• 대한약침학회지
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• 제19권4호
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• pp.312-318
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• 2016

Objectives: Bacterial resistant infections have become a global health challenge and threaten the society's health. Thus, an urgent need exists to find ways to combat resistant pathogens. One promising approach to overcoming bacterial resistance is the use of herbal products. Green tea catechins, the major green tea polyphenols, show antimicrobial activity against resistant pathogens. The present study aimed to investigate the effect of catechins, green tea extract, and methylxanthines in combination with gentamicin against standard and clinical isolates of Staphylococcus aureus (S. aureus) and the standard strain of Pseudomonas aeruginosa (P. aeruginosa). Methods: The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values of different agents against bacterial strains were determined. The interactions of green tea extract, epigallate catechin, epigallocatechin gallate, two types of methylxanthine, caffeine, and theophylline with gentamicin were studied in vitro by using a checkerboard method and calculating the fraction inhibitory concentration index (FICI). Results: The MICs of gentamicin against bacterial strains were in the range of $0.312-320{\mu}g/mL$. The MIC values of both types of catechins were $62.5-250{\mu}g/mL$. Green tea extract showed insufficient antibacterial activity when used alone. Methylxanthines had no intrinsic inhibitory activity against any of the bacterial strains tested. When green tea extract and catechins were combined with gentamicin, the MIC values of gentamicin against the standard strains and a clinical isolate were reduced, and synergistic activities were observed (FICI < 1). A combination of caffeine with gentamicin did not alter the MIC values of gentamicin. Conclusion: The results of the present study revealed that green tea extract and catechins potentiated the antimicrobial action of gentamicin against some clinical isolates of S. aureus and standard P. aeruginosa strains. Therefore, combinations of gentamicin with these natural compounds might be a promising approach to combat microbial resistance.

• Journal of Microbiology and Biotechnology
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• 제16권3호
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• pp.450-456
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• 2006

Pseudomonas fluorescens MC07 is a growth-promoting rhizobacterium that suppresses mycelial growth in fungi such as Rhizoctonia solani, Pythium ultimum, Fusarium oxysporum, and Phytophthora capsici. To determine the role of the bacterium's antifungal activity in disease suppression, we screened 2,500 colonies generated by Tn5lacZ insertions, and isolated a mutant 157 that had lost antifungal activity. The EcoRI fragment carrying Tn5lacZ was cloned into pBluescript II SK(+) and used as a probe to isolate wild-type clones from a genomic library of the parent strain, MC07. Two overlapping cosmid clones, pEH4 and pEH5, that had hybridized with the mutant clone were isolated. pEH4 conferred antifungal activity to the heterologous host P.fluorescens strain 1855.344, whereas pEH5 did not. Through transposon mutagenesis of pEH4 and complementation analyses, we delineated the 14.7-kb DNA region that is responsible for the biosynthesis of an antifungal compound. DNA sequence analysis of the region identified 11 possible open reading frames (ORF), ORF1 through ORF11. A BLAST search of each putative protein implied that the proteins may be involved in an antifungal activity similar to polyketides.

• 한국미생물·생명공학회지
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• 제35권3호
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• pp.245-249
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• 2007

토양 시료를 대상으로 3.4-dichloroaniline (DCA)를 함유한 최소배지에서의 집식배양과 배양 후 HPLC에 의한 잔류분석을 통해 3,4-DCA의 분해 능력이 우수한 균주 Pseudomonas sp. KB35B를 분리하였다. 분리균 KB35B는 1/10 LB배지에 함유된 50 ppm의 3,4-DCA를 12시간만에 완전히 제거하였다. 이외에도 분리균 KB35B는 3-chloroaniline (CA), 4-CA 및 2,4-DCA의 분해 활성을 나타내었으나 2,5-DCA와 3,5-DCA에 대한 분해활성을 가지고 있지는 않았다. 또한, 분리균 KB35B에서 3,4-DCA의 유도에 의한 catechol 2,3-dioxygenase 활성의 증가가 관찰되었다. 이상의 결과로부터 catechol 2,3-dioxygenase이 3,4-DCA 분해에 관여하는 중요한 효소군중의 하나로 생각된다.

