• Korean Journal of Veterinary Research
• /
• v.42 no.2
• /
• pp.201-208
• /
• 2002

Staphylokinase is seldom formed by animal Staphylococcus aureus strains. In this study, 76(72.4%) of 105 Staph aureus strains isolated from bovine mastitis were found to produce a staphylokinase. These staphylokinase producing strains were tested for lysogenic conversion by means of delysogenization procedure and isolation of serotype B and F converting phages. By the application of delysogenization method comprised of UV irradiation and acriflavine treatment to 76 staphylokinase-positive strains, the delysogenized cells could be observed in 29(38.2%) of the strains and delysogenization rates in 16(55.2%) of 29 delysogenized strains were 0.9% or less. A total of 7 serological group F phages were isolated from 76 staphylokinase-positive strains, and these phages could be again divided into three groups by the immunity reaction. Of 7 serotype F phages, 2 were isolated from the original lysogenic strains producing colonies of delysogenized cells after delysogenizing treatments and 5 were isolated from strains in which delysogenized cells were not observed after delysogenizing treatments. Difference of sensitivities to serological group F phages between original lysogenic strains and strains from which delysogenized cells were not isolated after delysogenizing treatments was not observed These data suggest that staphylokinase production of the remaining 42 strains might be also mediated by lysogenic conversion.

• Journal of Microbiology and Biotechnology
• /
• v.28 no.12
• /
• pp.2064-2070
• /
• 2018

Pseudomonas tolaasii 6264 is a representative strain that causes bacterial blotch disease on the cultivated oyster mushroom, Pleurotus ostreatus. Bacteriophages are able to sterilize the pathogenic P. tolaasii strains, and therefore, they can be applied in creating disease-free mushroom cultivation farms, through a method known as "phage therapy". For successful phage therapy, the characterization of phage-resistant strains is necessary, since they are frequently induced from the original pathogenic bacteria in the presence of phages. When 10 different phages were incubated with P. tolaasii 6264, their corresponding phage-resistant strains were obtained. In this study, changes in pathogenic, genetic, and biochemical characteristics as well as the acquired phage resistance of these strains were investigated. In the phylogenetic analyses, all phage-resistant strains were identical to the original parent strain based on the sequence comparison of 16S rRNA genes. When various phage-resistant strains were examined by three different methods, pitting test, white line test, and hemolytic activity, they were divided into three groups: strains showing all positive results in three tests, two positive in the first two tests, and all negative. Nevertheless, all phage-resistant strains showed that their pathogenic activities were reduced or completely lost.

• Mycobiology
• /
• v.34 no.4
• /
• pp.196-199
• /
• 2006

Effects of various preservation periods and subcultures on fruiting body formation of Cordyceps militaris were investigated using EFCC C-10995 single ascospore strains. Fruiting body formation by original strains was profuse when preserved at $4^{\circ}C$ for $5{\sim}6$ months. Fruiting from subcultures was stable till second to sixth subcultures, after which it decreased sharply. The more the colony color of subcultures changed, the less the fruiting bodies formed. Liquid inoculum preparation of single ascospore strains in the same or separate broths did not affect fruiting body formation. Similarly, two strains C-10995-3 and C-10995-6 in different numbers during liquid inoculum preparation produced similar fruiting bodies.

• YAKHAK HOEJI
• /
• v.2 no.1_2
• /
• pp.41-47
• /
• 1953

"Kimchi" is a most popular pickled Vegetables in Korea. In this paper, eight strains of gram positive rocls and two strains of gram positive cocci are isolated from "Kimchi". For the each isolated strains, the acid production test against carbohydrate and production test of amylase, protease, esterase, and general biological tests are investigated. The most active one for the amylase production is No.2 strain the most active one for the Protease production is No.5,6, and 9 strains. And that for Esterase production is No.9 strain (see the original paper on the results in this journal page)

• 한국균학회소식:학술대회논문집
• /
• 2009.10a
• /
• pp.14-16
• /
• 2009

Poria cocos is an importantant medical macrofungus,the sclerotium of Poria cocos has specific value as the drug material. There are few papers about its breeding and spawn rejuvenation. In this project, the protoplasts of cultivated strain T and wild strain L were prepared and treated separately by ultraviolet and heating, then fused with the PEG6000. The tural fusants were selected and identified by the affinity and ISSR analysis. 71 incompatibility strains between parents and reg regenerations were obtained from 118 regenerations by the affinity analysis. Five incompatibility strains were amplified with different primers, the results were showed that they had specific bands of both parents in the profile amplified with 3 primers, which proved these 5 strains were fusants by means of molecular biology marker. On the other hand, 25 strain were selected from 168 protoplast regenerations of cultivated strain T for cultivation experiment. The fresh sclerotium weight of these protoplast regenerations were better than the original strain.significantil 3 strains (T-1, T-4, T-7) increased respectively 118%, 73% and 73% than original strain. This method could be the effective in the rejuvenation Poria cocos.

• The Korean Journal of Mycology
• /
• v.9 no.2
• /
• pp.93-97
• /
• 1981

The new strains of Mycogone perniciosa which could attack cream colored mushroom were collected and tested to find out their characteristics in comparison with the original strains. The optimum temperature for mycelial growth was $25^{\circ}C$, showing no difference between strains, but optimum pH was 6.0 for the original strains and pH 7.0 for the new ones. New strains did not survive at $50^{\circ}C$ for 60 minutes while original ones 40 minutes. Delan and Hamai were effective for controlling new strains and the mushroom strains which have scales showed resistance to the new strains of Mt. perniciosa regardless of the mushroom colors.

