• Journal of Microbiology and Biotechnology
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• v.7 no.2
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• pp.107-113
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• 1997

A strain producing a high amount of chitinase was isolated from soil, identified as Pseudomonas sp., and tentatively named Pseudomonas sp. YHS-A2. An extracellular chitinase of Pseudomonas sp. YHS-A2 was purified according to the procedure of ammonium sulfate saturation, affinity adsorption, Sephadex G-100 gel filtration and Phenyl-sepharose CL-4B hydrophobic interaction column chromatography. The molecular weight of the purified enzyme was estimated to be 55 kDa on SDS-PAGE was confirmed by active staining. Optimal pH and temperature of the enzyme are pH 7.0 and $50^{\circ}C$, respectively, and the enzyme is stable between pH 5.0 and 8.0 and below $50^{\circ}C$. The main products of colloidal chitin by the chitinase were N-acetyl-D-glucosamine and N,N'-diacetylchitobiose both of which were detected by HPLC analysis. The enzyme is supposed to be a random-type endochitinase which can degrade any position of ${\beta}$-l,4-linkages of chitin and chitooligosaccharides. The chitinase inhibited the growth of some phytopathogenic fungi, Fusarium oxysporum, Botrytis cineria, and Mucor rouxii and these antifungal effects were thought to be due to the characteristics of endochitinase.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.346-356
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• 2011

BACKGROUND: Chemical fungicides not only may pollute the ecosystem but also can be environmentally hazardous, as the chemicals accumulate in soil. Biological control is a frequently-used environment-friendly alternative to chemical pesticides in phytopathogen management. However, the use of microbial products as fungicides has limitations. This study isolated and characterized a three-antifungal-enzyme (chitinase, cellulase, and ${\beta}$-1,3-glucanase)-producing bacterium, and examined the conditions required to optimize the production of the antifungal enzymes. METHOD AND RESULTS: The antifungal enzymes chitinase, cellulase, and ${\beta}$-1,3-glucanase were produced by bacteria isolated from an sawmill in Korea. Based on the 16S ribosomal DNA sequence analysis, the bacterial strain AM50 was identical to Streptomyces sp. And their antifungal activity was optimized when Streptomyces sp. AM50 was grown aerobically in a medium composed of 0.4% chitin, 0.4% starch, 0.2% ammonium sulfate, 0.11% $Na_2HPO_4$, 0.07% $KH_2PO_4$, 0.0001% $MgSO_4$, and 0.0001% $MnSO_4$ at $30^{\circ}C$. A culture broth of Streptomyces sp. AM50 showed antifungal activity towards the hyphae of plant pathogenic fungi, including hyphae swelling and lysis in P. capsici, factors that may contribute to its suppression of plant pathogenic fungi. CONCLUSION(S): This study demonstrated the multiantifungal enzyme production by Streptomyces sp. AM50 for the biological control of major plant pathogens. Further studies will investigate the synergistic effect, to the growth regulations by biogenic amines and antifungal enzyme gene promoter.

• Applied Biological Chemistry
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• v.41 no.7
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• pp.496-499
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• 1998

For the production of theobromine from caffeine, 5 strains of bacteria capable of producing theobromine were isolated from soil. Among them, the strain CT-017 showed the best ability of producing theobromine, and was partially identified as a Pseudomonas sp. For the production of theobromine, fructose was the most effective carbon source at an optimum concentration of 5 g/l. The most effective nitrogen source was 5 g/l of beef extracts. And 0.02 g/l of $Fe^{2+}$, 1.0 g/l of threonine were effective for the production of theobromine. The optimum temperature and initial pH were $28^{\circ}C$ and 6.5, respectively. After 23 hr cultivation, 7.98 g/l of theobromine was produced from 15 g/l of caffeine which corresponds to a conversion yield of 53.2%.

• Applied Biological Chemistry
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• v.49 no.3
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• pp.165-169
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• 2006

A Citrobacter sp. MB 2, azo dyes decolorizing bacterium, was isolated from the wastewater and soil and identified as Citrobacter sp.. It was examined that optimum conditions for culture media were 0.5% of sucrose, 1.0% of yeast extract, 0.1% of $K_2HPO_4$, 0.1% of $NaHCO_3$ per distilled water. The best efficient condition of culture was obtained at pH 7.0, $30^{\circ}C$ and aerobic shaking culture. The number of Citrobacter sp. MB2 in optimum medium was increased more than 7 fold compared to basal medium and 50 fold compared to nutrient broth. This strain was exhibited strong resistance against metal salts and antibiotics (ampicillin and penicillin G).

• Applied Biological Chemistry
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• v.47 no.2
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• pp.164-169
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• 2004

In the course of our screening for biocontrol agent (BCA) against Streptomyces scabiei and S. turgidiscabies causing potato scab using 5,000 actinomtcete isolates, 9 antagonistic strains were selected as BCA candidates through in vitro and in vivo assay. An antagonistic strain, A020645 was highly resistant to some pesticides and antibiotics such as dazomet and mancozeb and showed high control value in vivo. Two bioactive compounds (compound A, B) were purified by anion exchange chromatography, solid phase (ODS) extraction, TLC and reverse phase HPLC. Their chemical structures are now thought to be nucleoside derivative as determined by $^1H-NMR$ data analysis. Their full chemical structures would be elucidated through $^{13}C-NMR$, HMQC and HMBC analyses. Further studies will be focused on fitness in soil and formulation of the BCA candidates.

• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.72-77
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• 2014

It is known that there is no demand for building the arctic environment in Korea. However, it is important to use the different energy source instead of fuel source due to global warming. It is now demanded of using gas of Alaska and Siberia for long term developing the natural gas. The design of gas pipelines in Korea is very different from the arctic region. The operation of gas in arctic region have to consider of arctic region such as permafrost and active regions. It is needed to understand of gas pipeline design with different arctic soil properties. Nowadays, the pipelines is designed with stress-based and but there is demanded for strain based design with more deformed pipeline. We study of arctic environment with different active region using Finite Element Method of thermal elasto-plastic analysis.

• Journal of Species Research
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• v.7 no.3
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• pp.231-239
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• 2018

While screening indigenous prokaryotic species in Republic of Korea in 2017, a total of 17 bacterial strains assigned to the phylum Bacteroidetes were isolated from a variety of environmental habitats including water of fountain, tidal flat, plant root, soil, the gut of Russian grayling butterfly, ginseng field, seawater, lagoon and seashore sand. From the 16S rRNA gene sequence similarity of more than 98.7% and the formation of a robust phylogenetic clade with the closest species, it was found that the 17 strains belong to independent and recognized bacterial species. There has been no official report that the identified 17 species have been previously isolated in the Republic of Korea. Thus, 15 species in 10 genera of one family in the order Flavobacteriales, one species in one genus of one family in the order Cytophagales, and one species in one genus of one family in the order Sphingobacteriales are proposed as unrecorded species of the phylum Bacteroidetes found in the Republic of Korea. Gram reaction, colony and cell morphology, basic phenotypic characteristics, isolation source, taxonomic status, strain ID and other information are described in the species descriptions.

• Journal of Species Research
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• v.9 no.2
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• pp.85-104
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• 2020

In 2019, after a comprehensive investigation of indigenous prokaryotic species in Korea, a total of 12 bacterial strains assigned to the phylum Proteobacteria were isolated from soil. With the high 16S rRNA gene sequence similarity (>98.8%) and formation of a robust phylogenetic clade with the closest species, it was determined that each strain belonged to independent, predefined bacterial species. This study identified two species in the family Burkholderiaceae, one species in the family Comamonadaceae, two species in the family Oxalobacteraceae, one species in the family Micrococcaceae, one species in the family Bradyrhizobiaceae, one species in the family Methylobacteriaceae, one species in the family Rhizobiaceae, one species in the family Rhodocyclaceae, and one species in the family Sphingomonadaceae. There is no official report about these 12 species in Korea, so are described as unreported bacterial species in Korea in this study. Gram reaction, basic biochemical characteristics, colony, and cell morphology are also described in the species description section.

• The Plant Pathology Journal
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• v.26 no.4
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• pp.353-359
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• 2010

In order to control postharvest spoilage of satsuma mandarin fruits, rhizobacteria were isolated from soil samples. The Pantoea agglomerans strain 59-4 (Pa 59-4) which suppresses the decay of mandarin fruit by green and blue mold, was tested for the control efficacy and its mode of action was investigated. Pa 59-4 inhibited infection by green and blue mold on wounded mandarins, which were artificially inoculated with a spore suspension of Penicillium digitatum and P. italicum with control efficacies of 85-90% and 75-80%, respectively. The biocontrol efficacy was increased by raising the concentration of cells to between $10^8$ and $10^9\;cfu/ml$, and pretreatment with the antagonist prevented subsequent infection by green mold. The population of Pa 59-4 was increased more than 10 fold during the 24 hr incubation at $20^{\circ}C$, indicating that colonization of the wound site might prevent the infection by green mold. Despite poor antifungal activity, the Pa 59-4 isolate completely inhibited the germination and growth of P. digitatum spores at $1{\times}10^8\;cfu/ml$. We argue that the control efficacy was mediated by nutrient competition. Overall, the effective rhizobacterium, Pa 59-4, was shown to be a promising biocontrol agent for the postharvest spoilage of mandarin fruits by green and blue mold.

• Korean Journal of Microbiology
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• v.25 no.4
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• pp.346-352
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• 1987

One hundred and seventeen colonies were screened for the detection of the production of exodextranase on the dextran-mineral salts medium. Ten colonies out of them produced the dextranase. Flavobacterium multivorum greatly producing the enzyme was isolated from soil, identified and then studied for various biochemical characteristics. The activity of the dextranase in the cultured medium was high between pH8 and 9 at $35^{\circ}C$, and between $45^{\circ}C$ and $55^{\circ}C$ at pH8. By the growth curves the generation times of the bacterium were approximately 52 minutes in the LB broth, 38 minutes in the LB plus 1% dextran and 660 minutes in the dextran-salts. The strain did not have ant plasmid, and was susceptible to genramicin, cotrimoxazole and cefoperazone, and moderately susceptible to chloramphenicol, cefamandole and cefotaxime, but resistant to ampicillin, cephalothin, tetracycline, amikacin and tobramycin.