• Korean Journal of Veterinary Research
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• v.21 no.2
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• pp.93-97
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• 1981

It has long been believed for the presence of infectious coryza affecting serious economic loss in domestic poultry industry. However, the etiologic agent has not been isolated until quite recently. From 1979, several strains of Haemophilus-like organism were isolated from chickens with symptoms similar to infectious coryza, and their colonial morphology, growth requirement, biochemical properties and pathogenicity were assessed. In addition, serological properties of the isolates by cross hemagglutination inhibition test was also investigated. The results indicated that all the isolates were identified as Haemophilus gallinarum which had similar characteristics to the reference strains.

• Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.159-170
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• 2024

Research to obtain molecular markers related to the major histocompatibility complex (MHC) gene in both strains of gourami is essential to increase the success of the selection program of disease resistance traits. Using a completely randomized design (CRD), the challenge test consists of four treatments and seven replications. The treatment was Jambi gourami injected with PBS (KJ), Kalimantan gourami injected with PBS (KK), Jambi strain injected with Aeromonas hydrophila (GJ), and Kalimantan strain injected with A. hydrophila (GK). The GJ population was more resistant to A. hydrophila than the GK population. The MHC II gene was detected in both test strains (GJ and GK), both resistant and susceptible fish. However, there were differences in the results of amplifying the MHC II gene in susceptible and resistant fish. Two DNA fragments approximately 400 and 585 bp were detected in the genome of susceptible fish, while in the genome of susceptible fish, only one DNA fragment was detected (400 bp). Therefore, the MHC II gene fragment with a size of about 585 bp can be used as a potential candidate for specific molecular markers to obtain resistance to A. hydrophila bacteria in the giant gourami.

• Journal of Mushroom
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• v.12 no.3
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• pp.171-180
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• 2014

The primary objective of the present study is the characterization of the hybrids of monokaryon- monokaryon (mono-mono) crosses in mushroom breeding. We employed this technique for developing superior strains from Pleurotus species strains with 85 mono-mono intraspecific hybrids of 7 combinations between six Pleurotus ostreatus strains and one Pleurotus florida strain. In this study, the results of analysis on hybridization rate, nuclear DNA patterns, and colors and yields of fruit-bodies, are presented as follows. The crossability between mono-mono crossing ranges between 50 and 93.75%. The results of the analysis on the nuclear DNA patterns of 85 hybrid strains of mono-mono crosses share the nuclei of both parents, but their genetic similarities were predominated by either parent. The hybrid strain between P. florida and P. ostreatus showed patterns more similar to P. florida, while the hybrid strain between P. ostreatus and P. ostreatus either had patterns predominated by either parent strain. The fruiting body colors of the mono-mono crosses mostly had combined colors of both parents but showed the tendency of being more similar to that of either parent. 82% of the hybrid strain indicated similar fruiting body yields compared to both parent strains, while 0% was higher and 18% were lower than both parents. The present study was able to find out and suggest superior hybrid trains by identifying the nuclear DNA patterns of hybrids between Pleurotus species as well as the characteristics of their fruiting bodies. This study expects that the advantages of the mono-mono crossing are needs to be fully utilized in mushroom breeding and it is better to develop superior strains of Pleurotus species strains together with the mono-mono crossing.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.53-53
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• 2015

Agrobacterium tumefaciens-mediated transformation(ATMT) of Flammulina velutipes was used to produce a diverse number of transformants to discover the functions of gene that is vital for its variation color, spore pattern and cellulolytic activity. Futhermore, the transformant pool will be used as a good genetic resource for studying gene functions. Agrobacterium-mediated transformation was conducted in order to generate intentional mutants of F. velutipes strain KACC42777. Then Agrobacterium tumefaciens AGL-1 harboring pBGgHg was transformed into F. velutipes. This method is use to determine the functional gene of F. velutipes. Inverse PCR was used to insert T-DNA into the tagged chromosomal DNA segments and conducting sequence analysis of the F. velutipes. But this experiment had trouble in diverse morphological mutants because of dikaryotic nature of mushroom. It needed to make monokaryotic fruiting varients which introduced genes of compatible mating types. In this study, next generation sequencing data was generated from 28 strains of Flammulina velutipes with different phenotypes using Illumina Hiseq platform. Filtered short reads were initially aligned to the reference genome (KACC42780) to construct a SNP matrix. And then we built a phylogenetic tree based on the validated SNPs. The inferred tree represented that white- and brown- fruitbody forming strains were generally separated although three brown strains, 4103, 4028, and 4195, were grouped with white ones. This topological relationship was consistently reappeared even when we used randomly selected SNPs. Group I containing 4062, 4148, and 4195 strains and group II containing 4188, 4190, and 4194 strains formed early-divergent lineages with robust nodal supports, suggesting that they are independent groups from the members in main clades. To elucidate the distinction between white-fruitbody forming strains isolated from Korea and Japan, phylogenetic analysis was performed using their SNP data with group I members as outgroup. However, no significant genetic variation was noticed in this study. A total of 28 strains of Flammulina velutipes were analyzed to identify the genomic regions responsible for producing white-fruiting body. NGS data was yielded by using Illumina Hiseq platform. Short reads were filtered by quality score and read length were mapped on the reference genome (KACC42780). Between the white- and brown fruitbody forming strains. There is a high possibility that SNPs can be detected among the white strains as homozygous because white phenotype is recessive in F. velutipes. Thus, we constructed SNP matrix within 8 white strains. SNPs discovered between mono3 and mono19, the parental monokaryotic strains of 4210 strain (white), were excluded from the candidate. If the genotypes of SNPs detected between white and brown strains were identical with those in mono3 and mono19 strains, they were included in candidate as a priority. As a result, if more than 5 candidates SNPs were localized in single gene, we regarded as they are possibly related to the white color. In F. velutipes genome, chr01, chr04, chr07,chr11 regions were identified to be associated with white fruitbody forming. White and Brown Fruitbody strains can be used as an identification marker for F. veluipes. We can develop some molecular markers to identify colored strains and discriminate national white varieties against Japanese ones.

