• Journal of Microbiology
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• 제38권1호
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• pp.36-39
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• 2000

Toxic hexavalent chromium, Cr(VI), was reduced to a less toxic trivalent chromium form by E. coli ATCC 33456. The suitable electron donor for Cr(VI) reduction was glucose. E. coli ATCC 33456 was more resistant to metal cations than other reported Cr(VI) reducing microorganisms. Cell growth was inhibited by the presence of Cr(VI) in a liquid medium and Cr(VI) reduction accompanied cell growth. With a hydraulic retention time of 20 h, Cr(VI) reducing efficiency was 100% to 84% when Cr(VI) concentration in the influent was in the range of 10 to 40 mg L$\^$-1/. Specific rate of Cr(VI) reduction was 2.41 mg Cr(VI) g DCW$\^$-1/ h$\^$-1/ when 40 mg L$\^$-1/ of Cr(VI) influent was used. This result suggested the potential application of E. coli ATCC 33456 for the detoxification of Cr(VI) in Cr(VI) contaminated wastewater.

• 한국미생물·생명공학회지
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• 제21권1호
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• pp.30-35
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• 1993

E.coli에서 발견된 ATP-dependent 효소인 Clp효소 중에서 Clp A의 ATPase 활성에 대한 영향을 검토하였다. Clp효소의 limiting amount으로 나타난 specific 활성은 일정하게 증가하는 효소의존성을 보였다. ATPase 활성을 나타내고 있는 ClP A는 casein에 의하여 활성화되어지며 2분자의 ATP가 결합하고 ATPase 활성을 나타내기 위한 ATP의 분해는 Clp효소의 단백질 분해 활성에 필요하다.

• Biomolecules & Therapeutics
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• 제2권2호
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• pp.120-125
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• 1994

We obtained the total protein antibodies of Saccharomyces cerevisiae KCTC 1720 and Escherichia coli K-12 from the rabbit and the guinea pig to determine the host-derived proteins which may be remained in biotechnological products. The protein concentration of rabbit antibodies was 4.05 mg/mι in the case of yeast, 7.14 mg/mι in the case of E. coli and that of guinea pig antibodies was 1.90 mg/mι in the case of yeast, 7.17 mg/mι in the case of E. coli, respectively. To determine remained host-derived proteins in biotechnological products which produced by the hosts, S. cerevisiae or E. coli, we used a sandwich enzyme linked immunosorbent assay method in 96 well microplate. When the method applied to determine the remained host-derived proteins in commercial biotechnological products, it detected less than 3.5 ng/vial in human growth hormone, less than 1 ng/vial in hepatitis B vaccine and interferon-${\gamma}$ and 2~23 ng/vial in interferon-$\alpha$. The method can be used to determine the remained host-derived protein in biotechnological products.

• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.137-142
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• 2015

Trimethoprim-sulfamethoxazole (TMP-SMX) has been used for the treatment of urinary tract infections, but increasing resistance to TMP-SMX has been reported. In this study, we analyzed TMP-SMX resistance genes and their relatedness with integrons and insertion sequence common regions (ISCRs) in uropathogenic gram-negative bacilli. Consecutive nonduplicate TMP-SMX nonsusceptible clinical isolates of E. coli, K. pneumoniae, Acinetobacter spp., and P. aeruginosa were collected from urine. The minimal inhibitory concentration was determined by Etest. TMP-SMX resistance genes (sul and dfr), integrons, and ISCRs were analyzed by PCR and sequencing. A total of 45 E. coli (37.8%), 15 K. pneumoniae (18.5%), 12 Acinetobacter spp. (70.6%), and 9 Pseudomonas aeruginosa (30.0%) isolates were found to be resistant to TMP-SMX. Their MICs were all over 640. In E. coli and K. pneumoniae, sul1 and dfr genes were highly prevalent in relation with integron1. The sul3 gene was detected in E. coli. However, in P. aeruginosa and Acinetobacter spp., only sul1 was prevalent in relation with class 1 integron; however, dfr was not detected and sul2 was less prevalent than in Enterobacteriaceae. ISCR1 and/or ISCR2 were detected in E. coli, K. pneumoniae, and Acinetobacter spp. but the relatedness with TMP-SMX resistance genes was not prominent. ISCR14 was detected in six isolates of E. coli. In conclusion, resistance mechanisms for TMP-SMX were different between Enterobacteriaceae and glucose non-fermenting gram-negative bacilli. Class 1 integron was widely disseminated in uropathogenic gram-negative baciili, so the adoption of prudent use of antimicrobial agents and the establishment of a surveillance system are needed.

