• Journal of Life Science
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• v.24 no.6
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• pp.694-699
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• 2014

Indigenous microorganisms play decisive roles in biodegradation. In this study, eighty strains of hydrocarbon-degrading microbes were isolated from Incheon Bay. Among them, 12 strains were selected by an oil film collapsing method. The bacterial strain 'Incheon9' was eventually selected based on its relatively higher lipase and emulsification activities, and was identified as Acinetobacter sp. (NCBI accession code: KF54854). The optimum condition for the growth and emulsification activity of Acinetobacter sp. Incheon9 was $20^{\circ}C$, pH 7, and 1% NaCl. The optimum time for the best production of biosurfactant was 72 hrs. The oil degradation ability of Acinetobacter sp. Incheon9 was investigated by measuring the residual oils in the culture medium by gas chromatography (FID). This research provides foundational data for eco-friendly environmental remediation by microorganisms.

• Korean Journal of Microbiology
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• v.52 no.2
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• pp.183-191
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• 2016

Marine bacteria have represented unique physiologies and products which are not discovered from terrestrial organisms. There has been great interest to utilize and develop marine bacteria in many industrial sectors. Recently, we isolated and characterized anaerobic bacteria from various marine environments in Korea to search organic acids fermenting strains. From our enrichment performed under anaerobic condition, 65 strains were isolated and identified by the 16S rRNA gene sequence analysis. Among them, eleven strains were selected for phylogenetical and biochemical analysis. All tested strains were affiliated with Class Clostridia except one with Class Bacteroidia. Most of strains produce acetate (6 strains) with butyrate (2 strains) and/or formate (4 strains). Strain MCWD5 transformed 40% of glucose to extracellular polymeric substances. These results indicate that many novel anaerobic microorganisms which have great potential in commercial application are distributed in the marine environments of Korean Peninsula.

• Journal of Environmental Science International
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• v.19 no.10
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• pp.1307-1314
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• 2010

This study was conducted to isolate and characterize a novel feather-degrading bacterium producing keratinase activity. A strain K9 was isolated from soil at poultry farm and identified as Xanthomonas sp. K9 by phenotypic characters and 16S rRNA gene analysis. The cultural conditions for the keratinase production were 0.3% fructose, 0.1% gelatin, 0.04% $K_2HPO_4$, 0.06% $KH_2PO_4$, 0.05% NaCl and 0.01% $FeSO_4$ with an initial pH 8.0 at $30^{\circ}C$ and 200 rpm. In an optimized medium containing 0.1% chicken feather, production yield of keratinase was approximately 8-fold higher than the yield in basal medium. The strain K9 effectively degraded chicken feather meal (67%) and duck feather (54%), whereas human nail and human hair showed relatively low degradation rates (13-22%). Total free amino acid concentration in the cell-free supernatant was about 25.799 mg/l. Feather hydrolysate produced by the strain K9 stimulated growth of red pepper, indicating Xanthomonas sp. K9 could be not only used to increase the nutritional value of chicken feather but also a potential candidate for the development of natural fertilizer applicable to crop plant soil.

• Journal of Environmental Science International
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• v.29 no.5
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• pp.435-443
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• 2020

The purpose of this study was to investigate eco-friendly measures to manage major diseases which cause heavy economic damages to ginseng. Morphological, physicochemical, and molecular biological species identification was carried out after isolating useful antagonistic bacteria from ginseng fields. In addition, optimal conditions for mass culture were established, and he efficacy of the bacteria in the prevention of the diseases was verified in the field. The results showed that about 150 bacteria were extracted from 150 ginseng fields in the whole county. Among them, B. pyrrocinia LA101 was finally selected, which had a strong antagonistic potency against Alternaria panax, Botrytis cinerea, Rhizoctonia solani, and Cylindrocarpon destructans on agar media. The B. pyrrocinia LA101 is a baculiform gram-negative bacterium identified as Burkholderia pyrrocinia according to results from an API(Analytical Profile Index) kit, 16S rRNA, and gyrase gene sequencing analysis. It was donated to the microbe bank of the Agricultural Genetic Resources Center at the National Academy of Agriculture Science under the Rural Development Administration on September 28, 2011 (Donation No. KACC91663P). A patent for the mass culture technology was granted in August 2012 (Patent No. 10-1175532).

• KSBB Journal
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• v.26 no.2
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• pp.100-106
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• 2011

Strain BCNU 5011 was isolated from forest soil samples collected in the Taebaek mountain in the Gangwon province, Korea. The biochemical, physiological and 16S rRNA sequence analysis strongly indicated that this isolate was most closely related to Paenibacillus polymyxa. A maximum production level of antimicrobial substances of Paenibacillus sp. BCNU 5011 was achieved under aerobic incubation at $30^{\circ}C$ for 3 days in SST broth.Paenibacillus sp. BCNU 5011 showed a broad spectrum of activity against Gram positive and Gram negative bacteria, including methicllinresistant Staphylococcus aureus (MRSA). Paenibacillus sp. BCNU 5011 was also shown to inhibit the growth of different potential human pathogenic bacteria and fungi in vitro. Peptide extract showed better antimicrobial activity than solvent extracts. But active antimicrobial compounds might be included in both peptide extract and solvent extracts. Further separation, purification and identification of active principles leads project to develop antimicrobial agents and anti-MRSA agents.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.509-516
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• 2009

