• Applied Biological Chemistry
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• v.40 no.1
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• pp.65-70
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• 1997

Among 980 fungal strains isolated from the lesions of Trifolium repens L. and various weeds, three Penicillium sp. F40362, F40496, F40497 were selected by the first selection test and a pathogenicity test. The spores of these strains germinated readily 90 to 100% and readily infected the respective plant. The wheat bran-corn starch formulation of F40362 strain showed 100% mycoherbicidal activity against clover plant at $4{\times}10^8$ spores/pot. The same formulations of F40496 and F40497 strains showed 100% mycoherbicidal activity against clover plant at $12{\times}10^8{\sim}4{\times}10^8$ spores/pot. The same formulations of tee strains showed over 30% mycoherbicidal activity against Leguminosae plants. This method of pelletiation was potentially useful for the production of inoculum formulation as mycoherbicides and it was effective enough to treat $2{\sim}2.5\;g$ formulation($4.5{\times}10^7\;spores/mg$) to a $350\;cm^2$ pot. The three strains, F40362, F40496 and F40497 have selective mycoherbicidal activity between Trifolium repens L. and Zoysia japonica and nonselective mycoherbicidal activities against some other crop plants and weeds.

• Korean Journal of Veterinary Research
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• v.42 no.2
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• pp.241-251
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• 2002

Modified-live (ML) infectious laryngotracheitis (ILT) vaccines have been widely used as a preventive measure in Korea since the first outbreak of ITL. Recently, it has been observed that chickens vaccinated with the commercially available ML ILT vaccine have sometimes exhibited adverse clinical signs. In this study, we evaluated the quality of the vaccines by comparing titer of each vaccine batch and testing the stability of ILT virus (ILTV) in vaccine diluents and compared the safety and efficacy of vaccines in specific pathogen free (SPF) chickens. The ratio of maximum titer to minimum titer of vaccine produced by most manufacturers was 2 to 15. However, 2 out of 11 manufacturers produced vaccines of which the ratio was 74 to 478. Most vaccines examined were maintained vaccine titers suitable for national regulations within expiry date. However, some vaccines did not keep the titer required for the national regulations. In the test for stability of ILTV in various diluents, ILTV was highly stable in lactose-phosphate-glutamine-gelatin solution, sucrose-phophate-glutamine-albumin solution and some vaccine diluents produced by manufacturers. The safety of ML ILT vaccines was assessed in 10-day-old SPF chicks. Mortality in SPF chicks inoculated intratracheally with one dose of vaccine varied depending on vaccines and some vaccines produced 50-85% mortality. Seven-week-old SPF chickens were vaccinated intraocularly with ML ILT vaccines and then challenged intratracheally with ILT challenge virus 14 days after vaccination. The protection rate was assessed by clinical signs and reisolation of the ILT challenge virus from tracheas taken at day 4 after challenge. There were slight respiratory reactions in some vaccinated chickens after vaccination but these reactions disappeared within 5 days after vaccination. No further clinical signs and death were observed. Protection rate determined by clinical signs and mortality was 100% in all vaccinated groups. However, the challenge virus was isolated from all tracheas of chickens vaccinated with vaccine B or control groups. The challenge virus was also isolated in the trachea of one in five chickens vaccinated with either vaccine F or K, but not in tracheas of chickens vaccinated with other vaccines. In the present study, the stability of vaccine diluents, pathogenicity and protection rate based on reisolation test of the challenge virus were different depending on vaccines produced by eleven manufacturers.

• Research in Plant Disease
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• v.24 no.4
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• pp.328-331
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• 2018

A severe disease with leaf spots and necrotic symptoms was observed in cucumber (Cucumis sativus L.) seedlings in April 2018 at a nursery in Kimjae, Korea (35o 47'09.8"N 127o 2'24.3"E). The infected plants initially showed spots on water-soaked cotyledons which, at later stages, enlarged and spread to the leaves, which the lesions becoming dry and chlorotic. The symptomatic samples were collected from cucumber and the isolates were cultured on LB agar. The representative bacterial strain selected for identification showed fluorescent on King's medium B, was potato rot-positive, levan and arginine dihydrolase-negative, oxidase-negative and tobacco hypersensitivity-positive in LOPAT group 2 as determined by LOPAT tests. A pathogenicity test was carried out on a 3-week-old cucumber. After 3 days of inoculation, leaf spots and necrotic symptoms appeared on the cucumber, similar to the originally infected plants. The infecting bacterial strain was identified as Pseudomonas viridiflava, by 16S rDNA sequence analysis. This is the first report of leaf spot diseases on cucumber caused by P. viridiflava.