• BMB Reports
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• 제41권8호
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• pp.568-574
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• 2008

Antisense RNA molecules are powerful tools for controlling the expression of specific genes but their use in prokaryotes has been limited by their unpredictable antisense effectiveness. Moreover, appreciation of the molecular mechanisms associated with silencing in bacteria is still restricted. Here we report our attempts to define an effective antisense strategy in E. coli, and to dissect the observed silencing process. Antisense constructs complementary to different regions of lacZ were investigated, and silencing was observed exclusively upon expression of antisense RNA hybridising the 5'UTR of lac messenger. The level of lacZ mRNA was reduced upon expression of this antisense construct, and the silencing competence was found to be closely associated with its stability. These observations may help in the design of antisense molecules directed against prokaryotic genes.

• 한국식품조리과학회지
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• 제14권1호
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• pp.9-15
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• 1998

저농도의 clove(0~0.5%, w/v)를 함유한 tryptic soy broth(TSB)에 E. coli 0157:H7을 $10^{*}$ 5-$10^{*}$ 7 cells/ml되게 접종하여 clove가 E. coli의 증식과 생존에 미치는 효과를 이 세균의 최적온도($35^{\circ}C$)와 저온(-20, $5^{\circ}C$) 및 고온(50, $55^{\circ}C$)에서 검토하였다. $35^{\circ}C$에서의 E. coli의 증식은 0.1%의 clove 농도에서 배양초기부터 빠른 속도로 종식하였으나 0.3%에서는 약간의 유도기를 거친 후에 증식이 시작되었고 0.5%에서는 저장기간 중생균수가 감소하였다. Clove를 함유한 TSB에 $10^{*}$ 6~$10^{*}$ 7 cells/ml가 되게 E. coli를 접종하여 32일간 저온저장(-20, $5^{\circ}C$)하였을 때 E. coli에 대한 생존억제는 냉장에서 clove의 농도가 높을수록, 저장기간이 길어질수록 뚜렷해졌으며 0.3%와 0.4%에서는 각각 저장 32일, 24일에 사멸하였다. -2$0^{\circ}C$에서 동결저장한 경우에는 저장초기의 4일간 2.9~4.07 log cycle의 급격한 감소를 나타내었으며 이후부터 32일간 저장하는 동안 1.0~2.1 log cycle 감소하였고 첨가한 clove의 농도차이 에 따른 생존억제효과는 약간의 차이 에 불과하였다. $50^{\circ}C$에 저장한 E. coli는 clove농도 0, 0.1, 0.2, 0.3, 0.4%에서 D-value는 각각 105.26, 22.47, 13.76, 11.14, 10.17분이었으며 $55^{\circ}C$에서 D-value는 clove의 농도 0, 0.1, 0.2, 0.3, 0.4%에서 각각 10.75, 8.95, 7.40, 5.96, 4.96분이었다. Clove에 의한 생존억제작용은 $55^{\circ}C$에 비하여 $50^{\circ}C$에서 뚜렷한 효과를 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제28권3호
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• pp.439-447
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• 2018

The aromatic compound p-hydroxybenzoate (PHBA) is an important material with multiple applications, including as a building block of liquid crystal polymers in chemical industries. The cytochrome P450 (CYP) enzymes are beneficial monooxygenases for the synthesis of chemicals, and CYP53A15 from fungus Cochliobolus lunatus is capable of executing the hydroxylation from benzoate to PHBA. Here, we constructed a system for the bioconversion of benzoate to PHBA in Escherichia coli cells coexpressing CYP53A15 and human NADPH-P450 oxidoreductase (CPR) genes as a redox partner. For suitable coexpression of CYP53A15 and CPR, we originally constructed five plasmids in which we replaced the N-terminal transmembrane region of CYP53A15 with a portion of the N-terminus of various mammalian P450s. PHBA productivity was the greatest when CYP53A15 expression was induced at $20^{\circ}C$ in $2{\times}YT$ medium in host E. coli strain ${\Delta}gcvR$ transformed with an N-terminal transmembrane region of rabbit CYP2C3. By optimizing each reaction condition (reaction temperature, substrate concentration, reaction time, and E. coli cell concentration), we achieved 90% whole-cell conversion of benzoate. Our data demonstrate that the described novel E. coli bioconversion system is a more efficient tool for PHBA production from benzoate than the previously described yeast system.

