• The Plant Pathology Journal
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• v.35 no.5
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• pp.445-458
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• 2019

The lipopolysaccharide (LPS) composed of lipid A, core, and O-antigen is the fundamental constituent of the outer membrane in gram-negative bacteria. This study was conducted to investigate the roles of LPS in Burkholderia glumae, the phytopathogen causing bacterial panicle blight and seedling rot in rice. To study the roles of the core oligosaccharide (OS) and the O-antigen region, mutant strains targeting the waaC and the wbiFGHI genes were generated. The LPS profile was greatly affected by disruption of the waaC gene and slight reductions were observed in the O-antigen region following wbiFGHI deletions. The results indicated that disruption in the core OS biosynthesis-related gene, waaC, was associated with increased sensitivity to environmental stress conditions including acidic, osmotic, saline, and detergent stress, and to polymyxin B. Moreover, significant impairment in the swimming and swarming motility and attenuation of bacterial virulence to rice were also observed in the waaC-defective mutant. The motility and virulence of O-antigen mutants defective in any gene of the wbiFGHI operon, were not significantly different from the wild-type except in slight decrease in swimming and swarming motility with wbiH deletion. Altogether, the results of present study indicated that the LPS, particularly the core OS region, is required for tolerance to environmental stress and full virulence in B. glumae. To our knowledge, this is the first functional study of LPS in a plant pathogenic Burkholderia sp. and presents a step forward toward full understanding of B. glumae pathogenesis.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.376-383
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• 2005

Alcaligenes sp. JMP228 carrying 2,4­dichlorophenoxyacetic acid (2,4-D) degradative plasmid pJP4 was inoculated into natural soil, and transfer of the plasmid pJP4 to indigenous soil bacteria was investigated with and without 2,4-D amendment. Plasmid pJP4 transfer was enhanced in the soils treated with 2,4-D, compared to the soils not amended with 2,4-D. Several different transconjugants were isolated from the soils treated with 2,4-D, while no indigenous transconjugants were obtained from the unamended soils. Inoculation of the soils with both the donor Alcaligenes sp. JMP228/pJP4 and a recipient Burkholderia cepacia DBO 1 produced less diverse transconjugants than the soils inoculated with the donor alone. Repetitive extragenic palindromic-polymerase chain reaction (REP-PCR) analysis of the transconjugants exhibited seven distinct genomic DNA fingerprints. Analysis of 16S rDNA sequences indicated that the transconjugants were related to members of the genera Burkholderia and Pandoraea. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes revealed that inoculation of the donor caused clear changes in the bacterial community structure of the 2,4-D­amended soils. The new 16S rRNA gene bands in the DGGE profile corresponded with the 16S rRNA genes of 2,4-D­degrading transconjugants isolated from the soil. The results indicate that introduction of the 2,4-D degradative plasmid as Alcaligenes sp. JMP228/pJP4 has a substantial impact on the bacterial community structure in the 2,4-D-amended soil.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.10
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• pp.1461-1468
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• 2014

