• The Korean Journal of Mycology
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• v.21 no.3
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• pp.195-199
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• 1993

This experiments was designed for development of Fusarium oxysporum strains with enhanced activity of polygalacturonase by means of mutants and protoplasts fusion. Six auxotrophic mutants of F. oxysporum were induced by treatment of MNNG. Protoplasts from mutants were formed from early exoponential mycelium after treatment with driselase(10 mg/ml) using 0.6 M KCl as osmotic stabilizer. Fusion experiments between protoplasts of several auxotrophic mutants were done using polyethyleneglycol 8,000 and $CaCl_2$. The frequency of fusion was $5.0{\times}10^{-3}$ as determined from several experiments. Activity of polygalacturonase was determined by the methods of modified DNS. Consequently, the polygalacturonase activities of mutants and fusant derived F. oxysporum were 1.4 to 3.5 times greater than that of the parental strain, and mutant Fx-2 seemed to be the best strain. Thus, the method we used seemed to be favorable for the improvement of strains.

• The Korean Journal of Mycology
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• v.19 no.4
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• pp.276-281
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• 1991

Auxotrophs induced by UV irradiation were Iysine, arginine, methionine, and cysteine requirement. The optimal protoplast-producing conditions of Pachysolen tannophilus were obtained in 1 hr incubation treated zymolyase 0.5 mg/ml at $37-42^{\circ}C$(pH 6.5-8.5 with 0.6 M KCI as osmotic stabilizer. Cell volumn of fusants were counted in about 4 times of parents and their morphological characteristics were similar to parents which were global or egg-shaped, though in fusant, pseudohypha were observed frequently. Ethanol production of fusants were similar to parents, but arginine and methionine auxotrophs were showed increased ethanol production respectively 1.6 times and 1.25 times more than parents.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.1
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• pp.150-156
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• 1996

유산균의 균주개량방법의 일환으로 photoplast fu-sion 기법과 electrofusion법을 이용하여 protease 활성, lipase 활성, 내열성, 내산성 등이 우수한 L. bulgaricus와 bacteriocin을 생산하는 L. acidophilus 간의 융합시켜 얻은 융합주들의 생리학적 성질을 검토하였다. 산 생성능, 내열성, 내산성 protease, lipase 활성 등 L. bulgaricus가 L. acidophilus보다 우수하였다. L. bulgaricus는 lactose와 sorbos를 이용하였으나. mal-tose 와 dorbitol을 이용하지 못하는 반면 , L. acidophilus는 matose를 이용하고 lactose 와 sorbose를 이용하지 못하였다. 융합주 가운데서는 367810번이 모균주의 발효능 특성을 함께 지님으로서 재조합체임을 확인 할 수 있었으며, sorbitol의 경우 모균주에서는 발효능이 전혀 나타나지 않았음에도 불구하고 융합주 4, 7번이 발효능을 나타내어 융합과정에서 새로운 형질을 획득하기도 한다는 사실을 알 수 있었다. Lactase 활성은 모균주 모두 높은 $\beta-galactosidase$ 활성을 보였으나, $phospho-\beta-galactosidase$ 활성은 거의 없었으며 융합주들도 다소 차이는 있었지만 모균주와 유사한 효소활성을 나타내었다. 발효에 있어서 key enzyme으로 작용하는 protease. lipase 등의 효소활성도 모균주의 활성보다 우수한 융합주도 존재하였다.

• Korean Journal of Food Science and Technology
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• v.41 no.5
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• pp.541-546
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• 2009

The objectives of this study were to evaluate the physico-chemical and sensory characteristics of a Korean traditional alcoholic beverage (yakju) prepared using different nuruk (Korean-style koji) concentrations and yeasts such as the fusant FA776 and Saccharomyces cerevisiae KOY-1, respectively. The fusant FA776, which has alcohol-fermenting and starch-utilizing properties, was formed by Saccharomyces cerevisiae KOY-1 and Saccharomyces diastaticus KCTC1804. The fermentation trial was conducted in a 5 L lab-scale jar at $25^{\circ}C$. The maximum alcohol production of the K-100 and F-50 reached levels of 135.0 mg/mL and 119.4 mg/mL, respectively. The pH values were in a range of 4.3-4.5. Total acidity was in a range of 0.47-0.60%. Organic acids and amino acids were analyzed in order to evaluate variations in its composition and content via HPLC analysis. Organic acids including lactic acid, citric acid, malic acid, and pyruvic acid, and 16 kinds of amino acids, including aspartic acid, were detected in all treatments. K-100 showed the highest amino acid contents, whereas F-50 exhibited the lowest amino acid contents. Volatile flavor components such as phenylethyl alcohol, isoamyl alcohol, 2-methylthiophane, isobutyl alcohol, and ethyl succinate were detected as a major component in all treatments, as determined via gas chromatography. The results of our sensory evaluation demonstrated that Yakju fermented by the FA776 fusant yielded more favorable results than S. cerevisiae KOY-1.

• The Korean Journal of Mycology
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• v.22 no.4
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• pp.378-385
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• 1994

Interspecific somatic hybrids were obtained by protoplast fusion between Pleurotus ostreatus and Pleurotus sajor-caju. The fusion products between incompatible strains did not form clamp connections. Fruiting body of the clampless fusants was induced by light-dark cycle on saw-dust-rice bran substrate in glass bottles. Out of them, seven somatic hybrids produced fruiting bodies of intermediate morphology of the two species. Light and low temperature were the initiating factors for the development of clamped hyphae from the clampless mycelial colonies. All of these basidiocarps had clamp connections. Eight fusants from the six crosses were analysed with the segregation of genetic characters by random spore isolates. In the three combinations, unexpected alleles were shown. Somatic hybrid between P188 (P. ostreatus 2-1 + P. sajor-caju 2-53) and P. florida 2-3 by triple cross produced fruiting bodies similar to those of fusant between P. ostreatus and P. florida. All the genetic charaters from the three strains were shown to segregate and recombine.

