• Research in Plant Disease
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• v.8 no.1
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• pp.66-69
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• 2002

In February of 2002, the gray mold disease occurred severely on primular(primular spp.) grown in a flower nursery farm in Jinju, Korea. At first, the infected leaves were discolored to gray or dark from the tip and gradually expanded to die. The fungus attacked not only leaves but petals, calyx flower stalk and stems. Conidia of the fungus in mass were hyaline or gray, 1-celled, mostly ellipsoid or ovoid and sized 6.8~16.9$\times$4.6~12.4 $\mu$m. Conidiophores were wide of 15.9~31.6$\mu$m in size. The sclerotia were readily formed potato-dextrose agar and optimum temperature far sclerotial formation was 2$0^{\circ}C$. Pathogenecity of the causal organism was and preyed according to Koch\`s postulate. The causal organism was identified as Botrytis cinerea based on mycological characteristics. This is the first report on gray mold of primula caused by Botrytis cinerea in Korea.

• Korean Journal of Veterinary Research
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• v.38 no.1
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• pp.53-63
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• 1998

Total of 1085 swine sera (1996-1997) from nation-wide were tested for the presence of antibodies to influenza A virus. Fifty nine percent of the tested sera showed seropositive by HI test. Positive sera consisted of 24--- of H3, 15--- of H1, and 20--- of the sample had both antibodies, respectively. Sera collected from various region represented 7~27--- seropositivity to H1N1, 15~25--- to H3N2, respectively. Swine influenza field isolate from nasal swab was characterized antigenically and genetically to elucidate its relatedness with other known strains of influenza A virus. The study was focused on the HA gene which is related to pathogenecity and antigenic variability of the influenza virus. By RT-PCR using influenza A/H1N1 specific primers, influenza virus H1N1 specific DNA fragment was amplified from A/Swine/Iowa/15/30(H1N1), US field isolate but not in H3N2 strain. PCR products were sequenced by dideoxy chain termination method to determine nucleotide homology with other strains of influenza A virus. The US field isolate and A/Swine/Indiana/1726/88 strain had 97--- of nucleotide homology and 98--- of amino acid homology. Based on the results obtained from this experiment, the field isolate was genetically related to A/Swine/Indiana/1726/88 and had higher homology with A/Swine/Indiana/1726/88 than with classical swine influenza virus, A/Swine/Iowa/15/30. The field isolate had no amino acid changes at the antigenic site compare to that of the A/Swine/Indiana/1726/88. The proteolytic enzyme cleavage site between HA1 and HA2 had no alteration and the amino acid arginine was intact. There is no evidence has been found that the field isolate has genetic shift or genetic drift which might altered antigenic determinant.

• Journal of Dairy Science and Biotechnology
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• v.23 no.1
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• pp.65-71
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• 2005

Powered infant formula and baby food contaminated with Enterobacter sakazakii were reported to cause infection among infants and to be associated with sporadic cases and outbreaks of sepsis, menigitis, cerebritis, and necrotizing enterocolitis. Salmonella contamination of infant formula has also been responsible for multiple outbreaks. Other species of Enterobacteriaceae in powdered infant formula may be causative agents, about which there has been no report. Other pathogenic bacteria have been isolated from powdered infant formula but they were not associated with outbreaks among infant. While Enterobacter sakazakii caused disease in all age groups, premature infants under 28 days old and with birth weight are most sensitive to its infection. Even if low contamination level of the bacteria in powdered infant formula and baby food may not cause infection, the possibility to multiplicate during preparation and storage of reconstituted formula may increase. The etiological factors and pathogenecity of S. sakazakii have not been elucidated. There were wide variability in phenotype and genotype between its strains. S. sakazakii has been isolated from factory facility and surroundings more frequently than Salmonella and thus factory environment should be the source for post-processing contamination of the formula with S. sakazakii. Considering current technology to manufacture power infant formula and baby food it is impossible to sterilize powdered formula but the frequency of outbreak hazard by S. sakazakii can be reduced by pasteurizing the formula base before drying and shortening storage time of the reconstituted formula.

• Research in Plant Disease
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• v.9 no.1
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• pp.25-27
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• 2003

In 2002, a stem rot disease was found on Pansy (Viola tricolor) in several road-side flower beds in Jinju City, Gyeongnam province, Korea. The typical symptoms of the disease were stem rot, crown rot, wilt or blight. Upper parts of the infected stems were mostly blighted. White mycelial mats were spread over lesions and the sclerotia were farmed on the stems near soil line. The sclerotia was globoid or irregular in shape, 1.3~4.2 mm in size, and brown in color, The optimum temperature for fungal growth was about 3$0^{\circ}C$. The typical clamp connections were found in the hyphae of the fungus grown on PDA, and hyphal diameter was 3.9~10.4 ${\mu}{\textrm}{m}$. On the basis of mycological characteristics and pathogenecity test on host plants, the fungus was identified as Sclerotium rolfsii. This is the first report on the stem rot of Viola tricolor caused by Sclerotium rolfsii in Korea.

