• Journal of Microbiology and Biotechnology
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• 제25권3호
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• pp.381-385
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• 2015

In the present study, drop-on-demand two-dimensional patterning of unstained and stained bacterial cells on untreated clean wafers was newly conducted using an electrospray pulsed jet. We produced various spotted patterns of the cells on a silicon wafer by varying the experimental conditions, such as the frequency, flow rate, and translational speed of the electrospray system in a two-dimensional manner. Specifically, the electrospray's pulsed jet of cell solutions produced alphabetical patterns consisting of spots with a diameter of approximately $10{\mu}m$, each of which contained a single or a small number of viable bacteria. We tested the viability of the patterned cells using two visualization methods. This pattering technique is newly tested here and it has the potential to be applied in a variety of cell biology experiments.

• 한국물환경학회지
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• 제20권5호
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• pp.506-511
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• 2004

Maintaining dissolved oxygen (DO) at sufficiently low concentration in the aeration tank at a wastewater treatment plant (WWTP) is essential for reduction of the costs of operation and maintenance. On the other hand, the low DO level may result in adverse effect on the integrity of the activated sludge, A typical and disastrous outcome frequently experienced is the outgrowth of filamentous microorganisms, which is called as filamentous bulking, In addition to the traditional methods such as sludge settleability and microscopic observation of the culture, molecular techniques including polymerase chain reaction (PCR) amplification followed by 16S rRNA sequencing were applied to identify filamentous bacteria present in bulking sludge under a condition of low DO concentration, Two morphologically distinct groups, presumably consisting of Sphaerofilus nafans, and Eikelboom Type 1701 or Type 1851, were identified through microscopic observation. They were further confirmed by subsequent 16S rRNA sequencing. Dominant filamentous bacteria identified by the molecular techniques were consisted of three major groups. Sequences of partial 16S rRNA cloned showed that the filamentous bulking organisms were closely related to Eikelboom Type 021N and Eikelboom Type 1701, and Sphaerotilus natans, respectively. Molecular methods were found to possess a strong potential of direct examination of the microbial community of an activated sludge system.

• 구강회복응용과학지
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• 제33권3호
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• pp.178-188
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• 2017

목적:본 연구에서는 새로 개발된 다이오드 레이저 제품을 이용하여 레이저 파워에 따른 온도변화와 박테리아 멸균 비교실험을 통하여 기존 제품과의 임플란트 주위염치료에 대한 효과를 비교 실험하였다. 연구 재료 및 방법: 808 nm Diode laser와 810 nm Diode laser를 사용하여 디스크에 레이저를 60초간 조사하였으며, 출력은 1 - 2.5 W로 설정하였다. 온도측정 모듈과 온도측정 프로그램을 이용하여 disc 표면온도변화를 측정하였다. 또한, SLA, RBM이 코팅된 disc에 bacteria 도포 후, 808 nm Diode laser를 30초간 조사하였으며, 출력은 0.5 - 3 W로 설정하였다. 결과: 808 nm, 810 nm 두 장치 모두 출력이 증가함에 따라 온도 상승폭은 증가하였다. 모든 조건에서 810 nm laser를 조사하였을 때 초기온도상승속도, 하강속도 및 전후의 온도변화량은 808 nm laser 보다 높았다. 레이저 조사 후 티타늄 디스크 표면의 변화는 두 레이저 모두에서 관찰되지 않았다. Bacteria가 도포된 디스크에 808 nm laser를 조사한 결과, 출력이 증가 함에 따라 살균효과가 증가하는 것을 확인하였다. 결론: Diode laser를 임상에 적용하는 경우, 동일한 출력에서 온도의 변동폭이 적고 최대 상승온도가 낮은 808 nm laser가 환자에 안전할 것으로 사료된다. 하지만 실제로 임상에 적용하기 위해서는 보다 다양한 안전성평가를 실시하여 장비에 대한 신뢰성을 확보하여야 할 것이다.

