• Food Science and Biotechnology
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• 제16권1호
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• pp.99-103
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• 2007

The purpose of this study was to develop a simple detection method, possibly at the species-level, that allows for large-scale screening of bifidobacteria. Human fecal samples were plated on MRS-raffinose agar containing cysteine and neomycin sulfate, serving as selective pressure for bifidobacteria, and 0.003%(w/v) bromocresol green. All of the test strains grew well on this medium at $37{\pm}1^{\circ}C$, forming white colonies surrounded by yellow halos, which presented a sharp contrast against the green background. In this disc assay, the required incubation time to develop a yellowish zone varied with the species of Bifidobacterium that was tested, allowing for differential counts and easy identification at the species-level: 10-14 hr for B. bifidum, 20-22 hr for B. catenulatum and B. infantis. and 24-25 hr for B. longum and B. breve. No apparent color was observed for B. angulatum and B. adolescentis 28 hr after inoculation. To evaluate the results of pH indicator-based identification, individual isolates were subjected to a colony-PCR experiment with genus-specific primers. The amplified products from the isolates were in good accordance with those from the reference strains at a level of 95% agreement. These results suggest that the present method could be conveniently applied to cell counts, as well as to the preliminary identification of bifidobacteria from a variety of sample types including human feces, dairy products, and commercial probiotic supplements.

• Journal of Dairy Science and Biotechnology
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• 제39권3호
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• pp.104-112
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• 2021

This study was conducted to evaluate the efficacy of commercial disinfectants at inactivating Enterobacter sakazakii (Cronobacter spp.) in water. Disinfectant I contained 6.15% sodium hypochlorite, and disinfectant II contained both 2.25% n-alkyl dimethylbenzyl ammonium chloride and 2.25% n-alkyl ethylbenzyl ammonium chloride. Disinfectant I was added to distilled water to obtain a range of residual chloride concentrations at 50 ppm intervals with a maximum of 1-1,000 ppm. Disinfectant II was prepared at concentrations ranging from 1-200 ppm with 5 ppm intervals. Exposure time for all solutions was 10 min. In total, 58 E. sakazakii (Cronobacter spp.) strains were tested in this study. Nine isolates were obtained from clinical samples, and 49 isolates were obtained from environmental samples. Seven strains (6 clinical and 1 environmental) were able to survive in 100 ppm disinfectant I, and a maximum of 5 ppm of disinfectant II. Fifty one strains (3 clinical and 48 environmental) were not killed in 10 ppm of disinfectant I and 1 ppm of disinfectant II in water. In conclusion, this study demonstrated that clinical E. sakazakii (Cronobacter spp.) strains displayed 5- to 10-fold higher resistance to disinfectants than environmental E. sakazakii (Cronobacter spp.) strains. Disinfectant II, containing quaternary ammonium compounds, was shown to be more potent in inactivating E. sakazakii (Cronobacter spp.) in water used to clean infant formula manufacturing equipment than disinfectant I.

• Journal of Microbiology and Biotechnology
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• 제29권2호
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• pp.274-282
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• 2019

Mercury-resistant ($Hg^R$) bacteria were isolated from heavy metal polluted wastewater and soil collected near to tanneries of district Kasur, Pakistan. Bacterial isolates AZ-1, AZ-2 and AZ-3 showed resistance up to $40{\mu}g/ml$ against mercuric chloride ($HgCl_2$). 16S rDNA ribotyping and phylogenetic analysis were performed for the characterization of selected isolates as Bacillus sp. AZ-1 (KT270477), Bacillus cereus AZ-2 (KT270478) and Bacillus cereus AZ-3 (KT270479). Phylogenetic relationship on the basis of merA nucleotide sequence confirmed 51-100% homology with the corresponding region of the merA gene of already reported mercury-resistant Gram-positive bacteria. The merE gene involved in the transportation of elemental mercury ($Hg^0$) via cell membrane was cloned for the first time into pHLV vector and transformed in overexpressed C43(DE3) E. coli cells. The recombinant plasmid (pHLMerE) was expressed and the native MerE protein was obtained after thrombin cleavage by size exclusion chromatography (SEC). The purification of fusion/recombinant and native protein MerE by Ni-NTA column, dialysis and fast protein liquid chromatography (FPLC/SEC) involved unfolding/refolding techniques. A small-scale reservoir of wastewater containing $30{\mu}g/ml$ of $HgCl_2$ was designed to check the detoxification ability of selected strains. It resulted in 83% detoxification of mercury by B. cereus AZ-2 and B. cereus AZ-3, and 76% detoxification by Bacillus sp. AZ-1 respectively (p < 0.05).

