• 대한약침학회지
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• 제19권4호
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• pp.312-318
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• 2016

Objectives: Bacterial resistant infections have become a global health challenge and threaten the society's health. Thus, an urgent need exists to find ways to combat resistant pathogens. One promising approach to overcoming bacterial resistance is the use of herbal products. Green tea catechins, the major green tea polyphenols, show antimicrobial activity against resistant pathogens. The present study aimed to investigate the effect of catechins, green tea extract, and methylxanthines in combination with gentamicin against standard and clinical isolates of Staphylococcus aureus (S. aureus) and the standard strain of Pseudomonas aeruginosa (P. aeruginosa). Methods: The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values of different agents against bacterial strains were determined. The interactions of green tea extract, epigallate catechin, epigallocatechin gallate, two types of methylxanthine, caffeine, and theophylline with gentamicin were studied in vitro by using a checkerboard method and calculating the fraction inhibitory concentration index (FICI). Results: The MICs of gentamicin against bacterial strains were in the range of $0.312-320{\mu}g/mL$. The MIC values of both types of catechins were $62.5-250{\mu}g/mL$. Green tea extract showed insufficient antibacterial activity when used alone. Methylxanthines had no intrinsic inhibitory activity against any of the bacterial strains tested. When green tea extract and catechins were combined with gentamicin, the MIC values of gentamicin against the standard strains and a clinical isolate were reduced, and synergistic activities were observed (FICI < 1). A combination of caffeine with gentamicin did not alter the MIC values of gentamicin. Conclusion: The results of the present study revealed that green tea extract and catechins potentiated the antimicrobial action of gentamicin against some clinical isolates of S. aureus and standard P. aeruginosa strains. Therefore, combinations of gentamicin with these natural compounds might be a promising approach to combat microbial resistance.

• The Plant Pathology Journal
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• 제24권1호
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• pp.52-57
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• 2008

Twenty isolates of Bacillus spp. obtained from livestock manure composts and cotton-waste composts were tested for in vitro antagonistic effects against soilborne plant pathogenic fungi, Fusarium oxysporum, Phytophthora capsici, Rhizoctonia solani AG-4, and Sclerotinia sclerotiorum. Seven isolates of Bacillus spp. had antagonistic effects on mycelial growth of all the isolates of F. oxysporum tested. The bacterial isolate RM43 was the most effective to inhibit the mycelial growth of the fungal isolates. Twelve isolates of Bacillus spp. had antagonistic effects on mycelial growth of all the isolates of P. capsici tested. The bacterial isolates M34 and M47 were very effective to inhibit the mycelial growth of the fungal isolates. Thirteen isolates of Bacillus spp. had antagonistic effects on mycelial growth of all the isolates of R. solani AG-4 tested. The bacterial isolates M27 and M75 were very effective to inhibit the mycelial growth of the fungal isolates. Fourteen isolates of Bacillus sp. had antagonistic effects on mycelial growth of all the isolates of S. sclerotiorum tested. The bacterial isolates M49 and M75 were very effective to inhibit the mycelial growth of the fungal isolates. The antagonistic effects of most Bacillus spp. isolates against the isolates of the four fungi differed depending on the fungal species and the isolates of each fungus. The bacterial isolates M27 and M75 were the most effective to inhibit the mycelial growth of all four fungi.

• The Plant Pathology Journal
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• 제28권1호
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• pp.68-74
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• 2012

Biocontrol microbes have mainly been screened among large collections of microorganisms $via.$ nutrient-rich $in$ $vitro$ assays to identify novel and effective isolates. However, thus far, isolates from only a few genera, mainly spore-forming bacilli, have been commercially developed. In order to isolate field-effective biocontrol microbes, we screened for more than 200 oligotrophic bacterial strains, isolated from rhizospheres of various soil samples in Korea, which induced systemic resistance against the soft-rot disease caused by $Pectobacterium$ $carotovorum$ SCC1; we subsequently conducted in $planta$ bioassay screening. Two oligotrophic bacterial strains were selected for induced systemic disease resistance against the $Tobacco$ $Mosaic$ $Virus$ and the gray mold disease caused by $Botrytis$ $cinerea$. The oligotrophic bacterial strains were identified as $Pseudomonas$ $manteilii$ B001 and $Bacillus$ $cereus$ C003 by biochemical analysis and the phylogenetic analysis of the 16S rRNA sequence. These bacterial strains did not exhibit any antifungal activities against plant pathogenic fungi but evidenced several other beneficial biocontrol traits, including phosphate solubilization and gelatin utilization. Collectively, our results indicate that the isolated oligotrophic bacterial strains possessing induced systemic disease resistance could provide useful tools as effective biopesticides and might be successfully used as cost-effective and preventive biocontrol agents in the field.

