• Korean Journal of Microbiology
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• v.46 no.2
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• pp.207-212
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• 2010

A bacterium producing the extracellular mannanase was isolated from Korean soybean paste. The isolate WL-8 has been identified as Bacillus subtilis on the basis on its 16S rRNA sequence, morphology and biochemical properties. The mannanase productivity of strain WL-8 was increased in LB broth by addition of wheat bran. The maximum mannanase productivity was reached to approximately 20 U/ml in LB medium supplemented with 6% wheat bran. A gene encoding the mannanase of WL-8 was cloned into Escherichia coli and its nucleotide sequence was subsequently determined. The mannanase gene consisted of 1,086 nucleotides encoding a polypeptide of 362 amino acid residues. The deduced amino acid sequence was highly homologous with those of several mannanases from B. subtilis belonging to GH family 26. Reaction temperature and pH profiles were investigated using the culture filtrate and cell-free extract of the recombinant E. coli carrying a WL-8 mannanase gene, respectively. Optimal conditions for the two fractions occurred at pH 5.5 and $60^{\circ}C$. The cell-free extract showed higher mannanase activity than the culture filtrate at above $60^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.7
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• pp.1037-1047
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• 2017

Objective: Despite an increasing number of investigations into the pathophysiology of necrotic enteritis (NE) disease, etiology of NE-associated diseases, and gene expression profiling of NE-affected tissues, the microRNA (miRNA) profiles of NE-affected poultry have been poorly studied. The aim of this study was to induce NE disease in the genetically disparate Fayoumi chicken lines, and to perform non-coding RNA sequencing in the intestinal mucosal layer. Methods: NE disease was induced in the Fayoumi chicken lines (M5.1 and M15.2), and non-coding RNA sequencing was performed in the intestinal mucosal layer of both NE-affected and uninfected chickens to examine the differential expression of miRNAs. Next, quantitative real-time polymerase chain reaction (real-time qPCR) was performed to further examine four miRNAs that showed the highest fold differences. Finally, bioinformatics analyses were performed to examine the four miRNAs target genes involvement in the signaling pathways, and to examine their interaction. Results: According to non-coding RNA sequencing, total 50 upregulated miRNAs and 26 downregulated miRNAs were detected in the NE-induced M5.1 chickens. While 32 upregulated miRNAs and 11 downregulated miRNAs were detected in the NE-induced M15.2 chickens. Results of real-time qPCR analysis on the four miRNAs (gga-miR-9-5p, gga-miR-20b-5p, ggamiR-196-5p, and gga-let-7d) were mostly correlated with the results of RNAseq. Overall, ggamiR-20b-5p was significantly downregulated in the NE-induced M5.1 chickens and this was associated with the upregulation of its top-ranking target gene, mitogen-activated protein kinase, kinase 2. Further bioinformatics analyses revealed that 45 of the gene targets of gga-miR-20b-5p were involved in signal transduction and immune system-related pathways, and 35 of these targets were predicted to interact with each other. Conclusion: Our study is a novel report of miRNA expression in Fayoumi chickens, and could be very useful in understanding the role of differentially expressed miRNAs in a NE disease model.

• Journal of Species Research
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• v.5 no.1
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• pp.166-178
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• 2016

An outcome of the study to discover indigenous prokaryotic species in Korea, a total of 26 bacterial species assigned to the classes Bacteroidetes and Firmicutes were isolated from diverse environmental samples collected from soil, tidal flat, freshwater, seawater, wetland, plant roots, and fermented foods. From the high 16S rRNA gene sequence similarity (>99.0%) and formation of a robust phylogenetic clade with the closest species, it was determined that each strain belonged to each independent and predefined bacterial species. There is no official report that these 26 species have been described in Korea; therefore 14 strains for the order Flavobacteriales and two strains for the order Cytophagales were assigned to the class Bacteroidetes, and 8 strains for the order Bacillales and 4 strains for the order Lactobacillales were assigned to the class Firmicutes are reported for new bacterial species found in Korea. Gram reaction, colony and cell morphology, basic biochemical characteristics, isolation source, and strain IDs are also described in the species description section.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.3
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• pp.423-432
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• 2013

Zi geese (Anser anser domestica) belong to the white geese and are excellent layers with a superior feed-to-egg conversion ratio. Quantitative gene expression analysis, such as Real-time qRT-PCR, will provide a good understanding of ovarian function during egg-laying and consequently improve egg production. However, we still don't know what reference genes in geese, which show stable expression, should be used for such quantitative analysis. In order to reveal such reference genes, the stability of seven genes were tested in five tissues of Zi geese. Methodology/Principal Findings: The relative transcription levels of genes encoding hypoxanthine guanine phosphoribosyl transferase 1 (HPRT1), ${\beta}$-actin (ACTB), ${\beta}$-tubulin (TUB), glyceraldehyde-3-phosphate-dehydrogenase (GADPH), succinate dehydrogenase flavoprotein (SDH), 28S rRNA (28S) and 18S rRNA (18S) have been quantified in heart, liver, kidney, muscle and ovary in Zi geese respectively at different developmental stages (1 d, 2, 4, 6 and 8 months). The expression stability of these genes was analyzed using geNorm, NormFinder and BestKeeper software. Conclusions: The expression of 28S in heart, GAPDH in liver and ovary, ACTB in kidney and HPRT1 in muscle are the most stable genes as identified by the three different analysis methods. Thus, these genes are recommended for use as candidate reference genes to compare mRNA transcription in various developmental stages of geese.

