• Journal of Microbiology
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• v.44 no.5
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• pp.530-536
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• 2006

Bacteriophage P4, a satellite phage of coliphage P2, is a very useful experimental tool for the study of viral capsid assembly and cos-cleavage. For an in vitro cos-cleavage reaction study of the P2-P4 system, new shortened and selectable markers containing P4 derivative plasm ids were designed as a substrate molecules. They were constructed by swapping the non-essential segment of P4 DNA for either the kanamycin resistance (kmr) gene or the ampicillin resistance (apr) gene. The size of the genomes of the resulting markers were 82% (P4 ash8 delRI:: kmr) and 79% (P4 ash8 delRI:: apr) of the wild type P4 genome. To determine the lower limit of genome size that could be packaged into the small P4-size bead, these shortened P4 plasmids were converted to phage particles with infection of the helper phage P2. The conversion of plasmid P4 derivatives to bacteriophage particles was verified by the heat stability test and the burst size determination experiment. CsCl buoyant equilibrium density gradient experiments confirmed not only the genome size of the viable phage form of shortened P4 derivatives, but also their packaging into the small P4-size head. P4 ash8 delRI:: apr turned out to be the smallest P4 genome that can be packaged into P4-sized head.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.20-20
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• 2015

Endophytic fungi are microorganisms inhabiting living plant tissues without causing apparent harm to the host. They are drawing increasing attention due to their ability to produce various bioactive compounds as well as their effects on host growth and resistance to biotic and abiotic stresses. As a first step to assess biodiversity of plant associated fungi in Korea and the following evaluation on diverse biological activities, we are collecting endophytic fungi from plant in wild followed by systematic long-term storage in liquid nitrogen. Molecular identification using ITS sequences was also incorporated for pure culture by hyphal tip isolation. As of April 2015, about 1,400 fungal strains had been isolated from about 170 plant taxa. Fungal isolates belonging to Pleosporales, Diaporthales, Glomerellales, Hypocreales, and Xylariales were the most abundant. These collections are being used for several complementary researches, including screening of isolates with novel bioactive compounds or conferring drought stress resistance, phylogenetic and genomic study. Genome sequencing was performed for 3 isolates, one Xylaria sp. strain JS573 producing griseofulvin, an antifungal compound, and two Fusarium spp. strains JS626 and JS1030, which are assumed to be new species found in Korea. More detailed analysis on these genomes will be presented. These collections and genome informations will serve as invaluable resources for identifying novel bioactive materials in addition to expand our knowledge on fungal biodiversity.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.709-717
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• 2015

Airborne bacteria from hog farms may have detrimental impacts on human health, particularly in terms of antibiotic resistance and pathogen zoonosis. Despite human health risks, very little is known about the composition and diversity of airborne bacteria from hog farms and hog-related spray fields. We used pyrosequencing analysis of 16S rRNA genes to compare airborne bacterial communities in a North Carolina hog farm and lagoon spray field. In addition, we isolated and identified antibiotic-resistant bacteria from both air samples. Based on 16S rRNA gene pyrosequence analysis, Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria were the dominant phyla in airborne bacterial communities from both hog farm and spray field sites. Within the Firmicutes genera, Clostridium spp. were more abundant in the hog farm, whereas Staphylococcus spp. were higher in the spray field. The presence of opportunitic pathogens, including several Staphylococcus species and Propionibacterium acnes, was detected in both bioaerosol communities based on phylogenetic analysis. The isolation and identification of antibiotic-resistant bacteria from air samples also showed similar results with dominance of Actinobacteria and Proteobacteria in both hog farm and spray field air. Thus, the existence of opportunistic pathogens and antibiotic resistant bacteria in airborne communities evidences potential health risks to farmers and other residents from swine bioaerosol exposure.

• Journal of Environmental Health Sciences
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• v.35 no.4
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• pp.278-286
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• 2009

The total of 181 students in Seoul were made up questions to analysis hand washing awareness from 2007 to 2008. And their hands were sampled to isolate Staphylococcus aureus for testing antibiotic resistance. The average of hand washing frequency was $2.8{\pm}2.6$ per day in their schools. The rates of the students washing hands before eating food, after outdoor activity and after using bathroom were 22.2%, 24.4% and 49.4%, respectively. The rate of students washing hand less than 20 seconds was 64.4%. The students of 43.3% answered that they thought they were washing hands well. The middle school students were worse than elementary and high school students were aware of the frequency, duration and activity of hand washing. The isolation rate of S. aureus on the hands was 29.4%. The isolates were resitant to ampicillin (28.6%), chloramphenicol (6.1%), erythromycin (31.0%), gentamycin (2.0%), penicillin (79.6%) and tetracycline (6.1%) of 17 antibiotics tested. They were all sensitive to oxacillin and vancomycin.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.693-699
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• 1998

Three three hundred and ninety seven isolates of Botrytis cinerea were isolated from infected plants of strawberry, tomato and cucumber from several areas in Korea during 1994∼1996 and the resistance of these isolates against some fungicides were examined. The isolation frequency of phenotypes resistant to carbendazim, procymidone, and diethofencarb were found to be 69.9 43.7, and 31.8%, respectively. The isolates were divided into six phenotypic groups; SSR, SRR, RSS, RRS, RSR and RRR, representing sensitive (S) or resistant (R) to benzimidazole, dicarboximide, and N-phenylcarbamate fungicides in order. The percentage of six phenotypes were 28.2, 2.0, 27.2, 41.0, 0.9 and 0.8%, respectively. On the basis of the mycelial growth inhibition (%) B. cinerea isolates were divided into three classes (class 1; 0∼50%, class 2; 51-99%, class 3; 100% inhibition) on carbendazim and three classes (class 1; 0∼75%, class 2; 76∼99%, class 3; 100% inhibition) on procymidone and the mixture of carbendazim+diethofencarb, respectively. Changes in sensitivity levles to carbendazim and carbendazim+diethofencarb were affected by introduction and increasing ratio of the use of diethofencarb.

