• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.30-35
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• 1993

Clp is a relatively abundant ATP-dependent protease found in E. coli. Its specific activity was proportional to the concentration of the limiting amount of Clp A and an excess amount of Clp P, and vice versa. Clp A has an intrinsic ATPase activity that is stimulated by casein, and contains a second site for binding A TP, in addition to the ATPase site. The modification of sulfhydryl groups in Clp A with reagents which have bulky groups such as N-phenylmaleimide led to nullifying both ATPase and protease activity. The same sites were modified by sulfhydryl reagents. It seems that the sulfhydryl groups of Clp A are not directly involved in catalysis. Since non-hydrolyzable analogs of ATP do not activate Clp, ATP hydrolysis may be essential for the proteolytic activity of Clp protease. Clp A and Clp P did not associate in the absence of nucleotide. The results suggest that the activity of the proteolytic component, Clp P, is regulated by the A TP-dependent cycling of Clp A between the activator form and the non-activator form.

• Korean Journal of Microbiology
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• v.23 no.2
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• pp.107-114
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• 1985

In order to use for recipient strains of RP4:Mu cts, 5 strainsof Rhizobium were selected among 32 strains, which were isolated and identified in this study. Hybrid plasmin RP4::Mu cts, which, is temperature sensitive and confers resistance to ampicillin, kanamycin and tetracycline was transfered by conjugation from E. coli to other atrains of C. coli and the symbiotic nitrogen fixer, Rhizobium leguminosarum. Transfer frequencies of RP4::Mu cts plasmid from E. coli to Rhizobium were about $10^{-8}-10^{-7}$ in LB agar and YMA media. The transconjugants were confirmed by demonstrating that the drug-resistant and temperature-sensitive clones isolated were drug-resistant and temperature-sensitive clones isolated were capable of releasing phage and forming plaques. The plaque-forming units of transconjugants were about $10^2\;to\;10^3$. Stability test of RP4::Mucts in Rhizobium represented that most of the transconjugants had drug resistance and produce phage Mu cts.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.835-839
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• 2011

The characteristics of torch-type atmospheric pressure plasma and its sterilization effects have been analyzed. The length of plasma flame was varied with the level of applied voltage and the mixture gases composed of argon and oxygen. The effect of plasma flame on the temperature increase of surface treated was limited to $43^{\circ}C$ as a maximum temperature under exposing time of 10 min. The sterilization for E. coli was strongly affected by the applied voltage, the oxygen ratio in the mixture gas and the treatment time. At a high concentration of ozone, the increase of treatment time under the direct contact with plasma flame yields to maximize the effect of the sterilization on E. coli.

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.360-363
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• 2010

To enhance the expression and secretion of pediocin PA-1 from heterologous bacterial hosts, the promoter and deduced signal sequence (PS) of an $\alpha$-amylase gene from a Bifidobacterium adolescentis strain was fused with pediocin PA-1 structural and immunity genes (AB) and the resulting functions were evaluated in Escherichia coli. Two recombinant PCR products were created-one with just the deduced signal sequence and one with the sequence plus the Ser and Thr sequences that are the next two amino acids of the signal sequence. These two products, the PSAB (---AQA::KYY---) and PSABST (---AQA$\underline{ST}$::KYY---), respectively, were inserted into a TA cloning vector (yT&A) and named pPSAB, which was previously reported, and pPSABST. The two recombinant plasmid DNAs were transferred into E. coli JM109 and the transformants displayed antimicrobial activity, where the activity of E. coli JM109 (pPSAB) was stronger than that of E. coli JM109 (pPSABST), indicating that the ST amino acid residues were not necessary for secretion and might have even decreased the antimicrobial activity of recombinant pediocin PA-1.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.578-583
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• 2003

The desulfurization genes (dszABC) were cloned from Gordonia nitida. Nucleotide sequences similarity between the dszABC genes of G. nitida and those of Rhodococcus rhodochrous IGTS8 was 89%. The similarities of deduced amino acids between the two were 86% for DszA, 86% for DszB, and 90% for DszC. The G. nitida dszABC genes were expressed in several different Escherichia coli strains under an inducible trc promoter. Cultivation of these metabolically engineered E. coli strains in the presence of 0.2 mM dibenzothiophene (DBT) allowed the conversion of DBT to 2-hydroxybiphenyl (2-HBP), which is the final metabolite of the sulfur-specific desulfurization pathway. The maximum conversion of DBT to 2-HBP was 16% in 60 h. Recombinant E. coli was applied for the deep desulfurization of diesel oil supplemented into the medium at 5% (v/v). Sulfur content in diesel oil was decreased from 250 mg sulfur/1 to 212.5 mg sulfur/1, resulting in the removal of 15% of sulfur in diesel oil in 60 h.