• Journal of Marine Bioscience and Biotechnology
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• v.7 no.2
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• pp.42-51
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• 2015

The community structure of cultivable bacteria associated with the marine sponge, Petrosia corticata, collected from Jeju Island in summer (September) of 2012 and winter (January) of 2013, were compared by the PCR-ARDRA method. Bacterial strains were cultured for 4 days at $26^{\circ}C$ on Zobell medium and marine agar medium. After PCR amplification of 16S rRNA gene of individual strains, the restriction enzymes MspI and HaeIII were used to make restriction patterns. As a result, 24 ARDRA patterns from the summer sponge and 20 ARDRA patterns from the winter sponge were obtained. The sequencing result of 1-3 selected strains from each pattern showed over 98% similarities with the known sequences from the public database. At the phylum level, the bacterial community structures of both sponges (summer and winter) were identical qualitatively and composed of 4 phyla : Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes. Alphaproteobacteria accounted for 42.5% of total in summer sponge and 25.2% in winter, decreasing in the winter sample. Gammaproteobacteria accounted for 27.5% of total in summer sponge and 35.2% in winter, increasing in the winter sample. At the genus and species level, summer sponge had more diverse bacterial communities than winter sponge. Actinobacteria, Bacteroidetes, and Firmicutes increased in the winter sample.

• Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.109-116
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• 2013

Eighteen specimens of juvenile Mugilidae were collected in October 2012 from the southern coastal waters of Jeju Island, and identified based on analysis of their mitochondrial DNA16S rRNA sequences. Seventeen specimens of Oedalechilus labiosus and a single specimen of Ellochelon vaigiensis were found, constituting a new record for these species among Korean ichthyofauna. O. labiosus is identified by the angle at the posterior end of its mouth, which contains a round notch, a darkish dorsal margin of the pectoral fin, the presence of 33-36 lateral line scales, and 23-24 vertebrae. E. vaigiensis is identified by dark dorsal and pectoral fins, the presence of 26 lateral line scales, and 25 vertebrae. The proposed Korean name for Oedalechilus is 'Sol-ip-sung-eo-sok' and that for Ellochelon is 'Nup-jeok-ggo-ri-sung-eo-sok'. The proposed Korean names for the species are 'Sol-ip-sung-eo' and 'Nup-jeok-ggo-ri-sung-eo' for O. labiosus and E. vaigiensis, respectively. We present a key for identification of the Mugilidae family of species from Korea, and include these two newly recorded species.

• Korean Journal of Environmental Agriculture
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• v.39 no.1
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• pp.26-35
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• 2020

BACKGROUND: Microbes that govern a unique biochemical process of oxidizing ammonia into dinitrogen gas, such as anaerobic ammonium oxidation (anammox) have been reported to play a pivotal role in agricultural soils and in oceanic environments. However, limited information for anammox bacterial abundance and distribution in the terrestrial habitats has been known. METHODS AND RESULTS: Phylogenetic and next-generation sequencing analyses of bacterial 16S rRNA gene were performed to examine potential anammox bacteria in paddy soils. Through clone libraries constructed by using the anammox bacteria-specific primers, some clones showed sequence similarities with Planctomycetes (87% to 99%) and anammox bacteria (94% to 95%). Microbial community analysis for the paddy soils by using Illumina Miseq sequencing of 16S rRNA gene at phylum level was dominated by unclassified Bacteria at 33.2 ± 7.6%, followed by Chloroflexi at 20.4 ± 2.0% and Acidobacteria at 17.0 ± 6.5%. Planctomycetes that anammox bacteria are belonged to was 1.5% (± 0.3) on average from the two paddy soils. CONCLUSION: We suggest evidence of anammox bacteria in the paddy soil. In addition to the relatively well-known microbial processes for nitrogen-cycle, anammox can be a potential contributor on the cycle in terrestrial environments such as paddy soils.

• Mycobiology
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• v.48 no.2
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• pp.122-132
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• 2020

Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH₄Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH₄)₂ SO₄ as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.

• Korean Journal of Organic Agriculture
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• v.26 no.1
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• pp.129-140
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• 2018

Pectobacterium carotovorum subsp. carotovorum was found to be highly virulent to various vegetables, including Chinese cabbage. The antibacterial isolate CAB12243-2 was tested in a field bioassay for suppressing soft rot disease. The nucleotide sequencing of the 16S rRNA gene identified, the CAB12243-2 strain used in this study as Bacillus toyonensis. B. toyonensis CAB12243-2 inhibited the pectate lyase process by soft rot pathogens, and used trehalose and glucose as carbon sources. In field tests, the antibacterial isolate B. toyonensis CAB12243-2 suppressed soft rot disease with 73.0% control efficacy on the spring cultivar "Norangbom" and with 68.9% efficacy on the fall cultivar "Bulam 3". These results suggest that B. toyonensis CAB12243-2 can be used as a biological control agent for the control of soft rot diseases on vegetables.

• Journal of fish pathology
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• v.26 no.3
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• pp.207-217
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• 2013

Recently high mortality of cultured olive flounder, Paralichthys olivaceus occurred frequently at the fish farms in Ulsan, Korea. The diseased fish showed skinny body and swimming behavior around the water surface with liver atrophy and white enteritis as internal signs. The isolated bacteria were identified to V. scophthalmi by biochemical test, nucleotide analysis of 16S rRNA and dnaJ gene sequencing. The pathogen of this study showed strong pathogenicity as 75% mortality to olive flounder by intraperitoneal injection of $1{\times}10^6$ CFU/fish. The pathological sign was not different between the naturally diseased fish and the artificially infected fish. Histopathological changes were shown to liver atrophy, desquamation of the intestinal mucosa and hyaline droplet like as other previous studies.