• Journal of Microbiology
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• 제44권3호
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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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• 제45권3호
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• pp.275-279
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• 2007

The aims of this study were to detect Burkholderia cepacia complex (Bcc) strains in a cohort of Cystic Fibrosis patients (n=276) and to characterize Bcc isolates by molecular techniques. The results showed that 11.23% of patients were infected by Bcc. Burkholderia cenocepacia lineage III-A was the most prevalent species (64.3%) and, of these, 10% was cblA positive and 50% esmR positive. Less than half of the strains were sensitive to ceftazidime, meropenem, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole. About half of the strains (41%) had homogeneous profiles, suggesting cross-transmission. The infection by B. cenocepacia was associated to a high rate of mortality (p=0.01).

• The Plant Pathology Journal
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• 제26권3호
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• pp.223-230
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• 2010

The Burkholderia cepacia complex isolates causing bacterial fruit rot of apricot were characterized by speciesspecific PCR tests, recA-HaeIII restriction fragment length polymorphism (RFLP) assays, rep-PCR genomic fingerprinting, recA gene sequencing, and multilocus sequence typing (MLST) analysis. Results indicated that the isolates Bca 0901 and Bca 0902 gave positive amplifications with primers specific for B. vietnamiensis while the two bacterial isolates showed different recA-RFLP and rep-PCR profiles from those of B. vietnamiensis strains. In addition, the two bacterial isolates had a higher proteolytic activity compared with that of the non-pathogenic B. vietnamiensis strains while no cblA and esmR marker genes were detected for the two bacterial isolates and B. vietnamiensis strains. The two bacterial isolates were identified as Burkholderia seminalis based on recA gene sequence analysis and MLST analysis. Overall, this is the first characterization of B. seminalis that cause bacterial fruit rot of apricot.

• Journal of Microbiology and Biotechnology
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• 제34권8호
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• pp.1609-1616
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• 2024

The Burkholderia cepacia complex (Bcc) consists of opportunistic pathogens known to cause pneumonia in immunocompromised individuals, especially those with cystic fibrosis. Treating Bcc pneumonia is challenging due to the pathogens' high multidrug resistance. Therefore, inhalation therapy with tobramycin powder, which can achieve high antibiotic concentrations in the lungs, is a promising treatment option. In this study, we investigated potential mechanisms that could compromise the effectiveness of tobramycin therapy. By selecting for B. cenocepacia survivors against tobramycin, we identified three spontaneous mutations that disrupt a gene encoding a key enzyme in the biosynthesis of cobalamin (Vitamin B₁₂). This disruption may affect the production of succinyl-CoA by methylmalonyl-CoA mutase, which requires adenosylcobalamin as a cofactor. The depletion of cellular succinyl-CoA may impact the tricarboxylic acid (TCA) cycle, which becomes metabolically overloaded upon exposure to tobramycin. Consequently, the mutants exhibited significantly reduced reactive oxygen species (ROS) production. Both the wild-type and mutants showed tolerance to tobramycin and various other bactericidal antibiotics under microaerobic conditions. This suggests that compromised ROS-mediated killing, due to the impacted TCA cycle, underlies the mutants' tolerance to bactericidal antibiotics. The importance of ROS-mediated killing and the potential emergence of mutants that evade it through the depletion of cobalamin (Vitamin B₁₂) provide valuable insights for developing strategies to enhance antibiotic treatments of Bcc pneumonia.

• Journal of Microbiology and Biotechnology
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• 제29권10호
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• pp.1495-1505
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• 2019

The Burkholderia cepacia complex (BCC) is capable of remaining viable in low-nutrient environments and harsh conditions, posing a contamination risk in non-sterile pharmaceutical products as well as a challenge for detection. To develop optimal recovery methods to detect BCC, three oligotrophic media were evaluated and compared with nutrient media for the recovery of BCC from autoclaved distilled water or antiseptic solutions. Serial dilutions ($10^{-1}$ to $10^{-12}CFU/ml$) of 20 BCC strains were inoculated into autoclaved distilled water and stored at $6^{\circ}C$, $23^{\circ}C$ and $42^{\circ}C$ for 42 days. Six suspensions of Burkholderia cenocepacia were used to inoculate aqueous solutions containing $5{\mu}g/ml$ and $50{\mu}g/ml$ chlorhexidine gluconate (CHX) and $10{\mu}g/ml$ benzalkonium chloride (BZK), and stored at $23^{\circ}C$ for a further 199 days. Nutrient media such as Tryptic Soy Agar (TSA) or Tryptic Soy Broth (TSB), oligotrophic media (1/10 strength TSA or TSB, Reasoner's $2^{nd}$ Agar [R2A] or Reasoner's $2^{nd}$ Broth [R2AB], and 1/3 strength R2A or R2AB) were compared by inoculating these media with BCC from autoclaved distilled water and from antiseptic samples. The recovery of BCC in water or antiseptics was higher in culture broth than on solid media. Oligotrophic medium showed a higher recovery efficiency than TSA or TSB for the detection of 20 BCC samples. Results from multiple comparisons allowed us to directly identify significant differences between TSA or TSB and oligotrophic media. An oligotrophic medium pre-enrichment resuscitation step is offered for the United States Pharmacopeia (USP) proposed compendial test method for BCC detection.