• The Korean Journal of Mycology
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• v.29 no.2
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• pp.131-133
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• 2001

A destructive collar rot disease was found on broad bean (Vicia faba) in several farmer's field located in Changseon-myon, Namhae-gun, Gyeongsangnam-do in 2001. The typical symptoms of the disease were stem rot, crown rot, wilt or blight. Upper parts of the infected stems were mostly blighted and white mycelial mats were spread over lesions and the sclerotia were formed on the stems near soil line. The infection rates of the disease in the surveyed area were ranged from 28.6 to 42.8%. The sclerotia of the fungus readily formed in artificial media such as PDA at $30^{\circ}C$ and its shape was globoid or irregular and size was $1.0{\sim}3.7{\times}1.0{\sim}2.8\;mm\;(av.\;1.0{\sim}2.3\;mm)$ and was brown or dark brown in color. The optimum temperature for growth of the fungus was about $30^{\circ}C$. The typical clamp connections were found in the hypha of the fungus grown on PDA. On the basis of mycological characteristics and pathogenecity test on host plants, the fungus was identified as Sclerotium rolfsii. This is the first report on the collar rot of broad bean caused by Sclerotium rolfsii in Korea.

• Research in Plant Disease
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• v.9 no.2
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• pp.85-88
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• 2003

A sclerotinia rot of Water cress (Oenanthe javanica) occurred in the commerical farmers field at Garye-myon, Uiryeong-gun, Gyeongnam Province, Korea, 2002. The typical symptoms appeared on leaves and stems. At first, the infected leaves or stems turned dark green later become watery soft rotted; white fluffy mycelia grew from the lesion, later formed black sclerotia. Sclerotia on the infected plants and PDA medium were globose to cylindrical or irregular in shape and 1.0~10.7 ${\times}$1.0~7.6 mm in size. Cup-shaped aphothecia with numerous asci were formed from sclerotinia and the size were 0.4~1.6 cm in diameter. Asci with 8 spores were cylindrical and 74~236 ${\times}$ 4.2~24.8 m in size. Ascospores of one cell were hyaline, ellipsoid to ovoid in shape, and 8.3~12.4 ${\times}$ 3.6~7.2 m in size. The optimum temperature for mycelial growth was $25^{\circ}C$ , and sclerotinia forma-tion was between 15~$20^{\circ}C$. On the basis of mycological characteristics and pathogenecity test to host plants, the fungus was identified as Sclerotinia sclerotiorum. This is the first report of Sclerotinia sclerotiorum caused sclerotinia rot on Oenanthe javanica caused by in Korea.

• Korean Journal of Veterinary Research
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• v.40 no.3
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• pp.543-549
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• 2000

The pathogenicity of Br abortus RB51 strains, producted by commercial vaccine companies in Republic of Korea and USA, were evaluated in mouse and guinea pig. BALB/c and ICR mice were intraperitoneally inoculated with RB51 vaccines or virulent field strain and the existence of RB51 including its ratio of spleen to weights and persistence in spleens were examined. Groups of guinea pigs on day 55-58 of received subcutaneously with various RB51 vaccines, RB51 field isolates (Daehungjin) or virulent field isolates(Sangju) to compare the histopathogenicity in uterus. All the mice received RB51 vaccines or RB51 field isolates survived for 10 days, but the groups of mice received virulent field isolates died 5 from 11 (45.5%) in case of BALB/c mice and 12 from 12 (100%) in ICR mice, respectively. The number of RB51 in the groups of mice given with vaccine strains and RB51 field isolates were declined rapidly were in spleens between 12 and 20 days after inoculation. In contrast the mice given with the virulent field isolates rose in number of bacteria up to 20 days after inoculation. In the groups of mice infected with virulent field isolates, the ratio of spleen weights to body weight were significantly higher than those in control or in the groups inoculated with RB51 strain, including RB51 field isolates, at 12 and 20 days after inoculation. At ten days after inoculation, placentas of both the pregnant and non-pregnant guinea pigs were conducted for histopathological examination. Although any abnormal lesions were not observed in non-pregnant guinea pigs, all the strains caused the inflammation of the placenta, implying pathogenecity of RB51 in pregnant guinea pigs.

