• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.946-951
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• 2005

Biodegradation of the endocrine-disrupting chemical di-n-butyl phthalate (DBP) was investigated using a bacterium, Pseudomonas fluorescens B-1, isolated from mangrove sediment. The effects of temperature, pH, salinity, and oxygen availability on DBP degradation were studied. Degradation of DBP was monitored by solid-phase extraction using reversed-phase HPLC and UV detection. The major metabolites of DBP degradation were identified as mono-n-butyl phthalate and phthalic acid by gas chromatography-mass spectrometry (GC-MS) and a pathway of degradation was proposed. Degradation by P. fluorescens B-1 conformed to first-order kinetics. Degradation of DBP was also tested in seawater by inoculating P. fluorescens B-1, and complete degradation of an initial concentration of $100{\mu}g/l$ was achieved in 144 h. These results suggest that DBP is readily degraded by bacteria in natural environments.

• Korean Journal Plant Pathology
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• v.14 no.1
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• pp.13-18
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• 1998

The use of bioluminescence as a sensitive marker for the detection of Pseudomnas sp. in the rhizosphere was investigated. Transposon Tn4431 which contains a promoterless luciferase operon and tetracycline resistant gene was used. This transposon, present on a suicide vector (pUCD623) in E. coli HB101, was mated with spontaneous rifampicin mutant of Pseudomonas fluorescens B16, a plant growth promoting rhizobacteria (PGPR), and then rifampicin and tetracycline resistant survivors were isolated. Twenty tow mutants wer isolated from the conjugants between E. coli HB101 and P. fluorescens B16. One of these, B16::Tn4431 (L22) recombinant which glowed brightly in the dark was selected for analysis. The cucumber seeds inoculated with L22 were grown in moisten two layers of filter paper and nonsterile soil contained in half cut PVC pipe. The roots were removed from the filter paper and PVC pipe, then placed on the 1/2 LB media plates. The plates were incubated at room temperature for 16 hr. L22 could successfully be detected in the rhizoplane by using the ordinary negative camera film (ASA100-400) with 30 minutes exposure under dark condition. The root colonizing ability and the plant growth promoting effect of L22 were not reduced compared to the untreated bacteria and wild type. L22 was superior to will type.

• Korean Journal of Environmental Agriculture
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• v.20 no.1
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• pp.50-56
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• 2001

Thirty-three bacterial and fungal strains were isolated from the rotten soybeans and soybean sprouts to isolate pathogenic microorganisms which cause soybean sprouts rot during soybean sprouts cultivation. In pathogenicity tests of the isolates on soybean sprouts, two isolates(K-17 and K-28) caused soybean sprouts rot and were identified as Erwinia carotovora and Fusarium sp., respectively. To isolate antagonists aganist K-17 and K-28 pathogens, bacteria were isolated from various soybean-cultivated soils and screened by the inhibition zone method. A bacterial isolate(J-232) which inhibited growth of both pathogens was identified as Pseudomonas fluorescens and further examined. The culture filtrate of P. fluorescens J-232 (dilution rate of 500 times) inhibited the growth of Erwinia carotovora K-17 and Fusarium sp. K-28 both on potato dextrose agar medium and on soybean sprouts cultivated in vessel. The development of soybean sprouts rots was observed during cultivation by inoculation of soybean seeds with culture filtrate of both pathogens. The combined inoculation of soybean seeds with culture filtrate of antagonistic bacterium and that of pathogens prevented soybean sprouts rot, and the growth of soybean sprouts was similar to that of control. The soybean sprouts inoculated with antagonists culture filtrate alone did not develop soybean sprouts rot, and the growth of the seedlings was shown to be slightly promoted as compared with that of control.

