• Journal of Microbiology and Biotechnology
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• 제20권5호
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• pp.908-916
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• 2010

Fullerene-60 nanoparticles were used for studying their effect on the low-density polyethylene (LDPE) biodegradation efficiency of two potential polymer-degrading consortia comprising three bacterial strains each. At a concentration of 0.01% (w/v) in minimal broth lacking dextrose, fullerene did not have any negative influence upon the consortia growth. However, fullerene was found to be detrimental for bacterial growth at higher concentrations (viz., 0.25%, 0.5%, and 1%). Although addition of 0.01% fullerene into the biodegradation assays containing 5mg/ml LDPE subsided growth curves significantly, subsequent analysis of the degraded products revealed an enhanced biodegradation. Fourier transform infrared spectroscopy (FT-IR) revealed breakage and formation of chemical bonds along with the introduction of ${\nu}C$-O frequencies into the hydrocarbon backbone of LDPE. Moreover, simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) revealed a higher number of decomposition steps along with a 1,000-fold decrease in the heat of reactions (${\Delta}H$) in fullerene-assisted biodegraded LDPE, suggesting the probable formation of multiple macromolecular byproducts. This is the first report whereby fullerene-60, which is otherwise considered toxic, has helped to accelerate the polymer biodegradation process of bacterial consortia.

• Archives of Pharmacal Research
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• 제19권5호
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• pp.400-405
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• 1996

In vitro studies were conducted to dertermine the frequency rate of spontaneous resistance to LB20304 and to dertermine whether cross-resistance to other antimicrobial agents develops. In eight strains of bacteria, the frequency of mutation to LB20304 at the concentrations of four and eight times the minimal inhibitory concentration(MIC) ranaged from less than 4.0 ${\times}$ $10^{-10}$ to 2.2 $\{times}$ $10^{-10}$ . These results were similar to those founf for other new fluoroquinolones. THe development of stepwise resistance was determined by repeated subculture in broth in the presence of increasing concentration of the compounds. Exposure of bacteria to increasing concentrations of LB20304 resulted in the selection of organisms with higher MICs. There were 4- to 128-fold increases in the MIC of LB20304 for bacterial strains of Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli and Pseudomonas aeruginosa. However, those strains selected after repeated exposure were well within the susceptibility range for LB20304 except for Pseudomonas aeruginosa. The resistant isolates selected with LB20304 showed cross-resistance when tested against ciprofloxacin and vice versa.

• KSBB Journal
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• 제30권4호
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• pp.161-165
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• 2015

Lactic acid and its derivatives are widely used in the food, pharmaceutical, and cosmetic industries. It is also a major raw material for the production of poly-lactic acid (PLA), a biodegradable and environmentally friendly polymer and a possible alternative to synthetic plastics derived from petroleum. For PLA production by new strains of lactic acid bacteria (LAB), we screened LAB isolates from shellfish. A total of 51 LAB were isolated from 7 types of shellfishes. Lactic acid production of individual isolates was examined using high-performance liquid chromatography using a Chiralpak MA column and an ultraviolet detector. Lactobacillus plantarum T-3 was selected as the most stress-resistant strain, with minimal inhibition concentrations of 1.2 M NaCl, 15% ethanol, and 0.0020% hydrogen peroxide. In a 1 L fermentation experiment, $\small{D}$-lactic acid production of 19.91 g/L fermentation broth was achieved after 9 h cultivation, whereas the maximum production of total lactic acid was 41.37 g/L at 24 h.

• Natural Product Sciences
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• 제13권4호
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• pp.342-346
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• 2007

The antimicrobial activity of the essential oil from Pelargonium graveolens and its effects when it was combined with current antibiotics against antibiotic-resistant strains of Streptococcus pneumoniae were evaluated. The minimal inhibitory concentrations (MICs) of the essential oil fraction and the main components of this plant were determined for two antibiotic-susceptible and two antibiotic-resistant strains of S. pneumoniae using broth microdilution tests. The combined effects of the oil with erythromycin, norfloxacin, or oxacillin were evaluated using a checkerboard microtitre assay. The combination of the oil fraction of P. graveolens, or its main component, together with the antibiotics tested significantly lowered the MICs of the antibiotics against all of the tested strains with fraction inhibiting concentration indices (FICs) ranging from 0.16 to 1.50. In particular, the activity of norfloxacin against all of the tested strains of S. pneumoniae was enhanced significantly by combination with citronellol. In conclusion, the combination of P. graveolens oil with antibiotics could be used to reduce the effective dose of antibiotic and to modulate the resistance of S. pneumoniae strains.