This study was aimed to examine the antibacterial and antioxidative properties of seven edible plants from Thailand to develop alternative antibiotics as feed additives. The plants include Citrus aurantifolia Swingle (Lime) fruits and its leaves, Sesbania grandiflora L. (Agati sesbania) leaves, Piper sarmentosum Roxb (Wild betal) leaves, Curcuma domestica Valeton (Turmeric) roots, Morinda citrifolia L. (Beach mulberry) leaves, Cassia siamea britt (Siamea cassia) leaves, and Cocos nucifera L. (Coconut) peels. The plants were extracted by methanol, n-hexane, chloroform, ethyl acetate, butanol and water. Antibacterial activities with minimum inhibitory concentration (MIC) were determined by agar diffusion assay against Escherichia coli, Burkholderia sp., Haemopilus somnus, Haemopilus parasuis, and Clostridium perfringens that were considered pathogenic strains in livestock infection. Methanol extracts of C. aurantifolia Swingle fruits and leaves showed the broadest spectrum of antibacterial activities except for C. perfringens. Butanol extract of S. grandiflora L. leaves showed the strongest activity against Burkholderia sp. with MIC, $135{\mu}g/mL$. P. sarmentosum Roxb leaves showed antibacterial activities against E. coli, Burkholderia sp. and H. parasuis. Ethyl acetate and water extracts from C. domesitca Valeton roots showed MIC of $306{\mu}g/mL$ and $183{\mu}g/mL$, respectively against only C. perfringens. Antioxidative activity was determined by 2-diphenyl-2-picryl hydrazyl photometric assay. The methanol extracts of C. aurantifolia Swingle fruits and P. sarmentosum Roxb leaves showed the highest antioxidant activity among all the extracts with 3.46 mg/mL and 2.70 mg/mL effective concentration 50% ($EC_{50}$) values, respectively. Total contents of phenolics and flavonoids were measured from the plant extracts. Methanol extracts of S. grandiflora L. and chloroform extracts of C. domestica Valeton were found to have the highest amount of total phenolics, 41.7 and $47.8{\mu}g/mL$, respectively. Flavonoid content of methanol extracts in S. grandiflora L. T was $22.5{\mu}g/mL$ and the highest among plant extracts tested. These results indicated that C. aurantifolia Swingle, S. grandiflora L., P. sarmentosum Roxb, and C. domestica Valeton have antibacterial and antioxidant activities and can be used as alternative antibiotics or potential feed additives for the control of animal pathogenic bacteria.

• Korean Journal of Microbiology
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• v.41 no.1
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• pp.13-17
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• 2005

The aim of this work was to investigate the N-terminal amino acid sequence of catechol 2,3-dioxygenase isolated from Delftia sp. JK-2, which could utilize aniline as sole carbon, nitrogen and energy source. Molecular weight of the enzyme was determined to approximately 35 kDa by SDS-PAGE. N-terminal amino acid sequence of C2,3O from strain JK-2 was $^1MGVMRIGHASLKVMDMDAAVRHYENV^{26}$, and exhibited high sequence similarity with that of C2,3O from Pseudomonas sp., Comamonas sp. JS765, Comamonas test-osteroni, or Burkholderia sp. RP007. Approximately 950-bp C2,3O was obtained through PCR using the primers derived from N-terminal amino acid sequence. Analysis of the DNA sequence revealed that the deduced 296 amino acid sequences were determined, and it showed $100\%$ identity with C2,3O from Pseudomonas sp. AW-2 and $97\%$ similarity with Comamonas sp. JS765.

• Research in Plant Disease
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• v.25 no.4
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• pp.179-187
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• 2019

This study was carried out to test the antimicrobial activities of nano metal hybrid materials produced by plasma technologies (radio frequency-thermal plasma system and direct current sputtering system) against microbes isolated from cucurbit (watermelon, pumpkin, and gourd) seeds. Eight different nano metal hybrid materials and four carriers were tested against five different fungal and ten different bacterial isolates in vitro. Among the tested nano metal hybrid material, Brass/CaCO₃ (1,000 ppm) exhibited 100% antimicrobial effect against all the five tested fungi. However, nano metal hybrid material Brass/CaCO₃ (1,000 ppm) inhibited only four bacterial isolates, Weissella sp., Rhodotorula mucilaginosa, Burkholderia sp., and Enterococcus sp. at 100% level, and did not inhibited other six bacterial isolates. Nano metal hybrid material graphite-nickel (G-Ni) showed 100% inhibition rate against Rhizopus stolonifer and 52.94-71.76% inhibition rate against four different fungal isolates. Nano metal hybrid material G-Ni did not show any inhibition effects against tested ten bacterial isolates. In summary, among the tested eight different nano metal hybrid materials and four carriers, Brass/CaCO₃ showed inhibition effects against five fungal isolates and four bacterial isolates, and G-Ni showed variable inhibition effects (52.94-100%) against five fungal isolates and did not show any inhibition effects against all the bacterial isolates.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2005.11a
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• pp.179-179
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• 2005

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.4
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• pp.84-89
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• 2011

Cellulose-degrading bacteria were isolated and identified from cocopeat which has a good quality as a bulking agent in composting. Various bacteria from different sourecs of cocopeat were detected on CMC agar media, and these were found to be Burkholderi2a sp., Bacillu subtilis, Sphingomonas sp., Rhodotorula sp. & Pseudomonas sp. etc. Among these, four bacteria were further selected and analyzed for their biochemical characteristics and CMCase activities. CMCase activities of four bacteria, P. aeruginosa, P. stutzeri, B. subtilis, and P. luteola were found to be 83%, 40%, 8%, 6%, respectively, compared with that of the standard strain Cellulomonas sp.