• Infection and chemotherapy
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• 제50권4호
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• pp.328-339
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• 2018

Background: Pneumococcal disease is a major cause of morbidity and mortality worldwide, especially in patients with comorbidities and advanced age. This study evaluated trends in epidemiology of adult pneumococcal disease in Crete, Greece, by identifying serotype distribution and antimicrobial resistance of consecutive Streptococcus pneumoniae strains isolated from adults during an 8-year time period (2009-2016) and the indirect effect of the infant pneumococcal higher-valent conjugate vaccines 10-valent pneumococcal conjugate vaccine (PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13). Materials and Methods: Antimicrobial susceptibility was performed by E-test and serotyping by Quellung reaction. Multidrug resistance (MDR) was defined as non-susceptibility to penicillin (PNSP) combined with resistance to ${\geq}2$ non-${\beta}$-lactam antimicrobials. Results: A total of 135 S. pneumoniae strains were isolated from adults during the study period. Twenty-one serotypes were identified with 17F, 15A, 3, 19A, and 11A, being the most common. The coverage rates of PCV10, and PCV13 were 17.8% and 37.8%, respectively. PCV13 serotypes decreased significantly from 68.4% in 2009 to 8.3% in 2016 (P = 0.002). The most important emerging non-PCV13 serotypes were 17F, 15A, and 11A, with 15A being strongly associated with antimicrobial resistance and MDR. Among all study isolates, penicillin-resistant and MDR strains represented 7.4% and 14.1%, respectively. Predominant PNSP serotypes were 19A (21.7%), 11A (17.4%), and 15A (17.4%). Erythromycin, clindamycin, tetracycline, trimethoprim-sulfamethoxazole, and levofloxacin resistant rates were 30.4%, 15.6%, 16.3%, 16.3%, and 1.5%, respectively. Conclusion: Although pneumococcal disease continues to be a health burden in adults in Crete, our study reveals a herd protection effect of the infant pneumococcal higher-valent conjugate vaccination. Surveillance of changes in serotype distribution and antimicrobial resistance among pneumococcal isolates are necessary to guide optimal prevention and treatment strategies.

• The Plant Pathology Journal
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• 제37권6호
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• pp.619-631
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• 2021

Alfalfa mosaic virus (AMV), an economically important pathogen, is present worldwide with a very wide host range. This work reports for the first time the infection of Vinca minor and Wisteria sinensis with AMV using RNA sequencing and reverse transcription polymerase chain reaction confirmation. De novo assembly and annotating of contigs revealed that RNA1, RNA2, and RNA3 genomic fragments consist of 3,690, 2,636, and 2,057 nucleotides (nt) for IR-VM and 3,690, 2,594, and 2,057 nt for IR-WS. RNA1 and RNA3 segments of IR-VM and IR-WS closely resembled those of the Chinese isolate HZ, with 99.23-99.26% and 98.04-98.09% nt identity, respectively. Their RNA2 resembled that of Canadian isolate CaM and American isolate OH-2-2017, with 97.96-98.07% nt identity. The P2 gene revealed more nucleotide diversity compared with other genes. Genes in the AMV genome were under dominant negative selection during evolution, and the P1 and coat protein (CP) proteins were subject to the strongest and weakest purifying selection, respectively. In the population genetic analysis based on the CP gene sequences, all 107 AMV isolates fell into two main clades (A, B) and isolates of clade A were further divided into three groups with significant subpopulation differentiation. The results indicated moderate genetic variation within and no clear geographic or genetic structure between the studied populations, implying moderate gene flow can play an important role in differentiation and distribution of genetic diversity among populations. Several factors have shaped the genetic structure and diversity of AMV: selection, recombination/reassortment, gene flow, and random processes such as founder effects.