• Food Science and Biotechnology
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• 제15권4호
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• pp.511-515
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• 2006

Antibiotic resistance of foodborne pathogens adapted to garlic (Allium sativum Linn.) was determined in order to understand the relationship between antibiotic resistance and garlic. The Gram (-) strains of Escherichia coli and Salmonella typhimurium and the Gram (+) strains of Bacillus cereus and Staphylococcus aureus were subcultured consecutively in a garlic broth, and the surviving colonies on the agar were selected as the adapted strains. Minimal inhibitory concentrations (MIC) for 15 antibiotics on the adapted strains were determined on Muller-Hinton Infusion agar. Adaptation to 1.3%(v/v) garlic juice increased MIC for vancomycin, aminoglycoside, and erythromycin on B. cereus, and for ampicillin and erythromycin on E. coli O157:H7. MIC of aminoglycosides, chloramphenicol, and vancomycin on the adapted S. aureus increased. The adapted S. typhimurium was more resistant to penicillin and vancomycin than the non-treated strain. The adapted S. typhimurium and S. aureus lost their antibiotic resistance in non-garlic stress conditions. However, the adapted B. cereus was still resistant to erythromycin and vancomycin, and the adapted E. coli was also resistant to erythromycin. Antibacterial garlic might increase the antibiotic resistance of E. coli, B. cereus, S. aureus, and S. typhimurium and this resistance can continue even without the stress of garlic. Therefore, garlic as a food seasoning could influence the resistance of such pathogens to these antibiotics temporarily or permanently.

• 미생물학회지
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• 제40권2호
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• pp.100-103
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• 2004

Inonotus mikadoi IMSNU 32058의 최적 균사생장을 위한 배양학적 특성 및 세포효소 활성의 최적 조건을 조사하였다. 균사 생장을 위한 최적온도는 $27^{\circ}C$였고, 실험한 pH 범위중pH 4.5에서 최적균사 생장을 나타내었다. 사용된 복합배지 중 malt extract media (MEM)와Phellinus igniarius media (PIM)에서 가장 좋은 균사 생장을 나타내었다. 최소배지로써 Czapek-Dox 한천배지를 사용하여 탄소원으로 단당류, 이당류 및 다항류를 침가하였을 때 xylose, raffinose 및 carboxymethyl cellulose (CMC)에서 가장 좋은 생장을 나타내었다. 일반적으로 유기질소원이 무기질소원보다 생장을 더 촉진하였다. 유기질소원으로는 yeast extract, soytone, proteose peptone 및 bacto peptone을 사용하였을 때 균사생육이 우수하였다. 무기질소원으로는 ammonium sulfate를 사용했을 때 균사생육이 촉진되었으며, 가장 우수한 비타민원은 p-aminobenzoic acid (PABA)이었다. MEM 액체(pH 4.5) 배지를 이용하여 $27^{\circ}C$에서 5일간 배양하였을 때, I. mikadoi의 균사외 분비효소 및 균사내 효소의 활성도를 측정하였다. 균사내 분비 효소중 laccase 의 활성도가 다른 효소에 비해 상대적으로 높았다. 균사외 분비 효소도 균사내 분비효소와 마찬가지로 laccase의 활성도가 다른 효소에 비해 상대적으로 높았으며 protease, chitinase 그리고 lipase의 활성도는 낮거나 없었다.

• 생명과학회지
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• 제20권2호
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• pp.269-274
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• 2010

항생제 및 항진균제 개발에 있어 미생물 유래 천연 생리활성물질 분리를 통한 선도물질을 확보하는 일은 매우 중요하며, 신규 물질을 확보하기 위해 꾸준한 연구가 필요할 것으로 사료된다. 따라서 본 연구에서는 천연 항생물질의 개발을 위한 연구의 일환으로 태백산 일대의 토양에서, 인체에 다양한 감염증을 유발하는 효모와 곰팡이에 대하여 강한 항진균 활성을 나타내는 BCNU 2003 균주를 분리하여 항진균 활성 물질의 이용가능성에 대해 연구하였다. BCNU 2003은 계통적으로는 B. amyloliquefaciens와 B. vallismortis의 subcluster에 속하는 균주로 동정되어 Bacillus sp. BCNU 2003으로 명명하였다. 항균물질 분리를 위해 ethyl acetate (EA) 추출물과 펩타이드 추출물로 나누어 그람양성 세균, 그람음성 세균 및 진균에 대한 항균활성을 측정한 결과, EA 추출물이 6종의 인체병원성 진균에 대해 모든 높은 항진균 활성을 나타내었다. 특히 기회성 감염을 유발하는 A. niger, C. albicans 그리고 Sa. cerevisiae에 대해 높은 억제 활성을 나타냈으며, 균배양액에서 낮은 저해율을 보였던 Ep. floccosum에 대해서도 EA 추출물은 높은 활성을 나타내었다. 따라서 다양한 인체 병원성 진균에 대해 넓은 항균스펙트럼을 가지는 Bacillus sp. BCNU 2003 균주의 활성물질 분리를 통해 특정 항균 및 항진균 물질의 대량생산 조건 등의 추가적인 연구를 수행한다면, 인체 감염증을 포함한 광범위한 피부치료제의 응용개발이 가능하리라 사료된다.