• 한국동물위생학회지
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• 제45권3호
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• pp.191-199
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• 2022

We investigated the virulence genes, O-serotypes, antimicrobial resistance of pathogenic E. coli isolated from carcasses (n=455) and environmental (n=372) samples of 11 cattle and 12 pig slaughterhouses from December 2020 to December 2021. E. coli were isolated from nine carcasses (2.0%), three slaughter facilities (1.4%), two utensils (2.7%) and three abattoir workers (3.5%) from four cattle and four pig slaughterhouses. Among all isolates, 13 STEC (76.5%) were identified, followed by four EPEC (23.5%). As a result of the antibiotic susceptibility test, all isolates were resistant to at least one antimicrobial, of which 70.6% isolates showed multidrug resistance patterns. The serotypes were diverse in pigs compared to cattle, with serotypes O18, O66, O109 in cattle and O9, O76, O85, O100, O153, and O159 in pigs. In a single cattle slaughterhouse, eight STEC O66 were isolated from various types of sample (4 slaughter animal surfaces, 3 gloves, and 1 knife) with two antimicrobial resistance patterns (CHL-FIS-STR and CHL-FIS). Those two types of strain were suspected cross-contamination from utensils to slaughter animal surfaces. These results showed that pathogenic E. coli were detected in carcasses and various environmental samples in cattle and pig slaughterhouses. Nationwide monitoring and hygiene management are required to prevent cross-contamination of STEC isolate slaughterhouses.

• 한국동물위생학회지
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• 제45권3호
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• pp.181-189
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• 2022

Streptococcus is one of the major pathogen groups inducing bovine mastitis. The aim of this study was to investigate the antimicrobial resistance patterns of Streptococcus species isolated from bovine mastitis milk samples in Korea from 2016 to 2021. In total, 181 (10.3%) Streptococcal isolates were collected from 1,761 quarter milk samples at 122 farms; S. uberis 39.2% (n=71), S. dysgalactiae 29.3% (n=53), S. equinus 9.9% (n=18), S. suis 6.1% (n=11), S. parauberis 4.4% (n=8), S. lutetiensis 3.9% (n=7), others 7.2% (n=13). However, S. agalactiae was not isolated. The isolates showed the highest resistance rate to tetracycline (55.2%) followed by erythromycin (45.3%) and pirlimycin (36.5%). In contrast, all isolates were susceptible to ceftiofur, cephalothin, penicillin/novobiocin, and only single S. equinus isolate was resistant to both ampicillin and penicillin. Of 181 isolates, 64 (35.4%) were multidrug resistance (MDR). The resistance to pirlimycin of S. uberis (73.2%) was much higher than that of other species (0~36.4%). All S. suis isolates were resistance to tetracycline. S. dysgalactiae showed lower resistance to erythromycin, pirlimycin and tetracycline than S. uberis and S. suis. The rate of MDR was relatively higher among S. uberis (73.2%) than among S. suis (36.4%), S. dysgalactiae (15.1%), others (0%). In conclusion, antimicrobial resistance in Streptococcus spp. should be regularly examined for appropriate therapies because the resistance patterns were various among the individual species.

• Archives of Pharmacal Research
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• 제28권6호
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• pp.660-666
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• 2005

The intestinal microbiota are important to the host with regard to resistance they impart against bacterial infections and their involvement in mediating metabolic functions. Lactic acid producing bacteria such as Lactobacillus play an important physiological role in these matters. The aim of the present study was to isolate Lactobacillus sp. that inhibits enteric pathogens. Initially, 17 isolates from healthy Koreans were collected on Lactobacillus selective medium. Resistance of the isolates to antibiotics including rifampicin, streptomycin, clindamycin and vancomycin was measured. One of the isolate was identified as Lactobacillus ruminus on the basis of bacterial cell morphology, cultural characteristic and biochemical characteristics, 16S rRNA sequence analysis and PCR-RAPD. Antimicrobial activity of the bacterium against Vancomycin Intermediate Resistant Staphylococcus aureus (VISA) and Vancomycin-Resistant Enterococci (VRE) was measured. About $10^4$ cells of VISA or VRE were mixed with 1, 5, and 9 mL of L. ruminus SPM 0211 and the final volume was adjusted to 10 mL with brain heart infusion (BHI) broth. The cell suspension was incubated for 3, 6, 9, and 24 h, serially diluted and then plated on BHI agar plates. As numbers of L. ruminus SPM 0211 were increased, viable cell count of VISA and VRE decreased. The strongest antimicrobial activity of SPM 0211 was observed after 9 h incubation in any mixture, almost completely inhibiting the growth of these two bacteria. The results suggest that the freshly isolated L. ruminus SPM 0211 may be used as a pro-biotic microbe that prevents the colonization of enteric pathogens and can thereby promote good gastrointestinal health.

