a supportive therapy program.

• 대한치과의사협회지
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• 제48권2호
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• pp.113-118
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• 2010

Titanium and titanium alloys are the most common materials used for dental and biomedical implants, owing to their biocompatibility and favourable mechanical properties. However infection of the region surrounding a dental implant by pathogenic microorganisms is a significant factor in implant failure. Prevention and control of microbial colonization of implant surfaces is considerable interest to the biomedical community. One important strategy is to render the implant surface antibacterial by impeding the formation of biofilm. A number of approaches have been proposed for this purpose. Therefore, we reviewed the researches of antibacterial coatings on titanium implants in this articles.

• Clinical and Experimental Pediatrics
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• 제60권10호
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• pp.307-311
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• 2017

Necrotizing enterocolitis (NEC) is a devastating condition of hospitalized preterm infants. Numerous studies have attempted to identify the cause of NEC by examining the immunological features associated with pathogenic microorganisms. No single organism has proven responsible for the disease; however, immunological studies are now focused on the microbiome. Recent research has investigated the numerous bacterial species residing in the body and their role in diseases in preterm infants. The timing of initial microbial colonization is a subject of interest. The microbiome appears to transfer from the mother to the newborn, as well as to the fetus. Cross-talk between the fetus and fetal microbiome takes place continuously to generate a unique immune system. This review examined the transfer of the microbiome to the human fetus, and its potential relationship with NEC.

• Molecules and Cells
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• 제42권4호
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• pp.313-320
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• 2019

Intraepithelial lymphocytes (IELs) develop through the continuous interaction with intestinal antigens such as commensal microbiome and diet. However, their respective roles and mutual interactions in the development of IELs are largely unknown. Here, we showed that dietary antigens regulate the development of the majority of $CD8{\alpha}{\beta}$ IELs in the small intestine and the absence of commensal microbiota particularly during the weaning period, delay the development of IELs. When we tested specific dietary components, such as wheat or combined corn, soybean and yeast, they were dependent on commensal bacteria for the timely development of diet-induced $CD8{\alpha}{\beta}$ IELs. In addition, supplementation of intestinal antigens later in life was inefficient for the full induction of $CD8{\alpha}{\beta}$ IELs. Overall, our findings suggest that early exposure to commensal bacteria is important for the proper development of dietary antigen-dependent immune repertoire in the gut.

• 대한치과교정학회지
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• 제54권4호
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• pp.199-209
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• 2024

The clinical application of aligners is accompanied by the ageing of the polymer appliances and the attachments used, which may result in inefficiency in reaching the predicted range of tooth movement, and release of compounds and microplastics in the oral cavity as a result of the friction, wear and attrition of the aligner and composite attachment. The purpose of this review is to present the mechanism and effects of in vivo ageing; describe the hydrolytic degradation of aligners and enzymatic degradation of composite attachments; examine the ageing pattern of aligners in vivo, under actual clinical scenarios; and identify a link to the discrepancy between predicted and actual clinical outcome. Lastly, strategies to deal with three potentially critical issues associated with the use of aligners, namely the necessity of weekly renewal, the dissimilar mechanical properties of aligner and attachment resulting in wear and plastic deformation of the aligner, and the development of integuments and biofilms with microbial colonization of the appliance, are discussed.

• 한국환경농학회지
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• 제27권2호
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• pp.133-138
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• 2008

