• Journal of Microbiology
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• v.44 no.3
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• pp.263-268
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• 2006

Pleurotus ostreatus is a widely cultivated white-rot fungus. Owing to its considerable enzymatic versatility p. ostreatus has become the focus of increasing attention for its possible utility in biobleaching and bioremediation applications. Interactions between microorganisms can be an important factor in those processes. In this study, we describe the presence of a bacterial species associated with P. ostreatus strain G2. This bacterial species grew slowly (approximately 30 days) in the liquid and semi-solid media tested. When p. ostreatus was inoculated in solid media containing Tween 80 or Tween 20, bacterial microcolonies were detected proximal to the fungal colonies, and the relevant bacterium was identified via the analysis of a partial 16S rDNA sequence; it was determined to belong to the Burkholderia cepacia complex, but was not closely related to other fungus-isolated Burkholderiaceae. New specific primers were designed, and confirmed the presence of in vitro P. ostreatus cultures. This is the first time that a bacterial species belonging to the B. cepacia complex has been found associated with P. ostreatus.

• Journal of Microbiology
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• v.34 no.4
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• pp.320-326
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• 1996

To analyze the effects of host versus plasmid on survival of 2, 4-degrading bacteria in environmental samples, strains Pseudomonas cepacia/pJP4, Alcaligenes JMP228/pJP4, P. cepacia/p712, and Alcaligenes JMP228/p712 were separately inoculated into samples of field soil, paddy soil, lake water, and river water, and then the changes of their populations were measured. The strains used contained a 2, 4-D degradative plasmid, either pJP4 conferring fast-growing property to the host or p712 conferring slow-growing property, and were resistant to antibiotics such that the inoculated strains could be enumerated against the indigenous microbial populations. In sterile environmental samples, these strains were stably maintained at the levels used for inoculation, except in sterile paddy soil where Alcaligenes JMP228 strains died drapidly. In natural soil samples for four strains declined steadily with time, but in naturla water samples their polulations fell rapidly at the early phase and then remained almost constant. When the environmentla samples were treated with 2, 4-D, P. cepacia/pJP4 and P. cepacia/p712 maintained significant numbers, while Alcaligenes JMP228/pJP4 and Alcaligenes JMP228/p712 declined significantly in most of the samples. The results indicated that the survivability of genetically modified microorganisms could vary depending on the environments and that their abundance in the environments under s2, 4-D selection was markedly influenced by the nature of the 2, 4-D degradative plasmid as well as type of the host strain.

• Korean Journal of Environmental Agriculture
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• v.20 no.5
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• pp.335-339
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• 2001

Two successive in vitro experiments were carried out to examine the effect of MPS bacterial inoculation on growth, and nitrogen and phosphorus accumulation of maize plants under greenhouse condition in the same soil. There were four treatments, uninoculated control and three phosphate solubilizing bacterial inoculations, viz., Pseudomonas striata, Burkholderia cepacia and Serratia marcescens. The inoculated plants showed the higher plant height, total dry mass, nitrogen and phosphorus accumulation when compared to uninoculated control plants in both experiments. In the combined data analysis from two experiments, the plants inoculated with P. striata and B. cepacia showed significantly higher plant height, total dry mass and P accumulation when compared to S. marcescens inoculated plant and uninoculated control plants. The P. striata and B. cepacia inoculation enhanced total dry matter accumulation by 14% and phosphorus accumulation by 25% over the uninoculated control plants. The nitrogen and phosphorus concentration of maize plants were also increased due to MPS bacterial inoculation, however, the effect was not significant.

• KSBB Journal
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• v.15 no.4
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• pp.393-397
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• 2000

The cometaboic biodegradation conditionso f trichloroethylene(TCE) by Burkholderia cepacia G4 were optimized using response surface analysis. The experimental sets of phenol concentration temperature and pH were designed using central composite experimental design. The optimal conditions of phenol concentration temperature and pH were determined to be 0.91 ppm 21.5$^{\circ}C$ and 7.65 respectively by the Ridge analysis of the contour plot for TCE biodegradation rates. The TCE biodegradation rate could be enhanced up to 2.43 nmol.mg protein$.$min by response surface methodology.

• Korean Journal of Microbiology
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• v.30 no.1
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• pp.42-46
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• 1992

From the soil environment which is treated with herbicides. we isolated strain having high resistance against glyphosate. After being identified. the isolated strain was turned out to be Pseudomc~nu.c~c ~paciua nd to have intense tolerance lo the 10 mM glyphosate. The isolated strain shows slow, growth rate about twenty hours in glyphosate comparing with that in inorganic phosphate. As a result of confirming the p~~sitioonf glyphosate resistant gene. it was proved to exist in chromosome. After cloning it into E coli C600, transformants E. coli THC-101 and plasmid pGR19 were obtained.

