• The Journal of the Korean Society for Microbiology
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• v.22 no.1
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• pp.95-99
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• 1987

When tetracycline resistancy were cured by ethidium bromide treatment, some of the cured strains lost the tetracycline resistance plasmid while other strains kept the plasmids. Both strains of lost and remained plasmids were digested with restriction endonuclease Hind III and these cleaved plasmids were compared with that of parent strains, two plasmid remained strains showed same cleavage patterns between parent and cured strains, however, one plasmid lost strain showed dissimilarity with parent strain, but in the other one strain, among 4 plasmid lost colonies, 2 showed same but other 2 showed different patterns compared to parent strain. Tetracycline was transfered by conjugation in on set(Staphylococcus aureus donor versus Staphylococcus epidermidis, recipient) with relative high frequency but the other 2 sets showed a low degree of frequency and the other 2 sets exhibited no transfer.

• Journal of Mushroom
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• v.10 no.3
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• pp.101-108
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• 2012

Pleurotus ostreatus 'Miso' is a mutant strain showing white color in pileus from the known parent strain 'Wonhyeong 1'. Shape and several other characters also vary with culture conditions. Mating experiments were performed to understand interstrain mating relationship using monokaryons of the parent and the mutant strains. All monokaryons were grown from single spores isolated from freshly collected fruit bodies. Pairings were performed in 90 mm petri dishes on PDA. They were allowed to grow at 25 until two fronts of the advancing mycelia met and developed a conspicuous contact zone. The contact zone and the outer edges of paired colonies on each plate were examined for clamp connections. The parent and the mutant resulted in tetrapolar incompatibility in intrastrain crosses. In interstrain crosses, each monokaryotic tester strain of the parent strain was out-crossed to monokaryotic tester strains of the mutant. As a result of these crosses it was found that both strains share the same A and B incompatibility factors yielding 25% compatibility.

• Mycobiology
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• v.45 no.1
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• pp.31-38
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• 2017

Cordyceps militaris, known as Dong-Chong-Xia-Cao, produces the most cordycepin among Cordyceps species and can be cultured artificially. For these reasons, C. militaris is widely used as herb or functional food in the East Asia. In this study, we developed a new strain of C. militaris that produces higher cordycepin content than parent strains through mating-based sexual reproduction. Twenty parent strains were collected and identified as C. militaris based on internal trasncrived spacer and rDNA sequences. Seven single spores of MAT 1-1 idiomorph and five single spores of MAT 1-2 idiomorph were isolated from 12 parent strains. When 35 combinations were mated on the brown rice medium with the isolated single spores, eight combinations formed a stroma with a normal perithecia and confirmed mated strains. High pressure liquid chromatography analysis showed that mated strain KSP8 produced the most cordycepin in all the media among all the tested strains. This result showed due to genetic recombination occurring during the sexual reproduction of C. militaris. The development of C. militaris strain with increased cordycepin content by this approach can help not only to generate new C. militaris strains, but also to contribute to the health food or medicine industry.

• Journal of Microbiology and Biotechnology
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• v.9 no.4
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• pp.518-521
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• 1999

Bacillus sp. 79-23 spores were irradiated with $^{60}Co$ gamma-rays at doses ranging from 0.5 to 5 kGy. Following gamma-irradiation, seven mutant strains were isolated by scoring the halo sizes formed around the colonies grown on LB agar plates containing 4% carboxymethylcellulose (CMC) and trypan blue. The mutant strains showed a 1.5 to 2-fold increase in carboxymethylcellulase (CMCase) activity over the parent strain. Wheat bran acted as an effective inducer for CMCase production in the parent and mutant strains. Mutant strains 68 and 70 were identified as exhibiting higher CMCase activities than those of other mutants in LB media both with and without 3% wheat bran. In addition, these strains seem to produce substantially lower amounts of capsular materials, whereas the parent strain produced large amounts of them in both liquid and solid LB media. In flask cultures, the CMCase production by mutants 68 and 70 reached maximum levels of 17.5 unit/ml and 15.7 unit/ml, respectively, in an LB medium containing 3% wheat bran.

• Microbiology and Biotechnology Letters
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• v.22 no.3
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• pp.240-245
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• 1994

Relation the phage defense mechanism of phage resistant Lactococcus lactis subsp. cremoris ATCC 11602-A1 to its cell wall components was investigated. To determine whether teichoic acid which is known to be one of the phage receptor site present on the cell wall, phage adsorption was examined after treatment 5% TCA(60%$\CIRC $C) and concanavalin A to the cell wall of A1 and parent strain. However, the adsorption rate of two strains did not change. Total amount of phosphate after TCA treatment did not change in both strains, but a difference between the two strains was observed. Ribitol and glycerol, components of teichoic acid, could not be detected in the cell walls of two strains by GC analysis. These results suggest that although teichoic acid was not present in the cell walls of both strains, the composition of cell wall of two strains was not identical. Measurement of amount of protein and SDS-polyacryamide gel electrophoresis were carried out to examine the involvement of cell wall protein in phage resistance, showing that protein is nothing to do with phage adsorption of parent strain, but phage resistance of A1 is related to protein. Cell wall carbohydrates of A1 contained rhamnose, glucose, and galactose. Total amount of carbohydrate of 1% SDS-treated A1 cell wall was reduced to the level of parent strain. The results suggest that phage resistance of A1 was due to the presence of a higher level of carbohydrates then parent strain, and to interaction of carbohydrate and protein.