• Journal of Periodontal and Implant Science
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• 제39권3호
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• pp.303-310
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• 2009

Purpose: The aerosol generated by ultrasonic scaler can contain bacteria or virus which can penetrate into body through respiratory systems of dentists, dental hygienist or patients. The aim of this study is to evaluate the effect of chlorhexidine digluconate as preoperative mouthrinse or lavage for ultrasonic scaler on the reduction of viable organisms in aerosol produced during periodontal treatment using ultrasonic scaler. Methods: 30 patients with moderate chronic periodontitis were included and divided into 3 groups: Control (no preoperative mouthrinse and tap water as lavage), CHG (preoperative mouthrinse with 0.1% chlorhexidine digluconate and tap water as lavage), CHL (no preoperative mouthrinse and 0.1% chlorhexidine digluconate as lavage). Each patient received scaling or subgingival curettage for 30 min. In CHG group, mouthrinse with chlorhexidine digluconate was performed for 1 min. before treatment. Before, during and after scaling or subgingival curettage, air sampling was performed for 7 min. each (1000 L/7 min.) with trypticase-soy agar plate. Agar plates were incubated in $37^{\circ}C$ aerobically. The numbers of colony-forming units (CFU) were counted and compared. Results: The numbers of CFUs of the samples obtained during treatment were $97{\pm}14.0$ in control, $73.1{\pm}14.9$ in CHG group and $44.5{\pm}9.0$ in CHL group. The difference among the 3 groups was determined to be statistically significant (one-way ANOVA with Bonferroni's correction, p-value: 0.0003). In contrast, the numbers of CFU of samples obtained before and after treatment were not significantly different among the groups. Conclusions: Chlorhexidine digluconate used as preoperative mouthrinse or lavage for ultrasonic scaler can reduce the microorganisms in aerosol produced during periodontal treatment using ultrasonic scaler. Less number of microorganisms were detected when chlorhexidine was used as lavage for ultrasonic scaler.

• 한국식품조리과학회지
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• 제24권4호
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• pp.445-451
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• 2008

This study compared the effects of chlorine dioxide and a commercial chlorine sanitizer for inhibiting foodborne pathogens, including Salmonella enterica serovar Typhimurium, Listeria monocytogenes, and Escherichia coli O157 : H7, on lettuce leaves. The lettuce samples were inoculated with each cocktail of the three strains, and were then treated with chemical sanitizers [distilled water, 100 ppm commercial chlorine and 50 ppm, 100 ppm, 200 ppm chlorine dioxide ($ClO_2$)] for 1 min, 5 min, and 10 min at room temperature($22{\pm}2^{\circ}C$). Following inoculation of the leaves, initial populations of E. coli O157:H7, L. monocytogenes, and S. Typhimurium were approximately 5.54, 4.47, and 5.12 log CFU/g, respectively these levels were not significantly reduced by the treatment with water,whereas the 100 ppm commercial chlorine sanitizer treatment and $ClO_2$ (at all tested concentrations) were effective at reducing levels of all three pathogens. The treatment of 200 ppm $ClO_2$ for 10 min was most effective at inhibiting the three pathogens, and reduction levels of E. coli O157 : H7, L. monocytogenes, and S. Typhimurium were 2.28, 1.95, 1.76 log, respectively. The inhibitory effect of $ClO_2$ increased with increasing treatment concentration of $ClO_2$, but there was no significant difference by the treatment times. When chemically injured cells of E. coli O157 : H7 and L. monocytogenes and S. Typhimurium were examined by SPRAB and selective overlay methods, respectively, it was observed that the commercial chlorine sanitizer generated greater numbers of injured L. monocytogenes than the $ClO_2$ treatment. From the overall results, $ClO_2$ was more effective at inhibiting pathogenic bacteria compared to the commercial chlorine sanitizer therefore, it has potential to be utilized as an alternative sanitizer to increase the microbial safety of fresh produce.

• Asian-Australasian Journal of Animal Sciences
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• 제31권8호
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• pp.1308-1314
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• 2018