• Journal of Life Science
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• v.9 no.1
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• pp.1-7
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• 1999

To isolate of antagonistic bacteria to Phytophthora capsici, which cause Phytophthora blight in red pepper, 237 isolates of Pseudomonas spp. and 260 isolates of Bacillus spp. were screened in selective media from rhizosphere soils of red pepper at Kyongsan, Kyongju, Yongchon and Euisung in Kyongbuk. Among total 497 isolates, 8 isolates of Pseudomonas spp and 4 isolates of Bacillus spp. inhibited the mycelial growth of Phytophthora capsici above 50$\%$ . These antagonistic bacteria showed more inhibitory effect on TSA (tryptic soy agar) than V-8 juice agar. Four isolates, P0704, P1201, B1101 and B1901, showing the most prominent antagonistic activity were selected and identified as P. cepacia (P0704, P1201), B. polymyxa (B1101) and B. subtilis (B1901), respectively. Cell free filtrates of these isolates were shown to inhibit zoosporangia germination and mycelial growth of p. capsici indicating that these isolates turned out to be bacteria producing antifungal substances. As a result of antagonistic test to Phytophthora blight in green house p. cepacia (P0704) showed the highest antagonistic effect with 46.7$\%$ and the rest of them were in the range of 13.4$\%$ to 26.7$\%$ .

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.804-811
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• 2001

In many Gram-negative bacteria, autoinducers, such as N-acyl-L-homoserine lactone(acyl-HSL) and its derivative molecules, mediate the cell-density-dependnet expression of certain operons. The current study identified the autoinducers produced by Burkholderia cepacia G4, a trichloroethylene-degrading lagoon isolate, using TLC bioassays with Agrobacterium tumefaciens NT1(pDCI141E33) and Chromobacterium violaceum CVO26, and a GC-MS analysis. The ${R_f}\;and\;{R_t}$ values and mass spectra were compared with those of synthetic compounds. Based on the analyses, it was confirmed that G4 produces N-hexanoyl (C6)-, N-octanoyl (C8)-, N-decanoyl (C10)-, N-dodecanoyl (C12)-HSL, and an unknown active species. The integration of the GC peak areas exhibited a ratio of C8-HSL:C10-HSL:C12-HSL at 3:17:1 with C6-HSL and C10-HSL production at trace and micromolar levels, respectively, in the culture supernatants. Nutants partially defective in producing acyl-HSLs were also partially defective in the biosynthesis of an antibiotic substance. These results indicate that the autoinducer-dependent gene regulation in G4 is dissimilar to the clinical B. cepacia strains isolated from patients with cystic fibrosis.

• Journal of Microbiology and Biotechnology
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• v.10 no.4
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• pp.568-571
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• 2000

Cepacidine A was previously isolated as a novel antifungal antibiotic from the culture broth of Pseudomonas cepacia AF2001. It exhibits a potent in vitro antifungal activity against various plant pathogenic fungi, such as Plasmopora veticola on grapes, Septoria nodorum and Fusarium culmorum on wheat, as well as Colletotrichum lagenarium on cucumbers. Accordingly, this study was conducted to evaluate the potential crop protection activity of strain P. cepacia AF2001. The strain was tested in semi-greenhouse biocontrol assays, and showed an excellent biological activity against Pythium ultimum in cotton and cucumbers; however, only a minor activity against Rhizoctonia aolani in cotton was observed. Furthermore, the nematodes Haemonchus contortus and Trichostrongylus only exhibited a moderated activity in the in vitro larval development assay with no activity in the in vivo animal model.

• Korean journal of applied entomology
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• v.26 no.2 s.71
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• pp.89-97
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• 1987

Antagonistic microorganisms from rhizosphere soil were isolated, identified, and applied successfully as the biocontrol agents of damping-off caused by Rhizoctonia spp. Rhizosphere antagonists isolated from rhizosphere soil were identified as Trichoderma viride, T. harzianum, T. hamatum, T. polysporum, Gliocladium sp., Pseudomonas fluorescence, P. stutzeri, P. cepacia, Enterobacter sp., Serratia sp. and Erwinia herbicola. Of these, the most promising ones in vitro were T. virdie, T. harzianum, Gliocladium sp., Serratia sp., P. stutzeri, and P. cepacia. These above six antagonists were efficient in reducing disease incidence to $40{\sim}70%$ when the reselected rhizosphere antagonists preparations were applied to the soil at $10^6$ propagules per gram. Among six antagonists, T. viride was the most promising biocontrol agents against R. solani isolates in soil. The suppressive effect was more evident in steam-sterilized soil than in non-sterilized field soil.

• Korean Journal of Microbiology
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• v.30 no.1
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• pp.47-52
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• 1992

This study describes isolation and identification of a soil bacterium which is degradable of phosphinothricin and improvement of the isolated strain by using mutagenesis and spheroplast fusion. The experiment was performed to search for a possibility of development of a new strain which is both PPT-degradable and glyphosate-resistant by using interspecies cell fusion between the PPT-degrading bacterium. Pseudornonu.\ puucimohlis and a glyphosate -resistant strain, Pseudornonu.~ cc,pucicl. Auxotrophic mutants were obtained by the treatement of P. puucimohili.\ with ethylmethanosulfate, and used to cell fusion. Lysozyme and EDTA were used to spheroplast formation and regeneration rates :)f the spheroplast were 6.5'%1 in P. pauc.irnohili.\ and 8.8% in P.ci,j~u[,i(lr, espctively. Polyethylenglycol 5.000 was used to cell fusion as fusogen. The fusant\ulcorner F1. F2. F\ulcorner and F4 werc- obtained by the intra- and interspecies cell fusion. The fusant Fl of intraspecies cell fusion was higher to the wild type by 1 I'%l in PPT degrading ability, and the fusant F3 of inierspesis cell fusion developed plyphosatc-resistant and PPI-dcgrading ability which were propertics of two parental strains.