• Korean Journal of Agricultural Science
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• v.40 no.1
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• pp.27-34
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• 2013

To investigate the distribution of psychrotrophic bacteria, raw milk was collected from farms in nine different regions located around Kyunggi province in South Korea at four different seasons. Psychrotrophic counts were higher in winter than in other seasons as $3.0{\times}10^4$ CFU/mL (p<0.05). Among nine regions, the population in raw milk sampled from B region was in significantly greater numbers and those from C and D province were in significantly lower numbers than any other regions, $2.4{\times}10^5$ CFU/mL and $8.7{\times}10^3$ CFU/mL, respectively (p<0.05). In addition, among 706 bacterial isolates, the predominant class was Gamma-proteobacteria (81.02%) and genus was Pseudomonas (32.34%), especially Pseudomonas fluorescens (39.46%). Compared to the regional predominance, Acinetobacter johnsonii in A region, Pseudomonas fluorescens in B region, Enterobacter amnigenus in C region, Psychrobacter maritimus in D region, Acinetobacter johnsonii in E region, Acinetobacter haemolyticus in F region, Pseudomonas fluorescens in G region, Acinetobacter jounsonii in H region, and Pseudomonas mucidolens in I region were found.

• The Korean Journal of Mycology
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• v.20 no.2
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• pp.109-117
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• 1992

Chemotactic responses of five motile saprophytic and one phytopathogenic bacteria e.g. Agrobacterium radiobacter, Bacillus subtilis, B. polymyxa, Pseudomonas aeruginosa, P. fluorescens and Xanthomonas malvacearum towards exudate of Cochliobolus sativus conidia, Fusarium of oxysporum f. sp. ciceri chlamydospores, Macrophomina phaseolina sclerotia and Phytophthora drechsleri f. sp. cajani oospores were determined in vitro at different abiotic conditions. In general, a positive correlation (r=0.76 to 0.89; P=0.05) was observed between concentration of fungal exudates and attraction of bacterial cells. Similarly, a significant (P=0.05; r=+0.82 to 0.95) positive correlation was noticed between chemotactic response and incubation period. The chemotactic response of bacteria was greatly influenced by temperature and pH of the test fungal exudate. The optimum temperature for maximum chemotaxis was $25^{\circ}C$ for A. radiobacter, $30^{\circ}C$ for B. polymyxa, P. aerugionosa, P. fluorescens and X. malvacearum and $35^{\circ}C$ for B. subtilis. Fungal exudates maintained at pH 7 attracted maximum number of bacteria. The response of bacterial cells to exudates at pH 3 and 11 was not significantly (P=0.05) different than that to the buffer (control). Chemotaxis of bacteria was observed towards attractants (fungal propagules and their exudates) when they were kept apart and bridged with the capillaries filled with non-attractant (buffer) or attractant (exudate).

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.445-448
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• 2002

The Pseudomonas fluorescens KCTC 1767, a selected and identified as potential candidate for stereo-specific resolution of rac-ketoprofen ethyl ester, was systematically investigated in order to induce the high level expression and detailed characterization of the expressing enzyme esterase. We cloned the esterase gene from chromosomal DNA of Pseudomonas fluorescens KCTC 1767 by PCR with two synthetic primers that desinged for simple purification. The recombinant esterase from Pseudomonas fluorescens KCTC 1767 exibited a high conversion rate and enantioselectivity to the (S)-ketoprofen ethyl ester as expected. The enzyme was easily purified to homogeniety by using a metal chelating affinity chromatography as a protein with poly histidine taq, and thus obtained 0.6 mg of protein from a 100 mL culture broth in a single step. The purified enzyme was steadily stable at the pH range from 7.0 to 10. The activity was also retained to be about 70% after the preincubation at $40^{\circ}C$ but over $50^{\circ}C$ lost the activity completely. The molecular mass of the esterase was estimated to be about 43 kDa on SDS-PAGE, and an identical result was also shown in gel filteration chromatography. The specific activity was calculated 27 mM/mg-protein/min by using the rac-ketoprofen ethly ester as a substrate.