Objective: Gut health improvements were monitored with respect to growth performance, diarrhea incidence, fecal bacterial population and intestinal morphology of suckling pigs orally supplemented with live Lactobacillus salivarius (L. salivarius) oral suspensions and challenged with $F4^+$ enterotoxigenic Escherichia coli (ETEC). Methods: Two groups of newborn pigs from 18 multiparous sows were randomly designated as non-supplemented (control: n = 114 piglets) and L. salivarius supplemented groups (treatment: n = 87 piglets). Treatment pigs were orally administered with 2 mL of $10^9$ colony-forming unit (CFU)/mL L. salivarius on days 1 to 3, then they were orally administered with 5 mL of $10^9CFU/mL$ L. salivarius on days 4 to 10, while those in control group received an equal amount of phosphate buffered saline solution. On day 24 (2 weeks post supplementation), one pig per replicate of both groups was orally administered with $10^8CFU/mL$ $F4^+$ ETEC, then they were euthanized on day 29 of experiment. Results: Results revealed that pigs in treatment group had a statistically significant increase in average daily gain, body weight and weight gain, and tended to lower diarrhea throughout the study. Numbers of Lactobacillus population in feces of treatment pigs were higher than control pigs, especially on day 10 of study. Numbers of total bacteria in intestinal contents of control pigs were also increased, but not Coliform and Lactobacillus populations. Histological examination revealed statistically significant improvements of villous height and villous/crypt ratio of duodenum, proximal jejunum and distal jejunum parts of treatment pigs compared with controls. Duodenal pH of treatment group was significantly decreased. Conclusion: Oral supplementation of live L. salivarius during the first 10 days of suckling pig promoted growth performance and gut health, reduced diarrhea incidence, increased fecal Lactobacillus populations and improved intestinal morphology.

• 대한환경공학회지
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• 제35권1호
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• pp.57-63
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• 2013

고농도 질소를 함유한 하 폐수를 아질산염 축적 경로를 통하여 처리하고자 생물막공정과 연속혼합반응조의 탈질공정을 결합하여 운전하였다. 생물막 반응조의 폴리에틸렌 담체 표면에 아질산염 산화균에 비해서 암모늄 산화균의 성장을 촉진하여 아질산염을 선택적으로 축적하고자 반응조 온도를 $35^{\circ}C$로 유지하면서 석달 이상 장기간 운전하였음에도 불구하고 유입수 암모늄(500 mg-N/L)의 일부만 아질산염(240 mg-N/L)으로 전환되었다. 하지만 pH를 7.5에서 8.0으로 증가시켰을 때, 아질산염 산화균들이 높은 암모니아 농도에 성장 저해를 받아 생물막 공정에서 아질산염 축적을 성공적으로 이끌어낼 수 있었다. 생물막 공정의 수리학적 체류시간을 12시간으로 운전하였을 때, 반응조의 성능이 급격하게 저하되어 유입수의 암모늄이 완전히 산화되지 않았다. 하수슬러지의 생분해성을 높이기 위해서 다양한 가용화 기술을 적용한 결과, 알칼리와 초음파 처리를 순차적으로 병합하였을 때, 가장 높은 가용화율(58%)을 얻을 수 있었으며, 이를 탈질반응조의 외부탄소으로 사용하였다. FISH 분석결과로부터 담체표면에 암모늄 산화균인 Nitrosomonas와 Nitrospirar계열의 미생물들이 우점종이었으며 일부 아질산염 산화균인 Nitrobacter 계열의 미생물도 소량이지만 관찰되었다.

• 한국안광학회지
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• 제14권3호
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• pp.95-102
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• 2009

목적: 본 연구는 마늘 allyl 유도체의 안질환 세균에 대한 항균활성을 조사하고, 이를 다목적용액(MPS)에 응용함으로써 천연물유래 마늘성분을 이용하여 MPS 개발에 대한 기초자료를 얻고자 실시하였다. 방법: 녹농균(Pseudomonas aeruginosa)과 황색포도상구균(Staphyloccus aereus)에서 마늘유래 allyl 유도체인 diallyl sulfide(DAS)의 항균활성을 측정하였으며, 항균활성이 없는 MPS에 DAS를 함께 처리하여 세균의 생육억제 효과를 측정하였다. 결과: 50%의 생육저해($IC_{50}$)를 나타내는 DAS농도는 녹농균과 황색포도상구균 각각 0.25%와 0.64% 였다. MPS의 항균활성 실험에서 A사의 제품은 효과가 없었으며 B사의 제품은 두 균 모두에서 항균활성을 보였다. B사 MPS의 항균활성은 그람음성과 그람양성 세균에 대해 모두 유의한 차이를 나타내지 않았다. 따라서 DAS의 항균활성을 이용한 보존제의 개발을 위해 처리된 농도에서 항균활성을 나타내지 않은 A사의 MPS를 사용하여 A사의 MPS에 DAS를 첨가하여 항균활성을 조사한 바 DAS의 항균활성 효과가 나타났으며, 콘택트렌즈 살균제에 대한 적용가능성이 확인되었다. 결론: 마늘의 allyl 유도체는 황색포도상구균과 녹농균에 대한 항균작용을 나타내었으며, 녹농균에서 더큰 항균활성을 가지는 것으로 나타났다. 따라서 마늘성분과 같은 천연물유래 항균활성물질이 MPS의 보존제로 개발 가능성이 있음을 시사한다.

