• The Plant Pathology Journal
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• v.28 no.1
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• pp.68-74
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• 2012

Biocontrol microbes have mainly been screened among large collections of microorganisms $via.$ nutrient-rich $in$ $vitro$ assays to identify novel and effective isolates. However, thus far, isolates from only a few genera, mainly spore-forming bacilli, have been commercially developed. In order to isolate field-effective biocontrol microbes, we screened for more than 200 oligotrophic bacterial strains, isolated from rhizospheres of various soil samples in Korea, which induced systemic resistance against the soft-rot disease caused by $Pectobacterium$ $carotovorum$ SCC1; we subsequently conducted in $planta$ bioassay screening. Two oligotrophic bacterial strains were selected for induced systemic disease resistance against the $Tobacco$ $Mosaic$ $Virus$ and the gray mold disease caused by $Botrytis$ $cinerea$. The oligotrophic bacterial strains were identified as $Pseudomonas$ $manteilii$ B001 and $Bacillus$ $cereus$ C003 by biochemical analysis and the phylogenetic analysis of the 16S rRNA sequence. These bacterial strains did not exhibit any antifungal activities against plant pathogenic fungi but evidenced several other beneficial biocontrol traits, including phosphate solubilization and gelatin utilization. Collectively, our results indicate that the isolated oligotrophic bacterial strains possessing induced systemic disease resistance could provide useful tools as effective biopesticides and might be successfully used as cost-effective and preventive biocontrol agents in the field.

• Journal of Species Research
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• v.4 no.2
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• pp.109-126
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• 2015

As a subset study to discover indigenous prokaryotic species in Korea, a total of 39 bacterial strains assigned to the classes Betaproteobacteria and Gammaproteobacteria were isolated from diverse environmental samples collected from soil, tidal flat, freshwater, seawater, seaweed, wetland, plant roots, guts of insects, and fermented foods. From the high 16S rRNA gene sequence similarity (>99.1%) 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 39 species have been described in Korea; therefore 4 species of 4 genera in the order Burkholderiales and 1 species in the order Neisseriales within the class Betaproteobacteria, and 10 species of 6 genera in the order Alteromonadales, 11 species of 3 genera in the order Pseudomonadales, 4 species of 4 genera in the order Enterobacteriales, 2 species of 2 genera in the order Vibrionales, 1 species in the order Aeromonadales, 3 species of 3 genera in the order Oceanospirillales, 2 species of 2 genera in the order Xanthomonadales, and 1 species in the order Chromatiales within the Gammaproteobacteia are reported for proteobacterial 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.

• Journal of Species Research
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• v.7 no.2
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• pp.161-180
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• 2018

Fourteen bacterial strains, low10-4-1, J11015, 17J27-22, 17G22-9, 17G9-4, 17Bio_15, 17gy_33, 17SD1_21, Strain8, 17Sr1_17, J21014T, H31021, 17J49-9, and 17J80-6 assigned to the phylum Actinobacteria, Bacteroidetes, Deinococcus-Thermus, and Firmicutes were isolated from soil samples. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strains low10-4-1, J11015, 17J27-22, 17G22-9, 17G9-4, 17Bio_15, 17gy_33, 17SD1_21, Strain8, 17Sr1_17, J21014T, H31021, 17J49-9, and 17J80-6 were most closely related to Marmoricola aurantiacus (98.9%), Calidifontibacter indicus (99.8%), Gordonia soli (98.8%), Rhodococcus globerulus (99.5%), Pseudarthrobacter siccitolerans (99.1%), Hymenobacter qilianensis (98.7%), Hymenobacter terrae (99.0%), Deinococcus yunweiensis (99.2%), Deinococcus proteolyticus (99.7%), Domibacillus indicus (99.2%), Exiguobacterium mexicanum (100.0%), Kurthia senegalensis (99.1%), Lysinibacillus composti (99.6%), and Bacillus loiseleuriae (99.3%). These fourteen species have never been reported in Korea, therefore we report them here for the first time.

