• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.1
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• pp.31-40
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• 1999

This study was conducted to investigate the effects of rhizosphere bacterium and pathogenic fungi on the growth of corn(Zea may L.) in continuous corn cultivation soil(CCCS) and non-continuous cultivation soil(NCCS). Corn was established by seeding into pots of 30 cm in diameter and 50 cm in depth containing 1 : 1 mixture of soil and vermiculite. Rhizobacterium and pathogenic fungi were inoculated into the soils. The field experiment was carried out at the Animal Research Station, College of Agriculture, Chonnam National University. Sample of corn was taken from each pot at 50 days and 90 days after sowing. Corn was cultivated in a vinyl house with three replications under natural daylight conditions. The bacterium used in this study was Bacillus subtilis. B. subtilis was directly isolated and identified from forage rhizosphere soil. Dry matter(DM) of coron plant in treatment without B. subtilis was lower than that in treatment of B. subtilis. DM of corn plant inoculated with B. subtilis was higher than that of corn inoculated with pathogenic fungi in both CCCS and NCCS. DM of corn plant in NCCS was more increased than that in CCCS. The effect of B. subtilis inoculation on the growth of corn was better in NCCS than in CCCS. However, DM of corn plant was apparently decreased by the inoculation of the pathogenic fungi in both CCCS and NCCS.

• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.70-77
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• 2007

Pseudomonas sp. KM1 was separated from soil contaminated by petroleum and identified. The isolated strain is Gram-positive, rod-shaped and immotile. In batch culture, the optimum cultivation temperature and pH was $35^{\circ}C$ and 7, respectively. Biodegradation of PAHs experiment with soil slurry system was performed using Pseudomonas sp. KM1. Pseudomonas sp. KM1 could degrade 7 PAHs including naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, pyrene, and fluoranthene. These mixed PAHs was easily degraded within one day except fluoranthene, which was degraded much slowly, taking several days by this isolated bacteria. Pseudomonas sp. KM1 is good candidate for bioremediation of PAHs contaminated soils. Biodegradation rates of naphthalene, phenanthrene and pyrene in soils were different at each soil, and the rates were decreased as sorption capacity increased.

• Microbiology and Biotechnology Letters
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• v.51 no.2
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• pp.203-207
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• 2023

The N₂O-reducing rhizobacterium, Pseudomonas sp. M23, was isolated from maize rhizosphere soil. The maximum N₂O reduction rate of the strain M23 was 15.6 mmol·g-dry cell weight^-1·h^-1. Its N₂O reduction activity was not inhibited by diesel contaminant, and it was enhanced by the addition of the root exudates of maize and tall fescue. The remediation efficiency of diesel-contaminated soil planted with maize or tall fescue was not inhibited by inoculating with the strain M23. Root weights in the soil inoculated with the strain M23 were greater than those in the non-inoculated soil. These results suggest that Pseudomonas sp. M23 is a promising bacterium to mitigate N₂O emissions during the remediation of diesel-contaminated soil.

• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.220-230
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• 2014

BACKGROUND: Excessive metals in the soil have become one of the most significant environmental problems. Phytoremediation has received considerable attention as a method for restoring the contaminated soils. The microbes having remarkable metal tolerance and plant growth-promoting abilities could also play a significant role in remediation of metal-contaminated soils, because bioaugmentation with such microbes could promote phytoextraction of metals. Therefore, the present study was focused on evaluating the phytoextraction of heavy metals (Co, Pb and Zn) in Helianthus annuus (sunflower) induced by bioaugmentation of a phosphate solubilizing bacterium. METHODS AND RESULTS: A phosphate solubilizing bacterium was isolated from metal-contaminated soils based on the greater halo size (>3 mm) with solid NBRIP agar medium containing 10 g glucose, 5 g $Ca_3(PO_4)_2$, 5 g $MgCl_2{\cdot}6H_2O$, 0.25 g $MgSO_4.7H_2O$, 0.2 g KCl, 0.1 g $(NH_4)_2SO_4$ in 1 L distilled water. Isolated bacterial strain was assessed for their resistance to heavy metals; $CoCl_2.6H_2O$, $2PbCO_3.Pb(OH)_2$, and $ZnCl_2$ at various concentrations ranging from $100-400{\mu}g/mL$ (Co, Pb and Zn) using the agar dilution method. A pot experiment was conducted with aqueous solutions of different heavy metals (Co, Pb and Zn) to assess the effect of bacterial strain on growth and metal uptake by Helianthus annuus (sunflower). The impact of bacterial inoculation on the mobility of metals in soil was investigated under laboratory conditions with 50 mL scaled polypropylene centrifuge tubes. The metal contents in the filtrate of plant extracts were determined using an atomic absorption spectrophotometer (Perkinelmer, Aanalyst 800, USA). CONCLUSION: Inoculation with Enterobacter ludwigii PSB 28 resulted in increased shoot and root biomass and enhanced accumulation of Co, Pb and Zn in Helianthus annuus plants. The strain was found to be capable of promoting metal translocation from the roots to the shoots of H. annuus. Therefore, Enterobacter ludwigii PSB 28 could be identified as an effective promoter of phytoextraction of Co, Pb and Zn from metal-contaminated soils.