• 한국응용곤충학회지
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• 제10권2호
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• pp.97-101
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• 1971

벼 흰빛잎마름병의 병원균의 생리적 성질을 구명하고자 시험한 곁과는 다음과 같았다. 1, 공시균주로는 본 병리 연구 담당관실 보존균주 및 일본, 비율빈에서 분양받은 균주와 최근 IR 계통품종과 이병성 품종에서 채집 분리된 10균주를 공시하였다. 2. 탄소원의 분해 및 산도변화에서는 Glucose, Galactose는 모든 균주가 이용하였고 Esculin, Mannitol, Raffinose Salicin, Saccharose는 몇몇균주가 이용했으며 lactose, Starch, Dextrin은 이용하지 못하였다. 3. 시험에 사용된 공시균주는 유화수소 및 암모니아를 생성하였으며 methylene blue 환원시험에서는 환인이 일어났으며 인돌생성은 하지 않았고 젤라틴은 서서히 액화시켰지만 균중간에는 액화정토가 서로 차이가 났으며 우유의 소화 및 응결은 없었으며 리트머스 우유를 청변시켰다.

• KSBB Journal
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• 제31권3호
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• pp.158-164
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• 2016

Plant growth promoting (PGP) hormones, which are produced in a small quantity by bacteria, affect in plant growth and development. PGPs play an important role on the crop productivity in agricultural field. In this study, a photosynthetic bacterial strain producing the PGP was isolated from paddy soil. Bacterial isolate was gram negative, rod-shaped and motility positive. From the 16s rRNA gene sequence analysis, the isolate was identified as Rhodobacter capsulatus PS-2. The mass cultivation of R. capsulatus PS-2 was optimized by considering of the carbon, nitrogen and inorganic salt sources. Optimal medium composition was determined as Na-succinate 4.5 g, yeast extract 5 g, $K_2HPO_4$ 1 g, $MgSO_4$ 5 g, per liter. From the result of 500 L fermentation for 2 days using the optimal medium, the viable cells were $8.7{\times}10^9cfu/mL$. R. capsulatus PS-2 strain produced the carotenoid and indole-3-acetic acid (IAA). The carotenoid extraction and quantitative analysis were performed by HCl-assisting method. Total carotenoid contents from R. capsulatus PS-2 culture broth were measured as $7.02{\pm}0.04$ and $6.93{\pm}0.05mg/L$ under photoheterotrophic and chemoheterotrophic conditions, respectively. To measure the productivity of IAA, colorimetric method was employed using Salkowski reagent at optical density 535 nm. The results showed that the highest content of IAA was $197.44{\pm}5.92mg/L$ in the optimal medium supplemented with 0.3% tryptophan.

• 미생물학회지
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• 제38권2호
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• pp.107-112
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• 2002

남조류 분해세균을 분리하기 위하여 도창, 팔당 저수지와 석촌 호수로부터 저층시료를 채취하였다. Anabaena cylindrica lawn에 각각의 시료를 도말한 후 11 일간 배양하였고 석촌 시료를 접중한 Anabaena cylindrica lawn에서 Anabaena cylindrica에 분해능을 가지는 세균을 분리하였다. 분해능 화인은 남조류와 분해세균을 혼합한 후 chlorophyll a간의 측정과 분리세균의 cell counting방법으로 확인하였고, 세포외 물질이 Anabaena cylindrica를 분해하는 것을 확인하였다. 분리균주는 16S rDNA 염기서열 분석과 형태학적, 생리학적 특징을 기초로 하여 동정하였다. 분리균주의 165 rDNA염기서열을 기초로한 분자계통학적 분석을 통하여 Bacillus속에 포함하는 계통학적 그룹에 속한다는 것을 확인하였고, Bacillus sp. CHSl으로 명하였다.

• 한국응용곤충학회지
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• 제24권4호
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• pp.219-222
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• 1986

우리나라의 주요(主要) 벼흰잎마름병 저항성(抵抗性) 품종(品種)의 저항성(抵抗性) 유전양식(遺傳樣式)과 저항성(抵抗性) 품종간(品種間)의 대립관계(對立關係)를 분석(分析)하기 위하여 연구(硏究)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. JB8206균주(菌株)에 대(對)한 청청(靑靑)벼, 영풍(永豊)벼, 남풍(南豊)벼, 삼강(三剛)벼, 한강(漢江)찰벼의 흰 잎마름병 저항성(抵抗性)은 1개(個)의 우성유전자(優性遺傳子)에 의(依)해 지배(支配)되었다. 2. JB8206, KN8298균주(菌株)에 대(對)한 백양(白羊)벼와 풍산(豊産)벼의 저항성(抵抗性)은 1개(個)의 우성유전자(優性遺傳子)에 의(依)해 지배(支配) 되었다. 3. JB8206균주(菌株)에 대(對)한 풍산(豊産)벼와 청청(靑靑)벼, 밀양(密陽) 30호(號), 백운(白雲)찰벼의 저항성(抵抗性) 및 수원(水原)312호(號)와 백양(白羊)벼, 백운(白雲)찰벼의 저항성(抵抗性)은 대립관계(對立關係)이었으며 동일유전자(同一遺傳子)로 추정(推定)되었다.