• 미생물학회지
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• 제28권1호
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• pp.41-46
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• 1990

자연환경으로부터 분리한 DJ-12 균주는 4CBA 및 4CB를 비롯하여 그 대사산물인 4OHBA와 PCA를 분해하여 단일 탄소원으로 이용하였다. DJ-12 균주에서 4CBA 및 4CB분해유전자는 약 65kb 크기의 plasmid인 pDJ121에 존재하였으며, 이 pDJ121은 ExoRI, HindIII, SalI 그리고 PslI의 절단부위를 각각 9, 11, 10 그리고 19개씩 가지고 있었다. EcoRI으로 처리한 pDJ121 절편을 pKT230에 ligation 시켜 재조합 vector인 pDK450을 만들었으며, 이를 Pseudomonas putida KT2440에 transformation 시켜 얻은 cloned cell 에서는 4CBA 분해유전자가 잘 발현되었다.

• Journal of Microbiology and Biotechnology
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• 제34권5호
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• pp.1040-1050
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• 2024

To isolate and analyze bacteria with Verticillium wilt-resistant properties from the fermentation residue of kitchen wastes, as well as explore their potential for new applications of the residue. A total of six bacterial strains exhibiting Verticillium wilt-resistant capabilities were isolated from the biogas residue of kitchen waste fermentation. Using a polyphasic approach, strain ZL6, which displayed the highest antagonistic activity against cotton Verticillium wilt, was identified as belonging to the Pseudomonas aeruginosa. Bioassay results demonstrated that this strain possessed robust antagonistic abilities, effectively inhibiting V. dahliae spore germination and mycelial growth. Furthermore, P. aeruginosa ZL6 exhibited high temperature resistance (42℃), nitrogen fixation, and phosphorus removal activities. Pot experiments revealed that P. aeruginosa ZL6 fermentation broth treatment achieved a 47.72% biological control effect compared to the control group. Through activity tracking and protein mass spectrometry identification, a neutral metalloproteinase (Nml) was hypothesized as the main virulence factor. The mutant strain ZL6ߡNml exhibited a significant reduction in its ability to inhibit cotton Verticillium wilt compared to the strain P. aeruginosa ZL6. While the inhibitory activities could be partially restored by a complementation of nml gene in the mutant strain ZL6CMߡNml. This research provides a theoretical foundation for the future development and application of biogas residue as biocontrol agents against Verticillium wilt and as biological preservatives for agricultural products. Additionally, this study presents a novel approach for mitigating the substantial amount of biogas residue generated from kitchen waste fermentation.

• 생명과학회지
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• 제20권5호
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• pp.662-669
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• 2010

폐식용유에서 지방분해효소를 생산하는 세균을 분리하였고, PIBWIN 세균동정 방법으로 생리 생화학적 특성을 조사하여 확인한 결과 Pseudomonas sp. OME로 동정하였다. 여러 기질로 지방분해효소 생산을 조사한 결과 올리브유에서 6.1 U/ml의 생산력을 나타내었다. 물리적 인자인 배양시간, 온도. pH 및 올리브유와 효모 추출액의 영양인자에 의한 지방분해효소 생산 조건을 조사 하였다. 효소의 분비는 배양시간. 올리브유 와 효모 추출액의 농도에 강한 영향을 받았으며, RSM을 이용한 최적화는 이들 인자를 가지고 조사하였다. RSM을 이용한 지방분해효소 생산은 배양시간. 올리브유와 효모 추출액의 농도가 48 hr, 0.3 g, 및 0.9 ml에서 최적 생산조건을 나타냈다.