• 한국균학회지
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• 제23권2호통권73호
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• pp.153-160
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• 1995

담자균류의 하나인 잔나비걸상 자실체로부터 얻은 수성엑스의 항세균 시험과 항진균 시험을 액체배지 희석법으로 실시하고 naringenin과의 병용시험을 checkerboard assay 법으로 평가하였다. 항세균 시험결과 전반적으로 그람음성균보다 그람양성균에 대해 비교적 양호한 항균력을 나타내었으나 사용된 균주중 그람음성균인 Proteus vulgaris 78615는 MIC가 1.125 mg/ml로 가장 양호한 항균효과를 나타내었다. 11종의 균주에 대해 실시된 항진균 시험결과 Candida albicans, Fusarium spp. 그리고 Trichophyton mentagraphytes의 MIC가 7.5 mg/ml로 다른 균주에 대한 항진균 효과보다 두배 더 강한 효과를 나타내었다. naringenin과의 병용시험에서 Staphylococcus aureus ATCC 25923에 대하여 부분적 상승효과를 나타내었고, Klebsiella pneumoniae ATCC 10031과 Salmonella typhi ATCC 6229 두 균주에서 상가효과가 관찰되었다. 그리고 Bacillus subtilis ATCC 6633을 비롯한 7종의 균주에서 무관효과를 나타내었으며 길항효과는 관찰되지 않았다.

• Journal of Microbiology and Biotechnology
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• 제18권3호
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• pp.477-482
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• 2008

A variety of bacterial strains were isolated from waste disposal sites of Uttaranchal, India, and some from artificially developed soil beds containing maleic anhydride, glucose, and small pieces of polyethylene. Primary screening of isolates was done based on their ability to utilize high- and low-density polyethylenes (HDPE/LDPE) as a primary carbon source. Thereafter, a consortium was developed using potential strains. Furthermore, a biodegradation assay was carried out in 500-ml flasks containing minimal broth (250ml) and HDPE/LDPE at 5mg/ml concentration. After incubation for two weeks, degraded samples were recovered through filtration and subsequent evaporation. Fourier transform infrared spectroscopy (FTIR) and simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) were used to analyze these samples. Results showed that consortium-treated HDPE (considered to be more inert relative to LDPE) was degraded to a greater extent (22.41% weight loss) in comparison with LDPE (21.70% weight loss), whereas, in the case of untreated samples, weight loss was more for LDPE than HDPE (4.5% and 2.5%, respectively) at $400^{\circ}C$. Therefore, this study suggests that polyethylene could be degraded by utilizing microbial consortia in an eco-friendly manner.

• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.791-807
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• 2017

The type II secretion system (T2SS), which transports selected periplasmic proteins across the outer membrane, has rarely been studied in nonpathogens or in organisms classified as Betaproteobacteria. Therefore, we studied Cupriavidus metallidurans (Cme), a facultative chemilithoautotroph. Gel analysis of extracellular proteins revealed no remarkable differences between the wild type and the T2SS mutants. However, enzyme assays revealed that native extracellular alkaline phosphatase is a T2SS substrate, because activity was 10-fold greater for the wild type than a T2SS mutant. In Cme engineered to produce three Ralstonia solanacearum (Rso) exoenzymes, at least 95% of their total activities were extracellular, but unexpectedly high percentages of these exoenzymes remained extracellular in T2SS mutants cultured in rich broth. These conditions appear to permit an alternative secretion process, because neither cell lysis nor periplasmic leakage was observed when Cme produced a Pectobacterium carotovorum exoenzyme, and wild-type Cme cultured in minimal medium secreted 98% of Rso polygalacturonase, but 92% of this exoenzyme remained intracellular in T2SS mutants. We concluded that Cme has a functional T2SS despite lacking any abundant native T2SS substrates. The efficient secretion of three foreign exoenzymes by Cme is remarkable, but so too is the indication of an alternative secretion process in rich culture conditions. When not transiting the T2SS, we suggest that Rso exoenzymes are probably selectively packaged into outer membrane vesicles. Phylogenetic analysis of T2SS proteins supports the existence of at least three T2SS subfamilies, and we propose that Cme, as a representative of the Betaproteobacteria, could become a new useful model system for studying T2SS substrate specificity.