• 대한의생명과학회지
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• 제28권2호
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• pp.127-136
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• 2022

Uropathogenic Escherichia coli (UPEC) is main causative agent of urinary tract infections. They are classified based on various types of O antigen. UPEC strains commonly possess many genes encoding virulece-associated factors. E. coli strains are generally divided into four main phylogenetic groups. The virulence factor (VF) profiles of UPEC are related with their O-serogroups in each strains. A total of 681 strains of UPEC clinical isolates were collected from Korean healthcare facility (1989: 123 strains and 2010-2014: 558 strains). The UPEC clinical isolates were analyzed by polymerase chain reaction (PCR) methods. A total of 14 O-serotypes (O1, O2, O4, O6, O7, O8, O15, O16, O18, O21, O22, O25, O75 and O83), 6 virulence factors (papC, fimG/H, sfaD/E, hly1, cnf1 and usp) and phylogenetic groups were identified. The most prevalent O-serogroups were O6 (11.1%) in 1989 UPEC strains and O25 (21.0%) in 2010-2014 UPEC strains. The identified VFs, phylogenetic groups in 1989 UPEC strains and 2010-2014 UPEC strains were fimG/H and B2 group. In this study, O6 serotype was revealed the close relationships with VFs. Also, the distribution of prevalence O-serogroups of UPEC has been changed from O6 to O25 and virulence of UPEC strains was increased during past twenty-one years.

• 농업과학연구
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• 제49권1호
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• pp.113-120
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• 2022

Leaf blight disease caused by Stemphylium species is an important disease in Allium crops, specifically onion, garlic and welsh onion. In 2018, leaf blight symptoms were severe and damaged onion and garlic in Jeonnam province in Korea. In addition, small purple spots on garlic burbs were observed in a post-harvest storage warehouse. Several Stemphylium isolates were isolated from diseased leaves from the field and from garlic bulb samples and were analyzed in terms of homology and the phylogenetic relationship based on the internal transcribed spacer region and calmodulin gene sequence. The results showed that among three Stemphylium species identified, S. vesicarium is most prevalent on onion and garlic. S. eturmiunum was for the first time identified as pathogenic to onion and garlic, whereas S. solani was found in welsh onion crops. Although these isolates grew well at the optimum temperature at 20 - 25℃, they could also grow at low temperatures of 10 - 15℃. A pathogenicity test was conducted using S. vesicarium and S. eturmiunum on onion and garlic respectively. These results showed that two Stemphylium species were highly virulent with cross pathogenicity in onion and garlic. The results of this study can support the biological characterization of Stemphylium species in Korea. Moreover, further research will need to develop fungicide application strategies for onion and garlic crops.

• 한국임상수의학회지
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• 제40권6호
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• pp.393-398
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• 2023

We identified mastitis-causing pathogens using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) in an organic dairy farm and evaluated the effects of antimicrobial restriction on antimicrobial susceptibility. A total of 43 Holstein cows without any clinical sign of mastitis were used in this study, and 172 quarter milk samples were cultured on blood agar plates for 24 hours at 37℃. Subsequently, bacterial species were identified and antimicrobial susceptibility tests were performed. The subclinical mastitis infection rates in the cows and quarters were 58.1% (25/43) and 25.6% (44/172), respectively. In the species identification, Staphylococcus aureus (40.9%) was the most prominent isolate, followed by S. chromogenes (22.7%), S. epidermis (18.2%), S. simulans (11.4%), S. haemolyticus (2.3%), S. muscae (2.3%), and S. xylosus (2.3%). In the antimicrobial susceptibility test, all isolates were 100% susceptible to 24 of 28 antibiotics, except for benzylpenicillin, cefalotin, cefpodoxime, and trimethoprim/sulfamethoxazole. The resistance rates of S. aureus, S. chromogenes, and S. muscae isolates to trimethoprim/sulfamethoxazole were 27.8%, 10%, and 100%, respectively, and the resistance rates of S. epidermis and S. xylosus to benzylpenicillin were 50% and 100%, respectively. S. chromogenes, S. epidermis, S. simulans, S. haemolyticus, and S. xylosus were resistant to cefalotin and cefpodoxime. In conclusion, restrictions on antimicrobial use for organic dairy farm certification have resulted in a high Staphylococcus spp. infection rate. Therefore, our study indicates the importance of mastitis management strategies implemented by farmers together with veterinary practitioners, even if mastitis does not appear clinically in organic dairy farms.