• BMB Reports
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• v.37 no.3
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• pp.282-291
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• 2004

Phytases catalyze the release of phosphate from phytic acid. Phytase-producing microorganisms were selected by culturing the soil extracts on agar plates containing phytic acid. Two hundred colonies that exhibited potential phytase activity were selected for further study. The colony showing the highest phytase activity was identified as Aspergillus niger and designated strain 113. The phytase gene from A. niger 113 (phyI1) was isolated, cloned, and characterized. The nucleotide and deduced amino acid sequence identity between phyI1 and phyA from NRRL3135 were 90% and 98%, respectively. The identity between phyI1 and phyA from SK-57 was 89% and 96%. A synthetic phytase gene, phyI1s, was synthesized by successive PCR and transformed into the yeast expression vector carrying a signal peptide that was designed and synthesized using P. pastoris biased codon. For the phytase expression and secretion, the construct was integrated into the genome of P. pastoris by homologous recombination. Over-expressing strains were selected and fermented. It was discovered that ~4.2 g phytase could be purified from one liter of culture fluid. The activity of the resulting phytase was 9.5 U/mg. Due to the heavy glycosylation, the expressed phytase varied in size (120, 95, 85, and 64 kDa), but could be deglycosylated to a homogeneous 64 kDa species. An enzymatic kinetics analysis showed that the phytase had two pH optima (pH 2.0 and pH 5.0) and an optimum temperature of $60^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1218-1223
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• 2012

${\varepsilon}$-Poly-$_L$-lysine (${\varepsilon}$-PL), produced by Streptomyces or Kitasatospora strains, is a homo-poly-amino acid of $_L$-lysine, which is used as a safe food preservative. The present study investigates the combined use of cell immobilization and in situ adsorption (ISA) to produce ${\varepsilon}$-PL in shaken flasks. Loofah sponge-immobilized Streptomyces ahygroscopicus GIM8 produced slightly more ${\varepsilon}$-PL than those immobilized on synthetic sponge, and sugarcane bagasse. Moreover, loofah sponge supported the maximum biomass. Hence, loofah sponge was chosen for cell immobilization. Meanwhile, the ion-exchange resin D152 was employed for ISA. The loofah sponge-immobilized cells produced $0.54{\pm}0.1g/l$ ${\varepsilon}$-PL, which significantly increased to $3.64{\pm}0.32g/l$ after combining with ISA through the addition of resin bags. The free cells with ISA using the dispersed resin yielded $2.73{\pm}0.26g/l$ of ${\varepsilon}$-PL, an increase from $0.82{\pm}0.08g/l$. These data illustrate that the proposed combination method improved production most significantly compared with either immobilization or ISA only. Moreover, the immobilized cells could be repeatedly used and an ${\varepsilon}$-PL total amount of $8.05{\pm}0.84g/l$ was obtained. The proposed combination method offers promising perspectives for ${\varepsilon}$-PL production.