• Microbiology and Biotechnology Letters
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• v.45 no.1
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• pp.43-50
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• 2017

A xylan-degrading bacterium (strain WJ-1) was isolated from soil collected from Jeju Island, Republic of Korea. Strain WJ-1 was characterized as a gram-positive, aerobic, and spore-forming bacterium. The predominant fatty acid in this bacterium was anteiso-$C_{15:0}$ (42.99%). A similarity search based on 16S rRNA gene sequences suggested that the strain belonged to the genus Streptomyces. Further, strain WJ-1 shared the highest sequence similarity with the type strains Streptomyces spinoveruucosus NBRC 14228, S. minutiscleroticus NBRC 13000, and S. glaucescens NBRC 12774. Together, they formed a coherent cluster in a phylogenetic tree based on the neighbor-joining algorithm. The DNA G+C content of strain WJ-1 was 74.7 mol%. The level of DNA-DNA relatedness between strain WJ-1 and the closest related species S. glaucescens NBRC 12774 was 85.7%. DNA-DNA hybridization, 16S rRNA gene sequence similarity, and the phenotypic and chemotaxonomic characteristics suggest that strain WJ-1 constitutes a novel subspecies of S. glaucescens. Thus, the strain was designated as S. glaucescens subsp. WJ-1 (Korean Agricultural Culture Collection [KACC] accession number 92086). Additionally, strain WJ-1 secreted thermostable endo-type xylanases that converted xylan to xylooligosaccharides such as xylotriose and xylotetraose. The enzymes exhibited optimal activity at pH 7.0 and $55^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.35 no.2
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• pp.150-157
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• 2007

The advanced bioremediation of diesel-contaminated soil through the exploration of bacterial interaction with plants was studied. A diesel-degrading rhizobacterium, Rhodococcus sp.412, and a plant species, Zea mays, having tolerant against diesel was selected. Zea mays was seeded in uncontaminated soil or diesel-contaminated soil with or without Rhodococcus sp. 412. After cultivating for 30 days, the growth of Zea mays in the contaminated soil inoculated with Rhodococcus sp. 412 was better than that in the contaminated soil without the bacterium. The residual diesel concentrations were lowered by seeding Zea mays or inoculating Rhodococctis sp. 412. These results Indicate that the simultaneous use of Zea mays and Rhodococcus sp. 412 can give beneficial effect to the remediation of oil-contaminated soil. Bacterial community was characterized using a 16S rDNA PCR and denaturing gradient gel electrophoresis (DGGE) fingerprinting method. The similarities of DGGE fingerprints were $20.8{\sim}39.9%$ between the uncontaminated soil and diesel contaminated soil. The similarities of DGGE fingerprints were $21.9%{\sim}53.6%$ between the uncontaminated soil samples, and $31.6%{\sim}50.0%$ between the diesel-contaminated soil samples. This results indicated that the structure of bacterial community was significantly influence by diesel contamination.

• Korean Journal of Microbiology
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• v.49 no.1
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• pp.83-89
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• 2013

A bacterium, isolated from a vegetable field in a plastic film house and named strain CY6 was capable of biodegrading chlorpyrifos (CP). Based on the phenotypic features and the phylogenetic similarity of 16S rRNA gene sequences, strain CY6 was identified as a Naxibacter sp.. CP was utilized as the sole source of carbon and phosphorus by Naxibacter sp. CY6. We examined the role of this Naxibacter sp. in the degradation of other OP insecticides under liquid cultures. Parathion, methyl parathion, diazinon, cadusafos, and ethoprop could also be degraded by Naxibacter sp. CY6 when they are provided as the sole sources of carbon and phosphorus. Additionally, Naxibacter sp. CY6 ($10^8$ CFU/g) added to soil with CP (100 mg/kg) resulted in a higher degradation rate of approximately 90% than the rate obtained from uninoculated soils. These results highlight the potential of this bacterium to be used in the cleanup of contaminated pesticide soil.