• Journal of Microbiology
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• 제40권4호
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• pp.289-294
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• 2002

The fungal strain SW-3 having antimicrobial activity was isolated from soil of crucified plants in Pocheon, Kyungki-Do, Korea. Strain SW-3 was identified as Alternaria brassicicola by its morphological characteristics, and confirmed by the analysis of the 18S gene and ITS regions of rDNA. The fungus showed a similarity of 99% with Alternaria brassicicola in the 18S rDNA sequence analysis. A. brassicicola has been reported to produce an antitumor compound, called depudecin. We found that strain SW-3 produced antimicrobial metabolites, in addition to depudecin, during sporulation under different growth conditions. The metabolite of the isolated fungus was found to have strong antifungal activity against Microsporium canis and Trichophyton rubrum, and antibacterial activity against Staphylococcus aureus and Pseudomonas aerogenes. The amount and kind of metabolites produced by the isolate were affected by growth conditions such as nutrients and growth periods.

• 미생물학회지
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• 제28권2호
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• pp.145-150
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• 1990

The effects of environmental factors on degradation of Aroclor 1242 were investigated with four Gram-negative bacterial isolates. Their biodegradabilities of the Aroclor were well correlated to their growth rates on the Aroclor added as a sole carbon and energy source. The optimum concentration of the Aroclor for biodegradation of the substrate in MM2 medium was 0.5mg/ml in HK-100, HK-123, and MS-1003 strains, but 1 mg/ml in DJ-26 strain. The optimum temperature and pH were $30^{\circ}C$ and 7.0, respectively, for all the strains. On the basis of the results which the strain of DJ-26 showed the highest degradability of the Aroclor as well as the highest growth rate under the optimum environmental conditions, the bacterial isolate identified as Pseudomonas sp. was found to be a strain usable for treatment of the toxic and recalcitrant chemical pollutants, such as polychlorinated aromatic hydrocarbons.

• Applied Biological Chemistry
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• 제48권3호
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• pp.296-300
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• 2005

Among the root colonizing and plant growth promoting bacteria isolated from the bacterial wilt suppressive soil, five strains were detected to produce siderophores by CAS agar assay. The most effective isolate, TS3-7 strain induced significant suppression of bacterial wilt disease in tomato and pepper plants. Seed treatment followed by soil drench application with this strain resulted in over 80% reduction of bacterial wilt disease compared with the control. Significant disease suppression by TS3-7 strain was related to the production of siderophore. Besides iron competition, induction of resistance of the host plant with siderophore was suggested to be another mode of action that suppress bacterial wilt, based on the lack of direct antibiosis against pathogen in vitro. According to Bergey's Manual of Systemic Bacteriology and 16S rDNA sequence data, TS3-7 stain was identified as Pseudomonas sp. TS3-7.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.48-55
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• 2004

Six strains of an obligate predatory bdellovibrio isolate that preys on Burkholderia glumae in rice paddy field water and rhizosphere soil, were identified and characterized. The numbers of Bdellovibrio cells varied from $3.2{\times}10^3$ to $9.2{\times}10^3$ plaque-forming unit/g after enrichment in cells of B. glumae. Prey range tests with six Bdellovibrio strains and 17 prey strains of rice-pathogenic, antibiosis-related, or nitrogen-fixing bacteria resulted in unique predation patterns in related prey cells. Strain BG282 had the widest prey range on 7 plant pathogenic bacteria among the 17 prey strains tested. However, no predation occurred with strains of Azospirillum brasilense, Paenibacillus polymyxa, Pseudomonas fluorescens, P. putida, and Serratia marcescens that are associated with antibiosis or nitrogen fixation in the rice ecosystem. Identification was confirmed by the presence of typical bdelloplast in the prey cells of B. glumae and by a PCR assay using B. bacteriovorus-specific primers. Furthermore, 16S rDNA sequencing of the six bdellovibrio strains showed a homology range of 97.2% to 99.2% to the type strain of B. bacteriovorus.