• The Korean Journal of Mycology
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• v.39 no.1
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• pp.48-52
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• 2011

Breeding of Lentinula edodes generates a number of hybrid strains that are subject to evaluation for good traits for the mushroom production. As an effort to understand biochemical properties of the hybrid strains, this study tried to develop a fast and easy method for comparison of the ability of producing extracellular laccase among hybrid strains of Lentinula edodes. For this aim, we estimated the effect of media types and chromagenic chemicals on the detection of extracellular laccase in seven hybrid strains of L. edodes. When Remazol Brilliant Blue R (RBBR) dye was used for chromagenic reaction, the detection of the enzyme activity was feasible both in the solid and liquid media containing not potato dextrose but malt extract as a nutrient component. When guaiacol was used for chromagenic reaction, the detection of the enzyme activity was feasible both in the solid and liquid media containing either potato dextrose or malt extract as a nutrient component. Malt extract-based liquid culture with RBBR or guaiacol in 2 ml microfuge tube allowed us to economically and quantitatively detect and compare the enzyme activity within 3 days among the tested hybrid strains of L. edodes.

• Journal of Life Science
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• v.30 no.11
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• pp.1007-1011
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• 2020

This study was conducted to analyze the genetic diversity and relationships that discriminate between Korean native black goat populations (Dangjin, Jangsu, Tongyoung, and Gyeongsang National University strains) and crossbred goats. Monomorphic single nucleotide polymorphisms (SNPs) in each strain were collected, and 133 common SNPs were selected for analysis. These 133 monomorphic SNPs showed differences in the genetic structure of the Korean native black goat and crossbred goats, and results from the principal component analysis (PCA) showed that the two can be clearly separated. Furthermore, analysis of the validation population comprising 70 individuals (Korean native black goats, n = 24; crossbred goats, n = 46) with the reference population showed that Korean native black goat strains and the reference population have the same genetic structure, and the crossbred goats shared only part of the genetic structure with the reference population. The result of the PCA analysis showed that the Korean native black goat strains form one population, whereas the foreign strains form another population which is more widely dispersed than the Korean native black goat strains. Thus, the results from this study can be used as baseline data for the conservation of genetic resources of Korean native black goat communities through utilization of monomorphic SNPs and for the introduction of exotic species for further improvement in genetic diversity. This study can also help reduce unnecessary inbreeding and gene flow between native strains.

• Research in Plant Disease
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• v.12 no.2
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• pp.129-133
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• 2006

A bacterial disease of small red bean (Phaseolus angularis) was observed on field-grown plants in Suwon in year 2003. Leaf symptoms initially appeared as water-soaked spots that gradually enlarged, became flaccid and necrotic and were often bordered by a small zone of lemon yellow tissue. In the case of severe infection, dead leaves were defoliated. Pod symptoms consisted of the lesions that were generally circular, slightly sunken and dark reddish brown. Isolation made from diseased leaves on yeast extract dextrose calcium carbonate agar yielded nearly pure cultures of a yellow-pigmented bacterium typical of a xanthomonad. Three bacterial strains were purified and used for further tests. Pathogenicity of strains was confirmed on 3-week-old small red bean plants sprayed with bacterial suspensions containing $10^8 cfu/ml$ of phosphate buffered saline. The representative Xanthomonas strains isolated from small red bean were compared with X. axonopodis pv. phaseoli and X. axonopodis pv. phaseoli var. fuscans type strains for fatty acid profiles, biochemical tests and metabolic fingerprints using Biolog GN2 microplate, showing that all outcomes were indistinguishable between our isolates and reference strains. Two of three strains produced a melanin-like brown pigment extracellularly on King's medium B agar. These results suggest that this new small red bean disease observed in Suwon is bacterial fuscous blight caused by X. axonopodis pv. phaseoli and X. axonopodis pv. phaseoli var. fuscans.

• Journal of Microbiology and Biotechnology
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• v.33 no.6
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• pp.831-839
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• 2023

Tylosin is a potent veterinary macrolide antibiotic produced by the fermentation of Streptomyces fradiae; however, it is necessary to modify S. fradiae strains to improve tylosin production. In this study, we established a high-throughput, 24-well plate screening method for identifying S. fradiae strains that produce increased yields of tylosin. Additionally, we constructed mutant libraries of S. fradiae via ultraviolet (UV) irradiation and/or sodium nitrite mutagenesis. A primary screening of the libraries in 24-well plates and UV spectrophotometry identified S. fradiae mutants producing increased yields of tylosin. Mutants with tylosin yield 10% higher than the wild-type strain were inoculated into shake flasks, and the tylosin concentrations produced were determined by high-performance liquid chromatography (HPLC). Joint (UV irradiation and sodium nitrite) mutagenesis resulted in higher yields of mutants with enhanced tylosin production. Finally, 10 mutants showing higher tylosin yield were re-screened in shake flasks. The yield of tylosin A by strains UN-C183 (6767.64 ± 82.43 ㎍/ml) and UN-C137 (6889.72 ± 70.25 ㎍/ml) was significantly higher than that of the wild-type strain (6617.99 ± 22.67 ㎍/ml). These mutant strains will form the basis for further strain breeding in tylosin production.