• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.672-677
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• 2005

The standard reference collection of strains for E. coli, the ECOR collection, was analyzed by a genome-based typing method. Seventy-one ECOR strains were subjected to repetitive extragenic palindromic PCR genome fingerprinting with BOX primers (BOX-PCR). Using a similarity value of 0.8 or more after cluster analysis of BOX-PCR fingerprinting patterns to define the same genotypes, we identified 28 genotypes in the ECOR collection. Shannon's entropy-based diversity index was 3.07, and the incident-based coverage estimator indicated potentially 420 genotypes among E. coli populations. Chi-square test of goodness-of-fit showed statistically significant association between the genotypes defined by BOX-PCR fingerprinting and the groups previously defined by multi-locus enzyme electrophoresis. This study suggests that the diversification of E. coli strains in natural populations is actively ongoing, and rep-PCR fingerprinting is a convenient and reliable method to type E. coli strains for the purposes ranging from ecology to quarantine.ine.

• Molecules and Cells
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• 제25권3호
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• pp.446-451
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• 2008

We assessed heterologous protein expression in 64 strains obtained from the Escherichia coli Reference (ECOR) collection, a collection representing diverse natural E. coli populations. A plasmid generating a glutathione S-transferase and plant carbonic anhydrase fusion protein (GST-CA) under the control of the tac promoter was introduced into the ECOR strains, and the quantity of the fusion protein was determined by SDS-PAGE. The foreign protein was generated at various levels, from very high (40 strains, high producers) to very low (six strains, low producers). Immunoblotting showed that the high producers expressed approximately 250-500 times more GST-CA protein than the low producers. The results of semi-quantitative RT-PCR showed that the low producers generated mRNA levels comparable to those of the high producers, thereby suggesting that, at least in this case, inefficient translation is a major cause of the low production. We introduced a different plasmid, which expressed a maltose binding protein and plant guanylate kinase fusion protein (MBP-GK) into the six low producers. Interestingly, five of these expressed MBP-GK at very high levels. Thus, we conclude that the production of a particular protein from an expression vector can vary considerably, depending on the host strain. Strains in the ECOR collection could function as useful alternative hosts when a desired level of protein expression is not obtained from commonly used strains, such as E. coli K12 or B derivatives.

• 해양환경안전학회지
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• 제19권3호
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• pp.285-289
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• 2013

The coastal area of Republic of Korea is very clean compared to other countries. In this reason, west coastal area of our country is a good place for breeding up a fish such as shrimp. In winter season, the heating system is required for preventing shrimp death caused by freezing in the farm. The heater in the heating system for fishery's farm is operated very severe combating corrosion due to high accumulation by feeding material and high temperature in heated sea water. Almost all manufactured heaters of STS 316L and Ti material are scrapped every year due to heavy corrosion such a general and crevice corrosion. For comparing the general and galvanic corrosion in new heater material, the test material of Zirconium (Zr), Titanium (Ti) and STS 316L are tested by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), current density-time methods and microscopic examination in a 3.5% NaCl solution. The corrosion potential (Ecor) measured by potentiodynamic polarization for Zr, Ti and STS 316L reveals -198, -250 and -450mV, corrosion current density 0.5, 2.5 and $6.5{\mu}A/cm^2$ respectively. The film resistance measured by EIS are Zr 63,000, Ti 39,700 and 316L $3,150{\Omega}$, and the current of Zr-Ti couple is $0.03{\mu}A$, whereas Zr-316L SS is $0.1{\mu}A$. According to the result of this experiment in 3.5% NaCl solution, Zr is excellent corrosion resistance material than Ti and STS 316L.

• 한국미생물·생명공학회지
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• 제29권1호
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• pp.18-24
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• 2001

누에 핵다각체병 바이러스의 gp64 프로모터를 이용한 transient 발현 벡터를 제작하기 위해서 gp64 유전자의 구조를 분석하였다. Southern blotting 분석을 통해 genome DNA에서 gp64 유전자를 탐색하기 gp64 구조유전자를 포함하는 2,277 nucleotide의 염기를 분석하였으며 gp64의 early, late 프로모터 발현을 조절하는 인자들을 확인하였다. gp64프로모터를 이용한 transient 발현 벡터를 제작하고 외래유전자로써 lacZ 유전자를 Bm5 세포주에서 transient 발현시켰다. 세포주 내에 도입된 플라스미드 DNA의 안정성을 확인하였으며, gp64 프로모터의 외래유전자 발현성 여부를 조사하기 위하여 gp64 프로모터 하에 laxZ 유전자를 가지는 재조합 바이러스를 제작하고 $\beta$-galactosidase in 냐셔 staining을 수행한 결과 전체적인 발현량은 매우 약한 것으로 판단되었다. BmNPV-K1의 gp64 프로모터를 이용한 벡터는 더욱 민감한 표지 유전자를 발현시켜 재조합 바이러스의 분리에 이용하거나 숙주세포에 독성을 보이는 유전자 산물의 소량 발현에 더욱 유용할 것으로 판단된다.