The CJ6 bacterial strain, which possesses strong antifungal activity, was isolated from meju and identified as Bacillus polyfermenticus based on Gram staining, biochemical properties, and 16S rRNA gene sequencing. B. polyfermenticus CJ6 showed antimicrobial activity against the various pathogenic molds, yeasts, and bacteria. Antifungal activity from B. polyfermenticus CJ6 was reduced after 24 hr at $70^{\circ}C$ but antifungal activity was not completely destroyed. The antifungal activity was stable in the pH range of $3.0{\sim}9.0$, and inactivated by proteinase K, protease, and ${\alpha}$-chymotrypsin, which indicate its proteinaceous nature. The apparent molecular masses of the partially purified antifungal compound, as indicated by using the direct detection method in Tricine-SDS-PAGE, was approximately 1.4 kDa.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.631-636
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• 1999

The thermostable endo-chitosanase gene from the isolated strain Bacillus sp. KFB-C108 was identified on the basis of a phylogenetic analysis of the 16S rRNA gene sequence, and was cloned into plasmid pUCl8 using E. coli $DH5\alpha$ as the host strain. Positive clones carrying recombinant plasmids (pKCHO I and pKCHO II) containing chitosanase activity were selected using the direct activity staining method. Detailed physical maps showed the two plasmid inserts were identical except that the KCHO II insert (2.6 kb) was 1.8 kb smaller than that of the KCHO I. The recombinant plasmids were analyzed to determine the essential region for chitosanase activity, and a 1.3-kb fragment (KCHO-6) was subcloned into pTrc99A using the EcoRI and BamHI sites to construct pTrc99A/KCHO-6(pTrEB13). The resulting plasmid exerted high chitosanase activity upon transformation of E. coli $DH5{\alpha}cells$, overproducing about 20 times more in the cloned cells than in the wild-type cells. The cloned chitosanase protein exhibited the same molecular weight and catalytic activity similar to those of Bacillus sp. KFB-C108. The cloned enzyme was an endo-type that produced a chitosan tetramer as the major reaction product; however, it produced no monomers or dimers.

• Journal of Microbiology and Biotechnology
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• v.17 no.5
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• pp.784-791
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• 2007

The present work aims to use a biofilter technology(aerated submerged filters) for the aerobic transformation at laboratory-scale of olive washing water(OWW) generated in the first steps of olive oil processing, as well as the genetic profiling and identification to the species level of the bacteria involved in the formation of the biofilm, by means of TGGE. Chemical parameters, such as biological oxygen demand at five days($BOD_5$) and chemical oxygen demand(COD), decreased markedly(up to 90 and 85%, respectively) by the biological treatment, and the efficiency of the process was significantly affected by aeration and inlet flow rates. The total polyphenol content of inlet OWW was only moderately reduced(around 50% decrease of the inlet content) after the biofilter treatment, under the conditions tested. Partial 16S rRNA genes were amplified using total DNA extracted from the biofilm and separated by TGGE. Sequences of isolated bands were mostly affiliated to the $\alpha-subclass$ of Proteobacteria, and often branched in the periphery of bacteria] genera commonly present in soil(Rhizobium, Reichenowia, Agrobacterium, and Sphingomonas). The data obtained by the experimentation at laboratory scale provided results that support the suitability of the submerged filter technology for the treatment of olive washing waters with the purpose of its reutilization.

• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1349-1360
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• 2015

The rhizospheric zone abutting plant roots usually clutches a wealth of microbes. In the recent past, enormous genetic resources have been excavated with potential applications in host plant interaction and ancillary aspects. Two Pseudomonas strains were isolated and identified through 16S rRNA and rpoD sequence analyses as P. fluorescens QAU67 and P. putida QAU90. Initial biochemical characterization and their root-colonizing traits indicated their potential role in plant growth promotion. Such aerobic systems, involved in gluconic acid production and phosphate solubilization, essentially require the pyrroloquinoline quinine (PQQ)-dependent glucose dehydrogenase (GDH) in the genome. The PCR screening and amplification of GDH and PQQ and subsequent induction of mutagenesis characterized their possible role as antioxidants as well as in growth promotion, as probed in vitro in lettuce and in vivo in rice, bean, and tomato plants. The results showed significant differences (p ≤ 0.05) in parameters of plant height, fresh weight, and dry weight, etc., deciphering a clear and in fact complementary role of GDH and PQQ in plant growth promotion. Our study not only provides direct evidence of the in vivo role of GDH and PQQ in host plants but also reveals their functional inadequacy in the event of mutation at either of these loci.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.805-814
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• 2008

Liming of acidic soils can prevent aluminum toxicity and improve crop production. Some maize lines show aluminum (Al) tolerance, and exudation of organic acids by roots has been considered to represent an important mechanism involved in the tolerance. However, there is no information about the impact of liming on the structures of bacterial and fungal communities in Cerrado soil, nor if there are differences between the microbial communities from the rhizospheres of Al-tolerant and Al-sensitive maize lines. This study evaluated the effects of liming on the structure of bacterial and fungal communities in bulk soil and rhizospheres of Al-sensitive and Al-tolerant maize (Zea mays L.) lines cultivated in Cerrado soil by PCR-DGGE, 30 and 90 days after sowing. Bacterial fingerprints revealed that the bacterial communities from rhizospheres were more affected by aluminum stress in soil than by the maize line (Al-sensitive or Al-tolerant). Differences in bacterial communities were also observed over time (30 and 90 days after sowing), and these occurred mainly in the Actinobacteria. Conversely, fungal communities from the rhizosphere were weakly affected either by liming or by the rhizosphere, as observed from the DGGE profiles. Furthermore, only a few differences were observed in the DGGE profiles of the fungal populations during plant development when compared with bacterial communities. Cloning and sequencing of 16S rRNA gene fragments obtained from dominant DGGE bands detected in the bacterial profiles of the Cerrado bulk soil revealed that Actinomycetales and Rhizobiales were among the dominant ribotypes.