• The Korean Journal of Mycology
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• v.37 no.1
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• pp.65-72
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• 2009

For the breeding purpose, in this study we attempted to select a new Lentinula edodes strain by comparing mycelial growth rate, fruit-body quality and mushroom productivity per substrate weight of hybrid strains with parent strains. Nineteen hybrid strains were made by cross of di-karyotic and mono-karyotic to develop strains suitable for sawdust cultivation of L. edodes. Among the nineteen strains, ten were selected by comparing mycelial growth rate on PDA media and wood rot on sawdust-based substrates. The most mushroom harvesting was achieved by 100 days incubation from KFRI 960, KFRI 961, KFRI 962, KFRI 963, KFRI 964, KFRI 971, KFRI 973 and 125 days from KFRI 968, 970. Experiment of incubation periods with the ten strains showed that there were productivity differences between 100 and 150 days incubations. Through comparison of hybrid strains' mushroom productivity it was found that there was no difference in mushroom productivity through crossing high temperature types with high temperature types, crossing low temperature types with high temperature types and crossing unknown temperature types with high temperature types, but there was difference through crossing middle temperature types with high temperature types. Hybrid strains showed better productivity compared with parent strains. Fruiting temperature type analysis of hybrid strains confirmed that strains of high temperature types have a dominant character.

• YAKHAK HOEJI
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• v.37 no.4
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• pp.350-355
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• 1993

The preparation of Streptococcus faecalis RSI is used as a medicinal preparation for human intestinal disorders. But the microbe in this preparation is very sensitive to rifampicin. If this preparation is taken with rifampicin, its therapeutic effect can not be expected. To develope rifampicin resistant mutants, the rifampicin sensitive strain S. faecalis RSI was treated with Nmethyl-N'-nitro-N-nitrosoguanidine(MNNG). Twelve strains of the MNNG-induced mutants showed distinct resistance to rifampicin and five mutants were selected for further studies. They also exhibited identical characteristics with the parent S. faecalis RSI when they were tested for lactic acid formation and growth inhibition of E. coli. From in vitro test, it was identified that rifampicin is not inactivated by certain factors of the rifampicin resistant mutants. Conclusively, the rifampicin resistant mutants are efficient strains that have insensitivity against rifampicin and original biochemical characteristics of the parent strain.

• Korean Parent-Child Health Journal
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• v.8 no.2
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• pp.97-111
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• 2005

Purpose: The purpose of the study was to analyze the families values of the family with hospitalized children in order to offer descriptive data, which will facilitate family adjustment in those families. Method: It's intended in this study, as of descriptive approach, to verify the theoretical framework based on McCubbin's Resiliency Model and to examine the influence of family values on family adaptation. The survey was conducted from June 20, 2003 to November 30, 2003 and the analysis included 202 parents of the hospitalized children. The data analysis utilized SPSS 11.0 program. Result: The correlation coefficients among major variables showed that family stressor was positively related with family strains(r=.249, P<.01), and negatively related with family hardiness(r=-.183, P<.05). Family strains was negative related with general family value(r=-.243, p<.01), and family adaptation(r=-.505, P<.05). Correlations of general family value was positive with family hardness (r=.153, p<.05), and family adaptation (r=.200, p<.01). Conclusions: There was correlating relationship between family strains and family adaptation, and general family value showed correlation with family strains, family hardiness, and family adaptation. Theresfore the continuing future research on the relationship between family value and family adaption is necessary.

• Journal of Microbiology and Biotechnology
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• v.7 no.1
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• pp.25-31
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• 1997

Protoplast fusion between L. casei KCTC 1121 and L. acidophilus 88 was attempted to obtain improved strains. The fusants produced a bacteriocin against indicator strains, making a smaller inhibition zone compared to that of L. acidophilus 88. After culturing for 2 months on selective medium, the selected fusants were still stable without segregation. Fusants showed higher lipase activity compared to those of the two parent strains. Fusant No.4, 11, and 15 exhibited excellent lactic acid productivity. Fusant No.4 and 15 exhibited improved proteolysis ability compared to the two parent strains. Whereas L. casei possessed both ${\beta}-galactosidase$ and $phospho-{\beta}-galactosidase$ activities, and L. acidophilus 88 had only ${\beta}-galactosidase$ activity, the fusants had both the intermediate enzyme activities. Cell size of the fusants was greater than that of the parents.

• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.215-220
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• 1990

Prophage cured strain derivatives from Luctobacillirs araei YIT 9018 were isolated from thermoinducible mutant of the parent lysogenic strain. Two thermoinducible mutants were isolated from L. casei YIT 9018 strain treated with N-methyl-N'-nitro-N-nitrosoguanidine. Prophage cured strains were selected after heat induction of thermoinducible strains at $42^{\circ}C$ for 30 min in MRT medium containing anti- 4 FSV serum. The prophage cured strains, L. casei HYM 1213 and L. casei HYM 4024, could be used an indicator strain for temperate phage $\phi$ FSW. The growth, lactic acid producing ability and carbohydrates fermentation of L. casei HYM 1213 were similar to the parent L. cmei YIT 9018 strain, but A. casei HYM 4024 was not. One of the prophage cured strain, L. cmei HYM 1213, could be used industrially .to produce lactic acid beverages because this strah could not induce the virulent phage$\phi$FSV. The physiological characterization of L. casei HYM 1213 strain was similar to the parent L. casei YIT 9018 strain.