Fire can affect microbial community structure of soil through altered environmental conditions, nutrient availability, and biotic source for microbial re-colonization. We examined the influence of fire on chemical properties and soil enzyme activities of soil for 10 months. We also characterized the soil microbial community structure through ester-linked fatty acid analysis(EL-FAME). For this study, we established five burned plots(1*1 m) and 5 unburned plots outside the margin of fire. Soil was sampled three soil cores in a each plots and composited for analysis at 1, 3, 5, 8, and 10 month after fire. The fire caused an increase in soil pH, exchangeable Ca, and Mg, organic matter, available $P_2O_5$ compared to unburned sites. The content of $NH_4-N$ in burned site was significantly higher than that of unburned site and this effect continued for 8 months after fire. There was no difference of $NO_3-N$ content in soil between burned and unburned site. Fire caused no change in acid phosphatase and arylsulfatase activities but $\beta$-glucosidase and alkaline phosphatase activities in burned site were increased compared to unburned site. Microbial biomass as estimated by total concentration of EL-FAMEs in burned sites was significantly higher than that of unburned sites at one month after fire. Burned site decreased the EL-FAMEs indicative of gram-positive bacteria and tended to increase the fatty acid associated with gram-negative bacteria at one and three months after fire. The sum of EL-FAME compound $18:2{\omega}6,9c$ and $18:1{\omega}9c$ as served fungal biomarkers was decreased in burned site compared to unburned site.

• Asian-Australasian Journal of Animal Sciences
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• 제25권1호
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• pp.66-74
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• 2012

The effects of exogenous fibrolytic enzymes (EFE; a mixture of two preparations from Trichoderma spp., with predominant xylanase and ${\beta}$-glucanase activities, respectively) on colonization and digestion of ground barley straw and alfalfa hay by Fibrobacter succinogenes S85 and Ruminococcus flavefaciens FD1 were studied in vitro. The two levels (28 and 280 ${\mu}g$/ml) of EFE tested and both bacteria were effective at digesting NDF of hay and straw. With both substrates, more NDF hydrolysis (p<0.01) was achieved with EFE alone at 280 than at 28 ${\mu}g$/ml. A synergistic effect (p<0.01) of F. succinogenes S85 and EFE on straw digestion was observed at 28 but not 280 ${\mu}g$/ml of EFE. Strain R. flavefaciens FD1 digested more (p<0.01) hay and straw with higher EFE than with lower or no EFE, but the effect was additive rather than synergistic. Included in the incubation medium, EFE showed potential to improve fibre digestion by cellulolytic ruminal bacteria. In a second batch culture experiment using mixed rumen microbes, DM disappearance (DMD), gas production and incorporation of $^{15}N$ into particle-associated microbial N ($^{15}N$-PAMN) were higher (p<0.001) with ammoniated (5% w/w; AS) than with native (S) ground barley straw. Application of EFE to the straws increased (p<0.001) DMD and gas production at 4 and 12 h, but not at 48 h of the incubation. EFE applied onto S increased (p<0.01) $^{15}N$-PAMN at 4 h only, but EFE on AS increased (p<0.001) $^{15}N$-PAMN at all time points. Prehydrolysis increased (p<0.01) DMD from both S and AS at 4 and 12 h, but reduced (p<0.01) $^{15}N$-PAMN in the early stage (4 h) of the incubation, as compared to non-prehydrolyzed samples. Application of EFE to barley straw increased rumen bacterial colonization of the substrate, but excessive hydrolytic action of EFE prior to incubation decreased it.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1286-1298
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• 2005

The genus Paenibacillus is a new group of bacilli separated from the genus Bacillus, and most of species have been isolated from soil. In the present study, we collected 450 spore-forming bacilli from the roots of winter crops, such as barley, wheat, onion, green onion, and Chinese cabbage, which were cultivated in the southern part of Korea. Among these 450 isolates, 104 Paenibacillus-like isolates were selected, based on their colony shape, odor, color, and endospore morphology, and 41 isolates were then finally identified as Paenibacillus spp. by 16S rDNA sequencing. Among the 41 Paenibacillus isolates, 23 were classified as P. polymyxa, a type species of the genus Paenibacillus, based on comparison of the 16S rDNA sequences with those of 32 type strains of the genus Paenibacillus from the GenBank database. Thirty-five isolates among the 41 Paenibacillus isolates exhibited antagonistic activity towards plant fungal and bacterial pathogens, whereas 24 isolates had a significant growth-enhancing effect on cucumber seedlings, when applied to the seeds. An assessment of the root-colonization capacity under gnotobiotic conditions revealed that all 41 isolates were able to colonize cucumber roots without any significant difference. Twenty-one of the Paenibacillus isolates were shown to contain the nifH gene, which is an indicator of $N_{2}$ fixation. However, the other 20 isolates, including the reference strain E681, did not incorporate the nifH gene. To investigate the diversity of the isolates, a BOX-PCR was performed, and the resulting electrophoresis patterns allowed the 41 Paenibacillus isolates to be divided into three groups (Groups A, B, and C). One group included Paenibacillus strains isolated mainly from barley or wheat, whereas the other two groups contained strains isolated from diverse plant samples. Accordingly, the present results showed that the Paenibacillus isolates collected from the rhizosphere of winter crops were diverse in their biological and genetic characteristics, and they are good candidates for further application studies.