• Korean Journal of Veterinary Research
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• v.40 no.3
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• pp.533-541
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• 2000

Biochemical and genetic analysis were carried out to investigate the potential recovery of pathogenecity or related mutations of Brucella abortus RB51 vaccine strains. RB51 strains were recovered from commercial vaccines, including related seed stocks from private companies in Republic of Korea, strain from USA, a reference strain from C university and a field isolate (Daehungjin) from aborted dairy cow after RB51 vaccination were compared with two identified virulent wild strains (S2308 and a field strain isolated from dairy cow in Korea) at the same conditions. All the strains examined, except identified pathogenic strains, revealed the identical characteristics to the original RB51 in biochemical properties, antigen and bacteriophage typing. Outer membrane protein (OMP) profiles from strains of RB51 showed the same patterns with standard RB51 in SDS-PAGE. In addition, Western blotting with the brucella specific monoclonal antibody also indicated that all the vaccine strains were completely deficient in their LPS compared to the pathogenic Br abortus strains. The differences in DNA structures among strains were also possible to detect after PCR. All vaccine strains, except S19, S1119-3, S1075, S544 and Br suis, were amplified a 178bp DNA fragment of eri-gene, and 364bp of IS711 elements. In contrast, 498bp DNA product was only found with Br abortus. Overall evidences in the present study confirmed that the RB51 strains for vaccine production in Korea did not originated from the phenomena of possible recovery of pathogenicity or related to any potential mutation event at all.

• Microbiology and Biotechnology Letters
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• v.35 no.1
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• pp.1-10
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• 2007

The 44 endophytic bacterial strains were isolated from surface-sterilized root of rice cultivated in seven different locations of Chungcheong province, Korea. Each isolate was introduced into rice seedlings grown gnotobiotically by inoculating scissor-cut first true leaf with cell suspensions, and the colonization capacity of each isolate in root tissue was analyzed at 7 days after inoculation. Sixteen out of 44 isolates were re-isolated from root successfully with the frequency of $10^{3-5}$ CFU/g tissue. Interestingly, seven out of 16 isolates were identified as Burkholderia species. The identity between inoculated strains and re-isolates was confirmed by genomic finger-printing and 16S rDNA sequence analysis. By a confocal laser scanning microscopic observation it was revealed that KJ001 strain, one of the sixteen isolates tagged with gfp colonized in root tissue especially around xylem. Six out of seven Burkholderia strains obtained in this study showed antagonizing activities against seven different fungal pathogens, contain nifH gene, and five of them enhanced growth of cucumber over 30%. The isolates showed no hypersensitive response on tobacco leaves and no pathogenecity in rice. From these results it was found that the endophytic Burkholderia strains will be useful in agriculture to develop a biocontrol agent or a bio-fertilizer.

• Research in Plant Disease
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• v.9 no.4
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• pp.217-220
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• 2003

A severe fruit rot of Persimmon (Diospyros kaki cv: Fuyu) was occurred during the storage and transport that infected with blue mold in Sweet Persimmon Experiment Station, Gyeongsangnam-do Agricultural Research and Extension Services, Korea. Fruit surfaces were infected with the fungus first and the colonized fungus formed mycelial mats. From the point of infection, fruits become collapsed and mostly ruptured. The pathogenic fungus from infected fruits was isolated and cultured on PDA. Colony color of the fungus was white at frist than became green on Malt Extract Agar and Czapek Yeast Extract Agar. Conidia were ellipsoid subglobose and 2.6${\sim}$3.8 ${\times}$ 2.4${\sim}$3.8 ${\mu}m$ in size. Stipes were 86${\sim}$320 ${\times}$ 2.8${\sim}$4.3 ${\mu}m$ in size. Rami were 7.5${\sim}$32.6 ${\times}$ 2.6${\sim}$4.2 ${\mu}m$ in size, Ramuli were 12.4${\sim}$14.8 ${\times}$ 3.2${\sim}$3.8 ${\mu}m$ in size, Metulae were 8.9${\sim}$13.6 ${\times}$ 2.8${\sim}$4.6 ${\mu}m$ in size. Phialides were ampulliform, 8.2${\sim}$12.4 ${\times}$ 2.3${\sim}$3.6 ${\mu}m$ in size. Based on the cultural and mycological characteristics and pathogenecity test on host plants, the fungus was identified as s, This is the first report on the blue mold of Persimmon (Diospyros kaki) caused by P. crustosum in Korea.