• The Korean Journal of Food And Nutrition
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• v.9 no.3
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• pp.275-280
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• 1996

For the selection of powerful antagonistic bacterium for biological control of Ewinia sp. causing vegetable soft rot, two excellent strains (54, 565) were selected from 1, 196 strains of bacteria which were isolated from rhizospere in vegetable root rot suppressive soil. Selected 2 strains were identified to be a species to Pseudomonas fluorescens S4 and pseudomonas fluorescens S65 (PS65). The highest of inhibitory activity was produced in 523 synthetic broth medium at pH 7.0 and 25t during 3 ethyl-Al-folpet, and the antibiotics such as vancomycin, perucillin and lincomycin, only PS4 was resistant to erythromycin.

• Journal of Microbiology
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• v.39 no.4
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• pp.338-342
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• 2001

Pseudomonas fluorescens SM11 is a naphthalene-degrading strain whose dissimilatory genes are cho-mosomally encoded. We have cloned the 2.9 kb Sal I fragment harboring genes for the naphthalene-degrading upper pathway. The nucleotide sequences were determined to be nahQ, napA, and partial regions of nahE genes. The nahQ encods a protein of 188 amino acid residues with a deduced molec-ular wight of 20.8kDa. The high homology with other proteins suggests that NAhQ may be an active and useful protein whtich gives as selective advantage to naphthalene degradatin. Transposase(TnpA)encodes a polypetide chain with a molecular mass of 41.8kDa consisting of 376 amino acid residues. The deduced anino acid sequence of tnpA revealed 96% idenitity with putative transposase of P. stutzeri OX1,. It was assumed that transposase plays an important role in the evloution of the catabloic-path way in the regulation of nah expression.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.4
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• pp.275-282
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• 2000

Among the fluorescent pseudomonad isolates from soil- root system of red pepper in Chinju, Kyunsangnam-Do, the phylogenetic analysis for 35 isolates were conducted. The partial 16S ribosomal DNA sequences were used as taxonomic key for phylogenetic analyses, and these sequences were enabled to identification of the fluorescent pseudomonad isolates on the species level. The 17 isolates among them were classified into Pseudomonas putida group, and consisted of the strains isolated mainly from soil. This group were subdivided into 4 subgroups (I, II, III, and IV). The subgroup I and IV were unique ones which were relatively remotely related with subgroup II and III including the type strain of P. putida. The 15 isolates among 35 isolates were grouped along with the type strain of Pseudomonas fluorescens, and 3 isolate were characterized as intermediates of P. fluorescens and Pseudomonas chlororaphis. Most of strain isolateds from the rhizosphere soil and rhizoplane of red pepper were identified as P. fluorescens and closely related with each other. In this study, root of red pepper was supposed to be colonized by a specific strain or strains of P. fluorescens.

• Microbiology and Biotechnology Letters
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• v.48 no.2
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• pp.223-229
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• 2020

The application of plant-growth-promoting rhizobacteria (PGPR) supports the growth of plants in contaminated soil while ureolytic bacteria can immobilise heavy metals by carbonate precipitation. Thus, dual treatment with such bacteria may be beneficial for plant growth and bioremediation in contaminated soil. This study aimed to determine whether the PGPR Pseudomonas fluorescens could work in synergy with ureolytic bacteria to assist with the remediation of cadmium (Cd)- and lead (Pb)-contaminated soils. Pot experiments were conducted to grow radish plants in Cd- and Pb-contaminated soils treated with PGPR P. fluorescens and the results were compared with dual inoculation of P. fluorescens combined with ureolytic Staphylococcus epidermidis HJ2. The removal rate of the metals from the soil was more than 83% for Cd and Pb by the combined treatment compared to 17% by PGPR alone. Further, the dual treatment reduced the metal accumulation in the roots by more than 80%. The translocation factors for Cd and Pb in plant tissues in both treatments remained the same, suggesting that PGPR combined with the carbonate precipitation process does not hamper the transfer of essential metal ions into plant tissues from the soil.