• Journal of Microbiology and Biotechnology
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• 제27권12호
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• pp.2211-2220
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• 2017

Chlorhexidine gluconate (CHX) and benzalkonium chloride (BZK) formulations are frequently used as antiseptics in healthcare and consumer products. Burkholderia cepacia complex (BCC) contamination of pharmaceutical products could be due to the use of contaminated water in the manufacturing process, over-diluted antiseptic solutions in the product, and the use of outdated products, which in turn reduces the antimicrobial activity of CHX and BZK. To establish a "afe use" period following opening containers of CHX and BZK, we measured the antimicrobial effects of CHX ($2-10{\mu}g/ml$) and BZK ($10-50{\mu}g/ml$) at sublethal concentrations on six strains of Burkholderia cenocepacia using chemical and microbiological assays. CHX (2, 4, and $10{\mu}g/ml$) and BZK (10, 20, and $50{\mu}g/ml$) stored for 42 days at $23^{\circ}C$ showed almost the same concentration and toxicity compared with freshly prepared CHX and BZK on B. cenocepacia strains. When $5{\mu}g/ml$ CHX and $20{\mu}g/ml$ BZK were spiked to six B. cenocepacia strains with different inoculum sizes ($10^0-10^5CFU/ml$), their toxic effects were not changed for 28 days. B. cenocepacia strains in diluted CHX and BZK were detectable at concentrations up to $10^2CFU/ml$ after incubation for 28 days at $23^{\circ}C$. Although abiotic and biotic changes in the toxicity of both antiseptics were not observed, our results indicate that B. cenocepacia strains could remain viable in CHX and BZK for 28 days, which in turn, indicates the importance of control measures to monitor BCC contamination in pharmaceutical products.

• The Plant Pathology Journal
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• 제27권1호
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• pp.59-67
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• 2011

A bacterial strain CH-67 which exhibits antagonism towards several plant pathogenic fungi such as Botrytis cinerea, Fulvia fulva, Rhizoctonia solani, Sclerotinia sclerotiorum, Colletotrichum sp. and Phytophthora sp. was isolated from forest soil by a chitin-baiting method. This strain was identified as Burkholderia cepacia complex (Bcc) and belonging to genomovar IX (Burkholderia pyrrocinia) by colony morphology, biochemical traits and molecular method like 16S rRNA and recA gene analysis. This strain was used to develop a bio-fungicide for the control of tomato leaf mold caused by Fulvia fulva. Various formulations of B. pyrrocinia CH-67 were prepared using fermentation cultures of the bacterium in rice oil medium. The result of pot experiments led to selection of the wettable powder formulation CH67-C containing modified starch as the best formulation for the control of tomato leaf mold. CH67-C, at 100-fold dilution, showed a control value of 85% against tomato leaf mold. Its disease control efficacy was not significantly different from that of the chemical fungicide triflumidazole. B. pyrrocinia CH-67 was also effective in controlling damping-off caused by Rhizoctonia solani PY-1 in crisphead lettuce and tomato plants. CH67-C formulation was recognized as a cell-free formulation since B. pyrrocinia CH-67 was all lethal during formulation process. This study provides an effective biocontrol formulation of biofungicide using B. pyrrocinia CH-67 to control tomato leaf mold and damping-off crisphead lettuce and tomato.

• 미생물학회지
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• 제40권4호
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• pp.313-319
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• 2004