• KSBB Journal
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• 제13권1호
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• pp.96-100
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• 1998

두 개의 프로모터 (trc와 Pp)를 Alcaligenes eutrophus에서 유래된 PHA 오페론에 삽입하여 재조합 대장균에서 분자량이 큰 polyhydroxybutyrate (PHB)를 얻고자 하였다. 두 개의 프로모터는 hydroxybutyric CoA와 PHA 중합반응의 유전자 발현을 각각 독립적으로 제어하기 위해 설계된 것이다 새로운 합성오페론을 포함한 플라즈미드는 E. coli DH5 $\alpha$ 에 transformation 되어 PHB 생산에 이용되었다. 본 실험의 가설로서 PHA 합성오페론의 IPTG에 의한 유도가 없을 경우 낮은 pHA synthase의 활성이 고분자 중합반응의 개시제 농도를 줄여주어 결과적으로 높은 연결수의 고분자를 생성할 것이라는 모델을 세웠다. 실제로 IPTG의 공급이 없는 발효실험을 통해 평균분자량이 $2.5{\times}10^7$ 인 거대 고분자를 얻을 수 있었다. PHA 생합성에 관여는 효소의 활성 분석으로 3-hydroxybutyric CoA의 중합을 촉매하는 효소인 PHA synthase의 활성을 가지고 In vivo에서 분자량이 제어됨을 확인하였다.

• 대한의생명과학회지
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• 제27권4호
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• pp.323-328
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• 2021

Naegleria fowleri is a free-living amoeba causing primary amoebic encephalitis. In this study, we analyzed how the N-aceytlglucosamine (GlcNAc) and D-galactose affected the interaction between Naegleria fowleri and methicillin-resistant Staphylococcus aureus (MRSA) or Escherichia coli O157:H7, and the interaction with bacteria when monosaccharides were treated with N. fowleri for a longer pre-incubation time. When GlcNAc was treated with N. fowleri for 1 hr, the E. coli association was almost the same as that of the control not treated with GlcNAc until the concentration of GlcNAc was 25 mM. However, the E. coli association was reduced by approximately 91% with 100 mM GlcNAc. E. coli invasion into N. fowleri showed statistical significance only in the group treated with 100 mM GlcNAc. The interaction when treated with galactose showed a very different pattern in the 50 mM galactose group than when treated with GlcNAc. In the MRSA interaction, a statistically significant decrease in association (76.3% by GlcNAc and 88.7% by galactose) and invasion (3.6% by GlcNAc and 9.3% by galactose) was shown by the concentration of two 100 mM monosaccharides. The group treated with monosaccharides at the same time showed almost no difference in all interactions from the group treated with monosaccharides at the same time. Taken together, it suggested that the effect of monosaccharides on the interaction of several Gram-negative or positive bacteria and the evidence that the interaction could be enhanced by longer pre-incubation time.

• 한국환경과학회지
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• 제21권8호
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• pp.901-907
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• 2012

The objective of this study was to evaluate bacteria removal ability of the metallic silver which was baked silver ion impregnated ceramic filter at heating condition. Silver leaking from baked ceramic filter was tested to sustain bacteria removal for a long time. Silver impregnated ceramic filter could remove E. coli completely at $10^{12}$ MPN/100ml to $10^{13}$ MPN/100ml of influent. However, ceramic filter without silver did not remove E. coli completely under the same condition. After baking, the silver impregnated ceramic filter almost didn't leak out the silver ion from filter. Photo of TEM (Transmission Electron Microscopy) showed that absorbed silver ions remained in ceramic filter after baking process and most of silver were less than 10 nm. According to the increase in the amount of silver in the ceramic filter, removal efficiencies of E. coli were increased but turbidity removal was decreased. It can be accounted that increased removal efficiency of E. coli was from disinfection of silver that is in the ceramic filter. Simulated concentrations of bacteria agree well with the observed experimental effluent concentration data. Moreover, first-order decay coefficients increased to 0.0034/min after silver was added in the ceramic filter. Increase of first-order decay coefficient proves that silver-added ceramic filter can remove bacteria easily.