• Journal of Species Research
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• v.7 no.2
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• pp.135-150
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• 2018

Eleven bacterial strains 17SD2_15, 17Sr1_23, 17SD2_13, 17Sr1_31, 17gy_18, 16B15D, 16B02D, 16B04G, 16B01D, 17U4-2 and 17J28-10 assigned to the phylum Proteobacteria were isolated from soil samples collected from Seoul Women's University, in South Korea. The Belnapia species, strain 17SD2_15 was cocci-shaped and pink-colored. The Methylobacterium species, strain 17Sr1_23, 17SD2_13, 17Sr1_31, and 16B15D were short rod-shaped and pink-colored. The Microvirga species, strain 17gy_18, and 16B02D were short rod-shaped and pink-colored. The Oxalicibacterium species, strain 16B04G was short rod-shaped and pink-colored. The Sphingomonas species, strain 16B01D was short rod-shaped and yellow-colored. The Variovorax species, strain 17U4-2 was cocci-shaped and yellow-colored. The Paracoccus species, 17J28-10 was cocci-shaped and orange-colored. Phylogenetic analysis based on 16S rRNA gene sequence showed that strains 17SD2_15, 17Sr1_23, 17SD2_13, 17Sr1_31, 17gy_18, 16B15D, 16B02D, 16B04G, 16B01D, 17U4-2 and 17J28-10 were most closely related to Belnapia soli (with 99.9% similarity), Methylobacterium gregans (99.1%), Methylobacterium isbiliense (99.6%), Methylobacterium oxalidis (99.9%), Microvirga aerilata (98.7%), Methylobacterium aerolatum (99.0%), Microvirga vignae (100.0%), Noviherbaspirillum canariense (100.0%), Sphingomonas desiccabilis (100.0%), Variovorax humicola (99.6%), and Paracoccus acridae (99.1%), respectively. This is the first report of these eleven species in Korea.

• Journal of Species Research
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• v.7 no.1
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• pp.36-49
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• 2018

During a study to discover indigenous prokaryotic species in Korea in 2016, a total of 42 actinobacterial isolates were recovered from various environmental samples collected from natural cave, squid, sewage, sea water, trees, droppings of birds, freshwater, eelgrass, mud flat, sediment and soil. On the basis of a tight phylogenetic clade with the closest species and high level of 16S rRNA gene sequence similarity, it was shown that each isolate was assigned to independent and previously described bacterial species which were assigned to the phylum Actinobacteria. The following 42 species have not been reported in Korea: eight species in two genera n the order Corynebacteriales, 26 species of 16 genera in the Micrococcales, one species of one genus in the Micromonosporales, one species of one genus in the Propionibacteriales, four species of two genera in the Streptomycetales and two species of two genera in the Streptosporangiale. Cell morphology, Gram staining reaction, colony colors and features, the media and conditions of incubation, physiological and biochemical characteristics, origins of isolation and strain IDs of 42 unrecorded actinobacterial species are presented in the species description.

• Journal of Species Research
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• v.7 no.1
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• pp.50-59
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• 2018

During the course of investigation of indigenous prokaryotic species in Korea, a total of 30 bacterial strains belonging to the phylum Firmicutes were isolated from diverse environmental sites such as soil, avian feces, wastewater treatment plants, fermented vegetables, seawater, algae, sea cucumber, octopus and tidal flat sediment. Phylogenetic analysis based on 16S rRNA gene sequences revealed that each strain showed high sequence similarity (${\geq}98.7%$) to the closest type strain and formed a robust phylogenetic clade with the most closely related species in the phylum Firmicutes. To date, there is no official record of these 30 species in Korea. Therefore, we report 26 species of 12 genera in the order Bacillales and 4 species of 4 genera in the order Lactobacillales which have not been reported in Korea. Morphological and biochemical characteristics, isolation sources and NIBR deposit numbers are described in the species descriptions.

• KSBB Journal
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• v.31 no.3
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• pp.158-164
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• 2016

Plant growth promoting (PGP) hormones, which are produced in a small quantity by bacteria, affect in plant growth and development. PGPs play an important role on the crop productivity in agricultural field. In this study, a photosynthetic bacterial strain producing the PGP was isolated from paddy soil. Bacterial isolate was gram negative, rod-shaped and motility positive. From the 16s rRNA gene sequence analysis, the isolate was identified as Rhodobacter capsulatus PS-2. The mass cultivation of R. capsulatus PS-2 was optimized by considering of the carbon, nitrogen and inorganic salt sources. Optimal medium composition was determined as Na-succinate 4.5 g, yeast extract 5 g, $K_2HPO_4$ 1 g, $MgSO_4$ 5 g, per liter. From the result of 500 L fermentation for 2 days using the optimal medium, the viable cells were $8.7{\times}10^9cfu/mL$. R. capsulatus PS-2 strain produced the carotenoid and indole-3-acetic acid (IAA). The carotenoid extraction and quantitative analysis were performed by HCl-assisting method. Total carotenoid contents from R. capsulatus PS-2 culture broth were measured as $7.02{\pm}0.04$ and $6.93{\pm}0.05mg/L$ under photoheterotrophic and chemoheterotrophic conditions, respectively. To measure the productivity of IAA, colorimetric method was employed using Salkowski reagent at optical density 535 nm. The results showed that the highest content of IAA was $197.44{\pm}5.92mg/L$ in the optimal medium supplemented with 0.3% tryptophan.