• KSBB Journal
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• v.27 no.2
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• pp.75-85
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• 2012

Although, microbial arsenic mobilization by dissimilatory arsenate-reducing bacteria (DARB) and the practical use to the removal technology of arsenic from contaminated soil are expected, most previous research mainly has been focused on the geochemical circulation of arsenic. Therefore, in this review we summarized the previously reported DARB to grasp the characteristic for bioremediation of arsenic. Evidence of microbial growth on arsenate is presented based on isolate analyses, after which a summary of the physiology of the following arsenate-respiring bacteria is provided: Chrysiogenes arsenatis strain BAL-$1^T$, Sulfurospirillum barnesii, Desulfotomaculum strain Ben-RB, Desulfotomaculum auripigmentum strains OREX-4, GFAJ-1, Bacillus sp., Desulfitobacterium hafniense DCB-$2^T$, strain SES-3, Citrobacter sp. (TSA-1 and NC-1), Sulfurospirillum arsenophilum sp. nov., Shewanella sp., Chrysiogenes arsenatis BAL-$1^T$, Deferribacter desulfuricans. Among the DARB, Citrobacter sp. NC-1 is superior to other dissimilatory arsenate-reducing bacteria with respect to arsenate reduction, particularly at high concentrations as high as 60 mM. A gram-negative anaerobic bacterium, Citrobacter sp. NC-1, which was isolated from arsenic contaminated soil, can grow on glucose as an electron donor and arsenate as an electron acceptor. Strain NC-1 rapidly reduced arsenate at 5 mM to arsenite with concomitant cell growth, indicating that arsenate can act as the terminal electron acceptor for anaerobic respiration (dissimilatory arsenate reduction). To characterize the reductase systems in strain NC-1, arsenate and nitrate reduction activities were investigated with washed-cell suspensions and crude cell extracts from cells grown on arsenate or nitrate. These reductase activities were induced individually by the two electron acceptors. Tungstate, which is a typical inhibitory antagonist of molybdenum containing dissimilatory reductases, strongly inhibited the reduction of arsenate and nitrate in anaerobic growth cultures. These results suggest that strain NC-1 catalyzes the reduction of arsenate and nitrate by distinct terminal reductases containing a molybdenum cofactor. This may be advantageous during bioremediation processes where both contaminants are present. Moreover, a brief explanation of arsenic extraction from a model soil artificially contaminated with As (V) using a novel DARB (Citrobacter sp. NC-1) is given in this article. We conclude with a discussion of the importance of microbial arsenate reduction in the environment. The successful application and use of DARB should facilitate the effective bioremediation of arsenic contaminated sites.

• Korean Journal of Environmental Biology
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• v.25 no.3
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• pp.267-272
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• 2007

Microorganisms capable of degrading poly(butylene succinate-co-butylene adipate) (PBSA) were isolated from 40 soil samples such as landfill site soil, cultivating soil and activated sludge soil from 20 different sites in Korea by using the enrichment culture and the clear zone test at $37^{\circ}C$. Based on the 16S rDNA sequences, the isolated bacterium was identified to be Streptomyces sp. PBSA-1. Morphological and cultural characteristics were employed for the identification of the isolated fungi and they were proved to be Aspergillus fumigatus PBSA-2 and Aspergillus fumigatus PBSA-3. The PBSA degradation activity of the isolated microorganisms was enhanced through the serial acclimation in PBSA plate medium. The PBSA degrading microorganisms appeared to be highly active for the PBSA degradation in that 83% of PBSA was degraded by Streptomyces sp. PBSA-l, and 65% and 75% of PBSA was mineralized by A. fumigatus PBSA2 and A. fumigatus PBSA-3 respectively during 40 days of the modified Sturm test.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.203-208
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• 2002

미생물 생산은 다양한 산업에 이용되는 핵심산업이다. 그러나 미생물을 장기간 보존하거나 생산 후 현장처리에 상황에 있어 미생물의 활성이 환경 및 각종조건에 따라 장기간 유지되지 못하는 경향이 있다. 따라서, 본 실험에서는 Pseudomonas putida SSEoX의 생산 후 시중에서 판매되는 perlite, diatomite, bentonite, zeolite, dolomite, vermicullite 등의 담체를 이용하여 미생물의 생리활성유지를 위한 실험을 자연현상에서 나타날 수 있는 다양한 온도에서 담체의 종류별로 수행하였다. 그 결과 bentonite를 이용한 담체의 경우 5, 20, 3$0^{\circ}C$에서 40일간 미생물의 밀도가 거의 감소하지 않은 결과로 나타났고 zeolite의 경우 20일 이내의 저온에서 생존율이 높은 것으로 나타났으나 온도의 상승으로 생존율이 현저히 떨어졌다. 또한 Dololite의 경우 초기 20일 내에서는 20t에서 생존율이 매우 높았으나 40일 후 생존율이 현저히 감소하였다. 또한 bentonite의 경우 전체적으로 생존율이 거의 감소되지 않았으며 그중 5$^{\circ}C$와 2$0^{\circ}C$에서 생존율이 가장 높았고 3$0^{\circ}C$에서 30일 후까지는 비교적 적은 감소를 보였으며 40일 이후 비교적 큰 감소율이 있었다. 따라서, 본 실험결과 비교적 낮은 온도에서 bentonite와 vermiculite를 혼합한 담체를 이용한 미생물보존이 가장 우수만 생존유지법이었다.