• 한국환경보건학회지
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• 제50권2호
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• pp.93-101
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• 2024

Background: As pollutants caused by non-point sources flow into rivers, river water quality monitoring for fecal pollution is becoming increasingly important. Objectives: This study was conducted to investigate the distribution of microbial communities in the Yeongsangang River water system and sewage treatment plants in Gwangju and to evaluate their antibiotic resistance. Methods: In the experiment, samples were distributed to five selective media at each point and then cultured for 18 to 24 hours. When bacteria were observed, they were sub-cultured by size and shape and identified using MALDI-TOF MS equipment. When identification was completed, 17 types of antibiotic susceptibility tests were performed using VITEK II equipment, focusing on gram-negative dominant species among the identified strains. Results: During the study period, a total of 266 strains were isolated from 39 samples. Gram-positive bacteria were 37 strains in four genera, or 13.9% of the total, and Gram-negative bacteria were 229 strains in 23 genera, or 86.1% of the total. Antibiotic susceptibility testing of 23 strains, the major dominant species, showed that one strain (4.3%) was resistant to only one antibiotic, and two strains (8.7%) were 100% susceptible to the 17 antibiotics tested. The other 20 strains (87.0%) were multidrug resistant bacteria resistant to two or more antibiotics. There were various types of multidrug resistance. Among them, penicillin and cephalosporin series showed the highest resistance. Conclusions: Based on the results of this study, it was found that the bacterial community structure changed according to regional and environmental factors, and it was judged that continuous research such as genetic analysis of antibiotic-resistant bacteria present in natural rivers is necessary.

• Journal of Periodontal and Implant Science
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• 제32권2호
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• pp.415-428
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• 2002

Periodontal disease is a complex infectious disease caused by bacteria in the oral mucosa, which results in gingival inflammation, breakdown of periodontal tissues, bone resorption, and finally tooth loss. Mechanical plaque control methods-scaling and root planing are effective methods to stop the progression of such periodontal disease. It was reported that subantimicrobial dose of doxycycline(SDD) regimen could improve clinical conditions of periodontal tissues without causing the overgrowth of opportunistic organisms that was a typical antibiotic side effect. Therefore pharmacological therapy, used in conjunction with mechanical therapy could be considered a useful treatment modality in the treatment of chronic periodontal disease. In this study, 30 patients diagnosed as moderate to advanced chronic periodontitis were divided into 2 groups. In this double-blind, placebo-controlled study, the patients were administered 20mg doxycycline capsule or placebo capsule b.i.d. for 4months, after scaling and root planing. Clinical parameters-bleeding on probing, pocket depth and clinical attachment level were compared and evaluated between these groups at periods of first visit, 1 month, 2 months, 3 months, 4 months. The results were as follows ; 1. In case of moderate periodontitis, pocket depth showed significant reduction after treatment in both the control & experiment groups, when compared with the baseline values(p<0.01), but in case of advanced periodontitis, only the experiment group showed significant reduction after treatment when compared with the baseline values(p<0.05). Statistically significant reduction in pocket depth was observed in the experiment group compared to the control group(p<0.05). 2. In case of moderate periodontitis, clinical attachment level showed significant reduction after treatment in both the control & experiment groups, when compared with the baseline values(p<0.01), but in case of advanced periodontitis, only the experiment group showed significant reduction after treatment when compared with the baseline values(p<0.05). Statistically significant reduction in clinical attachment level was observed in the experiment group compared to the control group(p<0.05). 3. Bleeding on probing improved after treatment in both the groups. In case of moderate periodontitis, the experiment group showed statistically significant reduction of bleeding on probing when compared with the control group at 1 and 4 months after treatment(p<0.05). In case of advanced periodontitis, treatment resulted in statistically significant reduction of bleeding on probing in both the groups(p<0.05). These results indicate that the use of subantimicrobial dose of doxycycline is a useful supplement to mechanical treatment for periodontal patients in ameliorating the clinical parameters such as periodontal pocket, attachment level, and bleeding on probing.