• Magazine of the Korea Concrete Institute
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• v.11 no.1
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• pp.231-242
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• 1999

This paper presents a numerical study on the flat plates in deep basements, subjected to out-of-plane floor load and in-plane compressive load due to soil and hydraulic lateral pressure. For nonlinear finite element analysis, a computer program addressing material and geometric nonlinearities is developed. The validity of the numerical model is established by comparison with existing experiments performed on plates simply supported on four edges. The flat plates to be studied are designed according to the Direct Design Method in Korean Building Code for Structural Concrete. Through numerical study on the effects of different load combinations and loading sequence, the load condition that governs the strength of the flat plates is determined. For the plates under the governing load condition, parametric studies are performed to investigate variations of the strength with reinforcement ratio, aspect ratio, concrete strength, and slenderness ratio. Based on the numerical results, the floor load magnification factor is proposed.

• Journal of Microbiology and Biotechnology
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• v.12 no.5
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• pp.729-734
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• 2002

Radiorespirometric analysis revealed that Pseudomonas sp. strain KKI isolated from a soil contaminated with petroleum hydrocarbons was able to catabolize polycyclic aromatic hydrocarbons such as phenanthrene and naphthalene. The rate and extent of phenanthrene mineralization was markedly enhanced when the cells were pregrown on either naphthalene or phenanthrene, compared to the cells grown on universal carbon sources (i.e., TSA medium). Deduced amino acid sequence of the Rieske-type iron-sulfur center of a putative phenanthrene dioxygenase (PhnAl) obtained from the strain KKI shared significant homology with DxnAl (dioxin dioxygenase) from Spingomonas sp. RW1, BphA1b (biphenyl dioxygenase) from Spingomonas aromaticivorans F199, and PhnAc (phenanthrene diokygenase) from Burkholderia sp. RP007 or Alcaligenes faecalis AFK2. Northern hybridization using the dioxygenase gene fragment cloned from KKI showed that the expression of the putative phn dioxygenase gene reached the highest level in cells grown in the minimal medium containing phenanthrene and $KNO_3$, and the expression of the phn gene was repressed in cells grown with glucose. In addition to the metabolic change, phospholipid ester-linked fatty acids (PLFA) analysis revealed that the total cellular fatty acid composition of KKI was significantly changed in response to phenanthrene. Fatty acids such as 14:0, 16:0 3OH, 17:0 cyclo, 18:1$\omega$7c, 19:0 cyclo increased in phenanthrene-exposed cells, while fatty acids such as 10:0 3OH, 12:0, 12:0 2OH, 12:0 3OH, 16:1$\omega$7c, 15:0 iso 2OH, 16:0, 18:1$\omega$6c, 18:0 decreased.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1498-1503
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• 2007

To identify novel crystal proteins, Bacillus thuringiensis 2385-1 was isolated from Korean soil samples and characterized. The H-serotype of 2385-1 was identical to that of subsp. kenyae (H4a4c), and its crystal toxin was bipyramidal-shaped. However, 2385-1 showed a much higher toxicity towards Plutella xylostella and Spodoptera exigua larvae than subsp. kenyae. In addition, the crystal protein profile and plasmid DNA pattern of 2385-1 differed from those of subsp. kenyae. To verify the crystal protein gene types of 2385-1, a PCR-RFLP analysis was performed, and the results revealed that 2385-1 contained two novel cry1-type crystal protein genes, cryl-5 and cry1-12, in addition to the crylJal gene. The deduced amino acid sequences of cryl-5 and cry1-12 showed a 97.9% and 75.7% sequence similarity with the CrylAb and CrylJa crystal proteins, respectively. Among the novel crystal proteins, Cry1-5 showed a high toxicity towards P. xylostella and S. exigua larvae. In conclusion, B. thuringiensis 2385-1 is a new isolate in terms of its gene types, and should be a promising source for an insecticide to control lepidopteran larvae.