• Research in Plant Disease
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• v.18 no.4
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• pp.317-323
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• 2012

The study aims to identify the pathogenicity of Phytophthora. capsici isolates in major pepper-producing areas in Korea and the inherit genetic pattern of phytophthora blight resistance by inocula. With five kinds of testing materials including 'Kataguma (Sakata Korea)' peppers, a disease-susceptible material, '#308', a phytophthora blight resistance material, 'CM334', and their $F_1$ and $F_2$, respective isolates of P. capsici obtained from Icheon, Eumseong, Buan, Imsil and Yeongyang regions together with six kinds of peppers' inoculum including PA-159 (KACC No.40482) received from Korean Agricultural Culture Collection were used for inoculation. The disease-susceptible material '#308', the resistant material 'CM334' and the non-segregating generation of $F_1$ represented 4.94-5.00, 1.00-1.07, and 1.01-1.08 phytophthora blight incidence respectively in the group comparison by isolate. This result means that the phytophthora blight resistance was clearly distinguished among testing materials in the group comparison by P. capsici isolate. Moreover, $F_2$ segregating generation showed 1.79-2.31 phytophthora blight incidence which turned out to be identical in the group comparison by the six isolates of P. capsici isolate and with similarity between both the resistant and susceptible materials. Thus, the result proved that using the six isolates of P. capsici tested as inocula was suitable to investigate the phytophthora blight resistance. When it comes to group comparison of $F_2$ segregation generation, however, isolates were divided with PA-159 isolate being the center: a group consisting of isolates from Icheon, Buan, and Imsil and a group consisting of Yeongyang and Eumseong isolates with higher pathogenicity. The expected segregation ratio of the phytophthora blight resistance in $F_2$ generation by isolate was analyzed. PA-159 isolate showed 3:1 or 9:3:3:1, indicating that one to two genes were involved. On the other hand, results also proved that there is an interaction of genes since both Eumseong and Yeongyang isolates showed a segregation ratio of 11:5 while the Icheon isolate represented 12:3:1.

• The Korean Journal of Mycology
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• v.16 no.4
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• pp.220-225
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• 1988

This study was carried out to investigate the effect on the system of crop rotation of sesame(Sesamum indicum L). The results of infected plant percentage and yield of sesame wilting disease, fluctuation of density of Fusarium oxysporum and Actinomycetes, and their pathogenicity test on Fusarium spp isolated from sesame cultural soil were investigated. Density of F. oxysporum was the highest in a sesame continuous cropping soil but that of Actinomycetes was the lowest in that soil. And that of F. oxysporum and Actinomycetes according to investigation date was the highest at June. 30 and July. 30, respectively. Their pathogenicity of F. oxysporum and F. solani isolated from sesame cultural soil to sesame, peanut and green gram were recognized to all isolates except one isolate among F. oxysporum 8 isolates and one isolate to sesame, 2 isolates to peanut and all isolates to green gram among F. solani 4 isolates. F. oxysporum density and infected plant of wilting disease were increased as a result of replanted cultivation of sesame, and yield of that was prominantly reduced. Relation between density of F. oxysporum in cultural soil and infected plant percentage showed positive correlation and yield index highly negative. There was little difference between sesame-upland rice and sesame-peanut in the system of crop rotation.

• Journal of fish pathology
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• v.30 no.2
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• pp.89-96
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• 2017

The majority of freshwater ornamental fish are imported and distributed domestically, causing high risk of exposure to exotic pathogens and drug resistant bacteria in Korea. Aeromonas hydrophila is known as a common species of fresh water bacteria and opportunistic fish pathogen, as well as a species causing zoonotic infection. In this study, we isolated motile aeromonads from various imported freshwater ornamental fish and studied the characters of the isolates. Imported freshwater ornamental fish were purchased on day 1 after the fish were deposited in the aquarium. Bacteria were isolated from the liver, kidney and spleen of fish using 0.5% NaCl containing tryptic soy agar medium. Bacteria were grouped on the basis of their morphological characteristics. The colonies with clear zone on starch-ampicillin agar (SA agar) were tentatively identified as Aeromonas spp. Two hundred and twenty-six strains, about 70% of total isolates were assumed to be Aeromonas spp. Nine isolates were further identified based on the result of the API 20E test and PCR using primers specific for A. hydrophila 16S rRNA gene. The isolates were identified as A. hydrophila and the API 20E test showed differences in trisodium citrate, D-sucrose, D-melibiose, amygdalin and L-arabinose availability between the nine isolates and standard A. hydrophila. The susceptibilities of the isolated bacteria to 10 antibacterial agents were confirmed by the disk diffusion method. Isolated strains were found to be resistant to amoxicillin and ampicillin and sensitive to florfenicol. However, 7 isolates showed multiple drug resistances to erythromycin, oxytetracycline, nalidixic acid etc. Pathogenicity of the isolates was determined by the artificial challenge test on goldfish (Carassius auratus). Three isolates caused 60 ~ 80% mortality in goldfish within 5 days after the initiation of challenge. These results indicate that multiple drug resistant, highly pathogenic and exotic A. hydrophila can spread to domestic aquarium and the preventive treatment of fish before sale is necessary.