• Journal of Microbiology and Biotechnology
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• v.17 no.2
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• pp.244-252
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• 2007

Escherichia coli has a PhoR-PhoB two-component regulatory system to detect and respond to the changes of environmental phosphate concentration. For the E. coli W3110 strain growing under phosphate-limiting condition, the changes of global gene expression levels were investigated by using DNA microarray analysis. The expression levels of some genes that are involved in phosphate metabolism were increased as phosphate became limited, whereas those of the genes involved in ribosomal protein or amino acid metabolism were decreased, owing to the stationary phase response. The upregulated genes could be divided into temporarily and permanently inducible genes by phosphate starvation. At the peak point showing the highest expression levels of the phoB and phoR genes under phosphate-limiting condition, the phoB- and/or phoR-dependent regulatory mechanisms were investigated in detail by comparing the gene expression levels among the wild-type and phoB and/or phoR mutant strains. Overall, the phoB mutation was epistatic over the phoR mutation. It was found that PhoBR and PhoB were responsible for the upregulation of the phosphonate or glycerol phosphate metabolism and high-affinity phosphate transport system, respectively. These results show the complex regulation by the PhoR-PhoB two-component regulatory system in E. coli.

• Journal of Microbiology and Biotechnology
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• v.22 no.2
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• pp.234-238
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• 2012

Recombinant Escherichia coli displaying organophosphorus hydrolase (OPH) was used to overcome the diffusion barrier limitation of organophosphorus pesticides. A new anchor system derived from the N-terminal domain of ice-nucleation protein from Pseudomonas syringae InaV (InaV-N) was used to display OPH onto the surface. The designed sequence was cloned in the vector pET-28a(+) and then was expressed in E. coli. Tracing of the expression location of the recombinant protein using SDS-PAGE showed the presentation of OPH by InaV-N on the outer membrane, and the ability of recombinant E. coli to utilize diazinon as the sole source of energy, without growth inhibition, indicated its significant activity. The location of OPH was detected by comparing the activity of the outer membrane fraction with the inner membrane and cytoplasm fractions. Studies revealed that recombinant E. coli can degrade 50% of 2 mM chlorpyrifos in 2 min. It can be concluded that InaV-N can be used efficiently to display foreign functional protein, and these results highlight the high potential of an engineered bacterium to be used in bioremediation of pesticide-contaminated sources in the environment.

• Journal of Veterinary Clinics
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• v.33 no.2
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• pp.142-144
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• 2016

We report a case of Escherichia coli septicemia in a 6-year-old male bottlenose dolphin (Tursiops truncatus). Gross lesions included turbid reddish yellow ascites, fibrous adhesions of rectum and peritoneum, multifocal mucosal ulcers of rectum, and systemic petechiae. Multifocal necrosis with bacterial colonies was observed histologically in mucosal membrane of rectum and anus, and also in caudal mesenteric lymph node, inguinal lymph node, tracheobronchial lymph node, tonsil, spleen, liver, and lung. E. coli was isolated in pure culture from multiple organs including blood, spleen, mesenteric lymph node, liver, lung, and ascites. The E. coli was serotype O25. This case was diagnosed as a septicemia caused by E. coli serotype O25 associated with proctitis.

• Korean Journal of Veterinary Service
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• v.32 no.1
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• pp.93-102
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• 2009

In this study, antimicrobial resistance of E. coli isolated from domestic beef on sale in Busan and Gyeongnam province was investigated from March to October 2008. A total of 400 beef samples were collected for the monitoring of antimicrobial resistance, and 39 (9.8%) strains of E. coli were isolated. Antimicrobial resistance test was carried out by agar disc diffusion method with 17 antimicrobials. In general, E. coli isolates showed the highest antimicrobial resistance to tetracycline (85.3%), followed by doxycycline (76.5%), streptomycin (61.8%) and sulfamethoxazole/trimethoprim (61.8%). Then they showed higher resistance to several antimicrobials like kanamycin and neomycin (55.9%). However, They had low antimicrobial resistance to amikacin (8.8%), amoxicillin/clavulanic acid (2.9%). Of 39 isolates, 31 (79.5%) were resistant to more than 2 antimicrobials. Among 17 antimicrobials examined, tetracyclines were the most resistant, followed by aminoglycosides, sulfonamides. The resistance was seemed to be correlated to amounts of antimicrobial use. In the result of this study, we suggest that there be need to regulate the abuse of antimicrobial on food-producing animals in Korea because the concern on antimicrobial resistant is gradually increased worldwide.

• Korean Journal of Veterinary Research
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• v.21 no.1
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• pp.33-40
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• 1981

In order to clarify the morphological changes in the mammary glands of cows affected with coliform (Escherichia coli) mastitis, histopathological observations were undertaken on the mastitis of the lactating rabbits which was experimentally induced with E. coli or its endotoxin isolated from cases of acute and chronic matitis in dairy cattle. In the bacterial suspension-infused groups the affected quarters of udder showed cloudy swelling, hyperemia and hemorrhage to local necrosis and firmness. The microscopic findings of early stage of the mastitis were appearance of large numbers of heterophils in the glandular lumina and ducts accompanied by degeneration, necrosis and desquamation of epithelial cells, and also infiltration of heterophils, hemorrhage and edema in the interstitial tissue, and destruction of alveoli. Later, proliferation of firoblasts, plasma cells, lymphocytes, eosinophils and histiocytes appeared in the glandular tissue and necrotic foci of glandular tissue were surrounded by highly proliferated connective tissue. Granuloma-like inflammatory changes could be observed in the glandular tissue on the 7th days after infusion. The inflammatory response in the group infused with E. coli strain isolated from the natural case of acute mastitis was rapid and severe as compared with that of chronic mastitis. In the endotoxin-infused group the morphological changes were similiar to those of the bacterial suspension-infused groups.