• Microbiology and Biotechnology Letters
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• v.35 no.1
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• pp.1-10
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• 2007

The 44 endophytic bacterial strains were isolated from surface-sterilized root of rice cultivated in seven different locations of Chungcheong province, Korea. Each isolate was introduced into rice seedlings grown gnotobiotically by inoculating scissor-cut first true leaf with cell suspensions, and the colonization capacity of each isolate in root tissue was analyzed at 7 days after inoculation. Sixteen out of 44 isolates were re-isolated from root successfully with the frequency of $10^{3-5}$ CFU/g tissue. Interestingly, seven out of 16 isolates were identified as Burkholderia species. The identity between inoculated strains and re-isolates was confirmed by genomic finger-printing and 16S rDNA sequence analysis. By a confocal laser scanning microscopic observation it was revealed that KJ001 strain, one of the sixteen isolates tagged with gfp colonized in root tissue especially around xylem. Six out of seven Burkholderia strains obtained in this study showed antagonizing activities against seven different fungal pathogens, contain nifH gene, and five of them enhanced growth of cucumber over 30%. The isolates showed no hypersensitive response on tobacco leaves and no pathogenecity in rice. From these results it was found that the endophytic Burkholderia strains will be useful in agriculture to develop a biocontrol agent or a bio-fertilizer.

• Journal of Microbiology
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• v.35 no.2
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• pp.117-122
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• 1997

Several dominant 4-CPA-degrading bacteria were isoalted from agricultural soils. Most of the isolates were identified as Burkholderia species by fatty acid methyl ester (FAME) analysis, but they were idstinct in chromosomal patterns obtained by PCR amplification of repetitive extragenic palindromic (REP) sequences. These strains were generally restricted in their substrate utilization capabilities. The 4-CPA degradative enzymes were idnducible by 4-CPA and some isolates appeared to mineralize 4-CPA via formation of 4-chlorophenol and 4-chlorocatechol as intermediates during its biodegradation pathway. Plasmid DNAs were not detected from most of the isoaltes and their 4-CPA genes wer on the chromosomal DAN. The 4-CPA degradation patterns in axenic cultures and natural soils varied depending on the strains and soils. The inoculation of 4-CPA degraders much improved the removal of 4-CPA from the 4-CPA treated soils.

• Journal of Microbiology and Biotechnology
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• v.27 no.6
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• pp.1138-1149
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• 2017

The use of microalgal biomass is an interesting technology for the removal of heavy metals from aqueous solutions owing to its high metal-binding capacity, but the interactions with bacteria as a strategy for the removal of toxic metals have been poorly studied. The goal of the current research was to investigate the potential of Burkholderia tropica co-immobilized with Chlorella sp. in polyurethane discs for the biosorption of Hg(II) from aqueous solutions and to evaluate the influence of different Hg(II) concentrations (0.041, 1.0, and 10 mg/l) and their exposure to different contact times corresponding to intervals of 1, 2, 4, 8, 16, and 32 h. As expected, microalgal bacterial biomass adhered and grew to form a biofilm on the support. The biosorption data followed pseudo-second-order kinetics, and the adsorption equilibrium was well described by either Langmuir or Freundlich adsorption isotherm, reaching equilibrium from 1 h. In both bacterial and microalgal immobilization systems in the co-immobilization of Chlorella sp. and B. tropica to different concentrations of Hg(II), the kinetics of biosorption of Hg(II) was significantly higher before 60 min of contact time. The highest percentage of biosorption of Hg(II) achieved in the co-immobilization system was 95% at pH 6.4, at 3.6 g of biosorbent, $30{\pm}1^{\circ}C$, and a mercury concentration of 1 mg/l before 60 min of contact time. This study showed that co-immobilization with B. tropica has synergistic effects on biosorption of Hg(II) ions and merits consideration in the design of future strategies for the removal of toxic metals.