• 한국토양비료학회지
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• 제50권3호
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• pp.135-149
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• 2017

In order to obtain promising rice growth-promoting microbial strains that can be used as substitutes for chemical fertilizers, 172 bacterial strains were isolated from rice roots grown in Korean and Russian soils. Out of them, the strains KR076, KR083, KR181 and RRj228 showed plant growth-promoting activities on maize seedlings. Bacillus megaterium KR076 and Bacillus sp. KR083 showed both nitrogen-fixing and plant growth-promoting activities, while Rhizobium sp. KR181 and Pseudomonas sp. RRj228 appeared to support only plant growth-promotion, but not $N_2$ fixation. Especially, RRj228 showed high growth promoting activity at low concentrations. Inoculation studies with KR083 and RRj228 revealed a high affinity to the Japonica rice variety such as Junambyeo than the Korean Tongil type variety such as Arumbyeo. Both KR083 and RRj228 strains showed rhizoplane and/or endophytic colonization in Japonica and Tongil types rice when soaked with the bacterial suspension of $1.1{\times}10^5cfu\;ml^{-1}$ for six and twelve hours. However, the total bacterial cell numbers were higher in the roots of Japonica variety than in the Tongil type. In inoculation trials with Daesanbyeo rice variety, the seedlings inoculated with KR181 and RRj228 at the rate of $2.0{\times}10^6cfu\;ml^{-1}$ showed yield increment of 35% and 33% (p < 0.01), respectively, so that they contributed to the replacement of chemical fertilizer at half doses of N, $P_2O_5$, and $K_2O$ in pots. In Junambyeo rice seedlings, the strain RRj228, when inoculated with a cell suspension of $1.8{\times}10^6cfu\;ml^{-1}$, promoted 3.4% higher yield at 70% dose than at a full dose level of N $110kg\;ha^{-1}$ in field. These results suggest that the rhizobacteria KR181 and RRj228 are prospective strains for enhancing rice performance.

• The Plant Pathology Journal
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• 제25권1호
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• pp.62-69
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• 2009

In this study, we characterized the bacterial strain KJ2C12 in relation with its biocontrol activity against Phytophthora capsici on pepper, and identified this strain using morphological, physiological, biochemical, fatty acid methyl ester, and 16S rRNA gene sequence analyses. Strain KJ2C12 significantly (P=0.05) reduced both final disease severity and areas under the disease progress curves of 5-week-old pepper plants inoculated with P. capsici compared to buffer-treated controls. As for the production of antibiotics, biofilms, biosurfactant, extracellular enzyme, HCN, and swarming activity, strain KJ2C12 produced an extracellular enzyme with protease activity, but no other productions or swarming activity. However, Escherichia coli produced weak biofilm only. Strain KJ2C12 could colonize pepper roots more effectively in a gnotobiotic system using sterile quartz sand compared to E. coli over 4 weeks after treatments. However, no bacterial populations were detected in 10 mM $MgSO_4$ buffer-treated controls. Strain KJ2C12 produced significantly higher microbial activity than the $MgSO_4$-treated control or E. coli over 4 weeks after treatments. Bacterial strain KJ2C12 was identified as Bacillus luciferensis based on morphological, physiological, and biochemical characteristics as well as FAME and 16S rRNA gene sequence analyses. In addition, these results suggested that B. luciferensis strain KJ2C12 could reduce Phytophthora blight of pepper by protecting infection courts through enhanced effective root colonization with protease production and an increase of soil microbial activity.