• Journal of Aquaculture
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• v.21 no.4
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• pp.325-330
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• 2008

Two different Eelwardsiella tarda isolates, KFE and Edk-2, were obtained from Korea and Japan respectively. On the base of the previous results showing higher pathogenicity of E. tarda KFE compared to that of E. tarda Edk-2 isolate, we tried to determine the differences of antigenicities of these two isolates in loach which is one of the important species in freshwater aquaculture in Korea. Concentration of specific antibody in the serum appeared to be much higher in loach immunized with FKC of E. tarda Edk-2 than those found in loach immunized with FKC of E. tarda KFE. Cross-reaction analysis using agglutination test with normal and antigen-absorbed antisera implied the differences epitopes in the antigens of these E. tarda isolates. For the comparison of bactericidal activity of the produced antibody with different antigens, absorption analysis was performed and confirmed the presence of critical epitopes in the FKC of E. tarda KFE strain. The prophylactic agent, polysaccharide-bound protein (PS-K) injected 1 week before the artificial infection with E. tarda KFE isolates decreased the cumulative mortality in loach and would be on effective method to prevent the occurrence of bacterial infection including E. tarda.

• Research in Plant Disease
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• v.20 no.1
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• pp.50-53
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• 2014

Rhizopus soft rot of lily (Lilium longiflorum) caused by Rhizopus oryzae was observed in the experimental field in Taean Lily Experiment Station in Korea, 2012. The typical symptoms were water-soaked lesions on bottom stem and leaf rot. The lesion rapidly expanded and the plant was softened totally. The fungus grew vigorously at an optimum temperature ($25^{\circ}C$) and brownish colony and black sporangia were formed on potato dextrose agar medium. Sporangiophores formed on end of sporangia were sub-globose, brownish and $6-10{\mu}m$ in size. Sporangia were globose, blackish and $87-116{\mu}m$ in size. Sporangiospores were irregularly oval and sub-globose, brownish $4-8{\mu}m$ in size. On the basis of mycological characteristics, analyzing sequences of internal transcribed spacer region of ribosomal DNA, and pathogenicity test on host plants, the causal fungus was identified as R. oryzae. This is the first report of Rhizopus soft rot on lily caused by R. oryzae in Korea.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.775-779
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• 2003

Cultivation environment for effective production of shrimp in shrimp aquaculture, Institute of Marine & Fishery, Soonchunhyang University located at Tae-An, Chung-Nam Province, with the ultimate aim of probiotics development, was monitored. Several environmental factors including dissolved oxygen, water body temperature, pH, salinity, $NH_4-N$, $NO_2-N$, $NO_3-N$, chlorophyll a affecting on the growth of shrimp were examined. Concentrations of $NH_4-N$, $NO_2-N$, and $NO_3-N$ dissolved in water samples were determined to 0.024-0.034 mg/L, 0.03-0.02, and 0.004-0.009 mg/L, respectively. Chlorophyll a content was examined in the range of 0.002-0.118 $ug/m^3$. In order to understand the distribution of different bacteria in water samples collected in shrimp aquaculture, bacteria were isolated and enumerated on the marine agar plates. Total number of bacteria were increased to approximately $6.5\;{\times}\;10^4$. Thirteen predomonant bacteria were isolated and identified. As the results of BIOLOG test of the isolates, these bacteria were identified as Corynebacterium nirilophilus, Clavibacter agropyri, Sphingomonas adhaesiva, Brevundimonas vesicularis, Vibrio parahaemolyticus, Pseudomonas bathycetes, Vibrio tubiashii, Sphingomonas macrogoltabidus, Rhodococcus, rhodochrous, Burkholderia glumae, Corynebacterium urealyticus, Rhodococcus fascians, Psychrobacter immobilis, respectively. Further work will stimulate the elucidation of pathogenicity, corresponding bacteria related to environment and probiotics, providing good information for effective production of shrimp.

• Research in Plant Disease
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• v.10 no.4
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• pp.290-296
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• 2004

Bacterial blossom blight is one of the most important diseases of kiwifruit (Actinidia deliciosa). The disease occurs during flowering in the late May and disease outbreaks associated with rainfall during the flowering season have resulted in a severe reduction in kiwifruit production. The causal organism isolated from diseased blossoms of kiwifruits was identified as Pseudomonas syringae pv, syringae based on the physiological and biochemical characteristics and pathogenicity test. Dead fruit stalks, dead pruned twigs, fallen leaves and soils mainly provided R syringae pv. syringae with overwintering places in the kiwifruit orchards, and the inocula also overwintered on buds, trunks, branches, and twigs on the kiwifruit trees. Among the overwintering places, the incula were detected in the highest frequencies from dead fruit stalks. The population density of P. syringae pv. syringae was speculated to be over $1{\times}10^4$cfu/ml for the bacterial infection, and the optimum temperature for the bacterial growth ranged 20 to $25^{\circ}C$. The highest population density of P. syringae pv. syringae on the overwintering places was detected in May and June when the daily average temperature coincided with the optimum temperature for bacterial growth of P. syringae pv. syringae.