• Korean Journal of Veterinary Service
• /
• v.35 no.3
• /
• pp.169-174
• /
• 2012

Japanese encephalitis virus (JEV) is one of the main causes of viral encephalitis in human and animals. For over 30 years, a live attenuated JEV vaccine strain has been used in the veterinary field, and it is required to conduct quality evaluation studies on the commercial vaccines. For the quality control of live attenuated JEV vaccine, we investigated the nucleotide sequence similarity of prME gene derived from five JEV vaccines commercially available in pigs in Korea. The Vero cells infected with JEV vaccines showed specific cytopathic effect, which was characterized by rounding and detached cells. In the phylogenetic analysis, all of the vaccine strains showed a close relationship with the original vaccine seed strain (Anyang 300) and clustered into the genotype 3. In comparison of the nucleotide and deduced amino acid sequences of prME genes with the original strain, all JEV vaccine strains showed high amino acid similarity ranging from 98.9% to 99.5%, but had several point mutations, probably due to high mutation rates of viral RNA polymerase by several virus passages. Even though the current JEV vaccine strains have been maintained and produced for a long period of time, the genetic characterization of them have been rarely changed. However, since the mid 1990's, molecular epidemiology of JEV has been changed sharply from genotype 3 to genotype 1 in Korea, further studies on new vaccine strains to genotype 1 is required for more effective prevention in the field.

• The Korean Journal of Zoology
• /
• v.14 no.3
• /
• pp.125-131
• /
• 1971

In order to see if NaCl affected the the emergence rate and the SD action when treated it at the pupal stage of Drosophila melanogaster, an experiment was performed in which the resistibility to NaCl at the pupal stage was examined by the emergence rate and the effects of NaCl on the SD action was studied by k values. The four SD strains and two other strains (cn bw and Oregon-R) were used and NaCl media were prepared by adding NaCl at a concentration of 0.0M, 0.1M, 0.3M, 0.5M, 0.7M, and 1.0M to the standard media for the present experiment. The following conclusions were established: 1. The emergence rate (resistibility to NaCl) when treated NaCl at the pupal stage is significantly different not only among the strains but also among concentrations of NaCl. 2. The emergence rate decreases as concentration of NaCl increases but the rate of decrease shows rather constant so that the curves of decrease are not steep. 3. The emergence rate of the cn bw and Oregon-R strains shows higher value than of the four SD strains, implying that the resistibility to the NaCl is lower in the SD strains than in the two strains; not a few flies are emerged from the media of 1.0M of NaCl. 4. The difference in k values is not significant among concentrations of NaCl but among strains, the k values of the original SD strains are rather higher and constant but those of the recombinant SD strains are rather low and unstable. 5. The SD action is not affected by NaCl as far as once emerged from the culture media whether containing NaCl or not in any developmental stage. Thus such an experiment on NaCl effect is of little value to analyze the mechanism of the SD action in D. melanogaster.

• Korean Journal of Veterinary Research
• /
• v.49 no.3
• /
• pp.243-248
• /
• 2009

After the original identification of canine parvovirus (CPV) type 2 (CPV-2) in 1978, new antigenic variants such as CPV-2a, CPV-2b and CPV-2c have become widespread in the most countries. In this study, the genetic analysis of canine parvovirus was investigated in a total of 13 CPV vaccines, which have been licensed in Korea since late 1980s, and a field isolate of CPV from a dog with CPV infection clinical symptom. The partial VP2 gene of CPV was amplified and sequenced from 13 vaccine strains and one field isolate. The results showed that of the 13 vaccine strains, 10 strains belong to the CPV-2, 2 strains to CPV-2b, the remaining and one isolate to CPV-2a type, respectively. Several mutations of amino acids were detected at residues of the critical region of the commercial vaccine strains. These data suggest that new type of vaccines containing CPV-2a or CPV-2b/2c type may be required for the better prevention of new CPV infection in dog population in Korea, because CPV-2 contained in most licensed vaccines has been replaced by antigenic variants designated CPV-2a or CPV-2b/c in the worldwide dog population.

• Korean Journal of Microbiology
• /
• v.28 no.3
• /
• pp.236-242
• /
• 1990

To develop the new strains of microorganisms having the degradative ability for various aromatic hydrocarbons, the hybrid plasmid pKG2 having the 2,4-Dichlorophenoxyacetic acid(2,4-D) degradative genes, the hybrid plasmid pKG3 containg the naphthalene degradative genes and TOL plasmid were introduced into Pseudomonas putida KUD 12 and P. putida KUP 10 by transformation or conjugation which originally have the degradative ability of the synthetic surfactants and phthalate esters, respectively. From P. putida KUD12, the new strains of P. putida KUD101(pKG2), KUD102(pKG3), KUD103(TOL), and KUD202(pKG3, TOL) were obtained, and KUD106(pKG2), KUD107(pKG3), KUD108(TOL) were originated from the P.putida KUP10. The degradative abilities in P. putida KUD101, KUD102 and KUD107 were similar with those of the original strains. The P. putida KUD103, KUD106 and KUD202 had a little lower and P. putida KUD108 had a better degradative abilitie than those of the original ones. In the case of mixed cultures, the mixed culture of KUD107 and KUD108 had a better degradative abilities than those of the other mixed cultures.