울산석유화학공단과 인접한 지역(선암)및 농촌지역(대암)의 산림토양에서 내산성 종속영양세균 및 나프탈렌분해세균의 분포와 특성을 조사하였다. 토양 pH의 평균은 선암과 대암에서 각각 3.8과 4.6으로 측정되었다. 종속영양세균과 나프탈렌분해세균을 최확수치(MPN)법으로 계수하였으며, 선암의 경우 pH 7.0과 pH 4.0에서 생장하는 종속영양세균 수의 중앙간은 각각 $5.3{\times}10^7\;3.3{\times}10^7$ MPN/dried Soil g이었고, 나프탈렌분해세균 수의 중앙간은 pH 7.0과 4.0에서 각각 $5.6{\times}10^4$ 와 $4.0{\times}10^5$ MPN/dried soil g이었다. 대암에서 측정한 종속영양세균수의 중앙간은 두 pH 모두 선암에서보다 많았으나 나프탈렌분해세균의 농도는 선암이 대암보다 높았다. MPN시험관과 농화배양으로부터 17개의 나프탈렌분해세균을 분리하였으며, 이들은 Sphingomonas paucimobilis, Brevundimonas vesicularis, Burkholderia cepacia, Ralstonia pickettii, Pseudomonas fluorescens, Chryseomonas luteola 등으로 동정되었다. 분리한 17개 균주 중 6개는, 최소배지에서의 나프탈렌분해 활성이 PH 7.0에 비해 PH 4.0에서 더 높았으나 영양배지에 접종하였을 때의 생장정도는 pH 4.0이 pH 7.0보다 더 크지 않았다. 배지의 pH가 분리한 세균의 세포막 지방산 조성을 변화시켜 나프탈렌분해 활성에 영향을 주는 것으로 생각된다.

• Mycobiology
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• 제36권4호
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• pp.249-254
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• 2008

Minimal growth inhibitory concentrations (MICs) of chitosan acetate (M.W. 60 kDa) on heterotrophic bacteria (strains MK1, S, and R) isolated from the soft-rotten tissues of Neungee mushroom (Sarcodon aspratus) were measured. The slimy substance produced by the MK1 strain was responsible for the diseased mushroom’s appearance. The S and R strains were members of the Burkholderia cepacia complex. These strains showed different levels of susceptibility toward chitosan acetate. The MIC of chitosan acetate against the MK1 and S strains was 0.06%. The MIC against the R strain was greater than 0.10%. Survival fractions of the MK1 and S strains at the MIC were $3\;{\times}\;10^{-4}$ and $1.4\;{\times}\;10^{-3}$ after 24 h, and $2\;{\times}\;10^{-4}$ and $7\;{\times}\;10^{-4}$ after 48 h, respectively. Survival fractions of the R strain after 24 and 48 hr at 0.1% chitosan acetate were $1\;{\times}\;10^{-2}$ and $6.9\;{\times}\;10^{-3}$, respectively. Compared to the MK1 and S strains, the low susceptibility of the R stain towards chitosan acetate could be due to the ability of the R strain to utilize chitosan as a carbon source. Thirty-eight percent of Neungee pieces treated in a 0.06% chitosan acetate solution for $2{\sim}3$ second did not show any bacterial growth at 4 days, whereas bacterial growth around untreated mushroom pieces occurred within 2 days. These data suggest that chitosan acetate is highly effective in controlling growth of indigenous microorganisms on Neungee. The scanning electron micrographs of the MK1 strain treated with chitosan revealed a higher degree of disintegrated and distorted cellular structures.

• 한국지하수토양환경학회지:지하수토양환경
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• 제8권4호
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• pp.27-35
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• 2003

연구대상부지는 주로 선캄브리아기의 변성암의 일종인 편마암으로 형성되어 있으며, 토양은 하천에 축적된 비교적 투수성이 높은 매질로 구성된 충적토를 모재로 형성되었다. 지하수위는 지표로부터 평균 3.5m 깊이에서 나타나며. 하류 방향으로 갈수록 깊어지는 경향을 나타내었다. 대상부지의 수리전도도는 자갈이 혼재된 조립질 모래층은 5.0${\times}$$10^{-2}$∼1.85${\times}$$10^{-1}$ cm/sec, 세립질 모래층은 $1.5{\times}$$10^{-3}$ to 7.6${\times}$$10^{-3}$ cm/sec, 복토층은 $10^{-4}$ cm/sec 이하로 나타났다. 연구대상부지의 주오염물질은 Toluene, Ethylbenzene, xylene(이하 TEX)이며, 오염토양층은 1.5 m내외로 깊이별 토양중 TEX의 농도는 추정오염원으로부터 70m떨어진 곳의 질이 2.4∼4.8m에서 가장 높았다. 지하수중 TEX의 농도는 추정오염원의 주변지역에서 가장 높았으며, 조사대상부지의 중앙지역과 남서쪽지역에서도 높게 나타났으며, 이러한 지하수중 TEX의 농도분포는 토양중의 TEX의 농도분포와 상당히 일치하는 경향을 보이고 있다. 연구대상부지에 서식하고 있는 톨루엔 분해 호기성세균의 주종은 Pseudomonas fluorescence, Burkholderia cepacia, Acinetobactor lwoffi로 확인되었다. 지하수 분석결과 전자수용체인 용존산소, 질산염, 황산염 등이 배경지역에 비해 오염지역에서 상당히 낮게 나타났다. 한편, 연구대상부지에서의 계산된 전체 자연저감속도는 0.0017da $y^{-1}$이며, 1차 생분해속도는 0.0008 da $y^{-1}$로 계산되었다.