• Journal of environmental and Sanitary engineering
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• v.23 no.3
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• pp.31-38
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• 2008

This study was conducted to investigate the effects of environmental factor such as temperature, salinity, turbidity, pH and dissolved oxygen on the growth of Vibrio spp.. In this survey, total 56 seawater samples were obtained from 8 different sites of the Incheon coastal area during the periods from april 2008 to october 2008. Enumeration of Vibrio spp. was determined by using the most probable number(MPN) procedure. Isolation rates of V. parahaemolyticus, V. vulnificus, V. cholerae in all samples tested were 44.0%, 21.4% and 13.1%, respectively. The enumeration of Vibrio spp. was very low correlated with water temperature and pH and negatively correlated with salinity, dissolved oxygen and turbidity. We found salinity to be the parameter most highly correlated with the enumeration of Vibrio spp. The highest rate of antibiotic resistance of V.vulnificus and V.parahaemolyticus was Cefazolin(11.5%), Ampicillin(70.8%), respectively.

• Journal of Microbiology and Biotechnology
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• v.15 no.3
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• pp.491-496
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• 2005

The biosynthetic gene cluster for the aminoglycoside antibiotic kasugamycin was isolated and characterized from the kasugamycin producing strain, Streptomyces kasugaensis KACC 20262. By screening a fosmid library using kasA, the gene encoding aminotransferase, we isolated a 22 kb DNA fragment. The fragment contained seventeen complete open reading frames (ORFs); one of these ORFs, kasD, was identified as the gene for dNDP-glucose 4,6-dehydratase, which catalyzes the conversion of dNDP-glucose to 4-keto-6-deoxy-dNDP-glucose. The enzyme showed a broad spectrum of substrate specificity. In addition, ksR was overexpressed in E. coli BL21 and proved to be a self-resistance gene against kasugamycin. These findings suggest that the isolated gene cluster is highly likely responsible for the biosynthesis of kasugamycin.

• Korean Journal of Veterinary Research
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• v.31 no.3
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• pp.279-284
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• 1991

To investigate the epidemiological aspects of listeriosis, serotypes of L monocytogenes and antimicrobial susceptibilities of Listeria spp isolated from chicken carcases and chicken slaughter house environmental specimens were determined. Of 28 L monocytogenes strains, 12 strains(42.9%) were serotype 4, and the remaining 16 strains were untypable. Peak distributions of minimum inhibitory concentration$({\mu}g/ml)$ of the isolates were $0.78{\mu}g/ml$ for ampicillin, $0.39{\mu}g/ml$ for erythromycin and penicillin G, $1.56{\mu}g/ml$ for tetracycline and $6.25{\mu}g/ml$ or $12.5{\mu}g/ml$ for chloramphenicol, and $3.13{\mu}g/ml$ to > $100{\mu}g/ml$ for kanamycin and neomycin. Most of 214 isolates were sensitive to ampicillin and erythromycin, but 20. 1~78. 0% of the strains were resistant to tetracycline, kanamycin, penicillin-G and neomycin. Single or double drug resistance were observed in 75.8% of the resistant strains. The most common resistance patterns were Nm P-G(37.4%) in double pattern and P-G(23.7%) in single pattern.

• Food Science of Animal Resources
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• v.35 no.5
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• pp.669-673
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• 2015

The aims of this study were to investigate the occurrence of Listeria species in turkey meats and to check the antimicrobial susceptibility of the isolated strains. Hundred and fifteen raw turkey meat samples were randomly collected from the supermarkets, butchers and restaurants. Strain isolation and identification were made according to the ISO11290-1 method. Antimicrobial susceptibility was determined by the standard disc diffusion method. A total of 47 Listeria spp. were isolated from 115 (40.9%) raw turkey meat samples. The isolates were distributed between L. monocytogenes (25.53%), L. innocua (34.04%), L. grayi (31.91%) and L. welshimeri (8.51%). A total of 55.3 % of Listeria spp. isolates were multi-resistant to at least 3 of the antimicrobial agent tested. The level of multi-resistance was higher in L. monocytogenes strains (66.7%) than in L. innocua (62.5%) and L. grayi (53.3%). Listeria spp. isolates were highly resistant to ampicillin, cephalothin, penicillin, meticillin, oxacillin, and trimethoprime-sulfamethoxazole. The isolates particularly L. monocytogenes are increasingly resistant to one or more antibiotics and may represent a potential risk for public health because these antibiotics are common used in treatment of listeriosis. The correct and controlled use of antibiotics in veterinary medicine is important to the emergence of resistant strains.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1123-1126
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• 2011

The IncP plasmid R995 has been a useful self-transmissible, broad-host-range vector for a number of applications including the recombinase/conjugation-based cloning of large genomic DNA segments. However, R995 derivatives (or related plasmids) expressing a wide range of different resistance markers and Flp recombinase target sites do not exist in the literature. In addition, documented strategies for applying such plasmids in cloning applications that take advantage of conjugation for the convenient isolation and recovery of constructs are extremely limited. Here, we report a new series of R995 plasmids with alternative markers to increase options for applications in backgrounds already expressing resistance to a particular antibiotic(s). These R995 plasmids have been engineered to contain FRT sites that can be used for recombinase-based cloning. We demonstrate the utility of this approach by cloning 20 kb regions from the Salmonella Typhimurium and Escherichia coli genomes and by cloning DNA from an exogenous plasmid source. To our knowledge, this represents the first systematic engineering of an intact, self-transmissible IncP plasmid with a series of alternative antibiotic markers and FRT sites.