• Korean Journal of Microbiology
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• v.28 no.1
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• pp.55-64
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• 1990

Cell volume and DNA contents of the fusants were similar to those of parents. Genetic stability of the fusants was increased when they were cultured on minimal medium (MM) rather than on complete medium (CM), and the fusants were stabilized by subculturing 7 generations each 7 day on MM agar. The finally selected fusants after being cultured for 6 months on CM were stable without segregation. The fusants could also form nuclein and ascospores, and show red and pink colors by the test of TTC colorization. Assimilability and fermentability of carbon sources of the fusants were similarto those of parents. The tolerance of KCl, NaCl, sodium propionate and cycloheximide showed the traits of one strain of parents. When the fusants were cultured for 72 hr and 60 hr in the medium containing 20% glucose and sucrose, respectively, the yield of ethanol for FWKS 260 was reached to 9.6 v/v% and 9.8v/v%, respectively. The sensitive strain Kyokai 7 was found to be killed entirely after cultivation of 48 hr by the killer toxin from the fusants. The recipient S 29 and Kyokai 7 were found to have neither L nor M dsRNA plasmid. However, K 52 and fusants had both L and M dsRNA plasmid of 4.7 kb and 2.5 kb, respectively. The curants treated by heat and cycloheximide did not contain M dsRNA plasmid, but had large amounts of L dsRNA plasmid of those of killer yeasts.

• Microbiology and Biotechnology Letters
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• v.26 no.6
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• pp.490-496
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• 1998

Aspergillus oryzae producing high proteolytic enzyme was isolated from soybean koji and named tentatively A. oryzae O-1. A. oryzae U-1 was obtained by mutation of A. oryzae O-1 with ultraviolet (UV)-irradiation and produced 14 times higher pretense activity compared with A. oryzae O-1. A. oryzae E-1 was acquired by treatment of A. oryzae U-1 with 0.5 M ethylmethanesulfonate (EMS) for 6 min at 3$0^{\circ}C$ and produced 39 times higher proteolytic activity than A. oryzae O-1. With protoplast fusion between A. oryzae O-1 and A. oryzee E-1 in the presence of polyethylenegylcol (PEG)-CaCl$_2$, proteolytic activity was increased to 82 times compared to A. oryzae O-1, and the fusant was named A. oryzae PF. The activities of the cultures containing proteolytic enzymes produced by the strains were determined to be 0.23 U/$m\ell$ for A. oryzae O-1, 3.29 U/$m\ell$ for A. oryzae U-1, 8.91 U/$m\ell$ for A. oryzae E-1, and 19.0 U/$m\ell$ for A. oryzae PF.

• The Korean Journal of Mycology
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• v.17 no.3
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• pp.119-123
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• 1989

Interorder heterokaryons were obtained by polyethylene glycol induced fusion of protoplasts from auxotrophic mutants of Pleurotus ostreatus in agaricales and Ganoderma applanaturm in aphyllophorales. When transferred to MMM plates, all fusion colonies exhibited an extremely growth rate. During three times subcultivation on MCM the growth rate of fusants showed faster little by little. Seventy-five % fusion products of potoplasts showed mixed morphologies between those of P. ostreatus and G. applannatum in the first subcultivation on MCM and MGM. The phenotype of these fusants changed similar those of P. osteatus type after three times subcultivation on MCM. However, phenotype of 25% stable strains did not change on subcultivation. Hyphae of all fusion products did not form true clamp connection. All these types did not produce primordia. A comparrison of interorder somatic hybrids was made using isozyme analysis of esterase, malate dehydrogenase and peroxidase. In most cases the enzyme patterns of G. applanatum were not distinct, however, fusant showed non-parental bands.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.1
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• pp.1-12
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• 1995

This study was to investigate an effective biological control of forage diseases and provide a basic data and a model in improving variety of antagonistic bacteria, with growth promoting effect on forage, through cell fusion. The results obtained were summarized as follows; 1. The antagonistic himbacterium against soil-borne phathogenic fungi Fusarium oxysporum and Rhizoctonia solani was isolated from continuous cropping himsphere soil of forage, and its biological and physiological characteristics were investigated. This bacterium was identified as Bacillus subrilis and named BS 101. Another strain for cell fusion was Bacillus thur ingiensis ssp. kurstaki HD-I(BT 37669) with insecticidal crystal. 2. The auxotropic mutants of BS 101 and BT 37669 were derived after mutagenesis using N-methyl-N'nitro- Nitrosoguanidine(NTG) to give amino acid requirement marker. n e s e auxotropic mutants of BS 101 and BT 37669 were named BS 1013(his-) and BT 69(asp-), respectively. 3. The best protoplast requirement was obtained using DM 3 medium, containing 5% casamino acid, 1 M $MgCI_2$ and 2% bovine semm albumin, to give Fusant 3, 7 and 8. BT toxin gene was not identified with fusants by Southern blotting. However, SDS-PAGE analysis of strains showed various protein patterns among fusants. 4. From the dark culture experiment, growth of forage in inoculated soil with antagonistic bacteria was delayed than that of non-inoculated soil with antagonistic bacteria in each continuous cropping soil and in each sterilized soil. On the other hand, growth duration of forage was different between continuous cropping soil and sterilized soil. 5. Seed germination of Alfalfa, Italian ryegrass and Orchardgrass were significantly improved by inoculation of antagonistic bacteria(p< 0.05).