• Parasites, Hosts and Diseases
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• 제53권3호
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• pp.259-263
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• 2015

The increasing prevalence of Toxoplasma gondii infection in the human population in the Republic of Korea (= Korea) is due to various reasons such as an increase in meat consumption. However, the importance of cats in transmitting T. gondii infection through oocysts to humans has seldom been assessed. A total of 300 fecal samples of stray cats captured around Seoul from June to August 2013 were examined for T. gondii B1 gene (indicating the presence of oocysts) using nested-PCR. Fourteen (4.7%) of 300 cats examined were positive for B1 gene. Female cats (7.5%) showed a higher prevalence than male cats (1.4%). Cats younger than 3 months (5.5%) showed a higher prevalence than cats (1.5%) older than 3 months. For laboratory passage of the positive samples, the fecal suspension (0.2 ml) of B1 gene positive cats was orally inoculated into experimental mice. Brain tissues of the mice were obtained after 40 days and examined for the presence of tissue cysts. Two isolates were successfully passaged (designated KNIH-1 and KNIH-2) and were molecularly analyzed using the SAG5D and SAG5E gene sequences. The SAG5D and SAG5E gene sequences showed high homologies with the ME49 strain (less virulent strain). The results indicated the importance of stray cats in transmitting T. gondii to humans in Korea, as revealed by detection of B1 gene in fecal samples. T. gondii isolates from cats were successfully passaged in the laboratory for the first time in Korea.

• 한국수산과학회지
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• 제34권4호
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• pp.320-326
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• 2001

어분단백질의 이용성을 높이기 위한 가식성 혹은 생분해성 필름가공을 목적으로 알칼리 처리하여 제조된 FMPI의 물성과 이물성과 ester 화합물의 필름 투과율과 인장강도에 미치는 영향을 조사한 결과는 다음과 같다. 어분으로부터 알칼리처리하고 추출조건을 달리하여 제조된 FMPI의 추출량은 추출시간이 증가함에 따라 증가하였다. FMPI의 소수성은 추출시간 1시간일 때 가장 높게 나타났다가 그 이상 추출시간이 경과함에 따라 감소하였다 유화활성은 추출시간이 5시간까지 증가함에 따라 급격한 증가를 보였으며, 유화안정성은 추출시간 2시간까지 추출시간의 증가에 따라 급격한 감소를 보여 유화활성과 상반된 결과를 나타내었다. 점도는 pH가 2일 때 가장 높게 나타났고 pH가 4일 때 가장 점도가 낮게 나타났다. 첨가하는 가소제의 농도가 증가할수록 필름의 ethyl acetate의 투과도는 증가하였다. 가소제의 종류별에 따른 ethyl acetate의 투과도는 polyethylene glycol, glycerol 및 sorbitol 첨가 필름 순으로 높게 나타났으며, ester 화합물 중에서는 ethyl formate의 투과속도가 가장 높았다. 온도가 증가함에 따라 ethyl acetate의 필름 투과속도는 증가하였다. FHPI의 표면소수성이 증가하면 필름의 인장강도가 증가하였다. 필름의 신장율은 FMPI의 표면소수성보다 가소제의 종류에 더 큰 영향을 받았다.