• Microbiology and Biotechnology Letters
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• v.14 no.2
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• pp.161-168
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• 1986

A 1.95Kb Sau3Al fragment coding for $\alpha$-amylase from Bacillus amyloliquefaciens was isolated by the shotgun method using Escherichia coli as a host. The genome of Bacillus amyloliquefaciens was partially digested with the restriction endonuclease Sau3Al and joined to plasmid YRp7 cleaved with the restriction endonuclease BamHI. The $\alpha$-amylase gene present in a 1.95Kb insert was stably maintained and expressed in Escherichia coli. The amount of $\alpha$-amylase activity produced by Escherichia coli containing the hybrid plasmid pEA24 was about 65% of the activity produced by the donor Bacillus amyloliquefaciens strain. The properties of $\alpha$-amylase produced by Escherichia coli were very similar to those produced by Bacillus amyloliquefaciens as based on optimum temperature, pH, and effect of CaCl$_2$ concentration. About 70% of the $\alpha$-amylase produced by Escherichia coli was localized in the periplasmic space, whereas the remaining enzyme was localized in the inner part of the cell.

• Journal of Ginseng Research
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• v.5 no.1
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• pp.65-72
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• 1981

In this experiment, observations were made on the effects of ginseng saponin, one of the major components of Korean ginseng (Panax ginseng, C. A. Meyer) root, on the membranes of microorganism (E. coli K-12), the concentration of intracelluar and extracellular cycle AMP therein, and uptake of U-14C-glucose. When the E. coli were grown on media containing 0.1% ginseng saponin, the growth was faster than for that of the control by about 30 minutes. The lysis of E. coli grown on the ginseng saponin medium increased to about double that of the control in the stationary phase. And the amount of protein and lipopolysaccharides in the outer cell meberances increased 25% and 80% respectively in comparison with the control. By electron microscope observation, it was shown that the periplasmic region of the E. coli grown on the ginseng saponin medium was widened it was observed that the cellular cyclic AMP content of the E. coli increased significantly to the hightest levels between the late exponential phase and early stationary phase. The total cyclic AMP content of E. coli grown on the ginseng saponin medium decreased about 50% when compared to that of the control.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.261-265
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• 2011

The sterilization effects of atmospheric pressure plasma with the mixture of argon and oxygen were analyzed. The plasma reactor with the shape of dielectric barrier discharge produced the uniform distribution of glow discharge and generated ozone gas effectively according to the various process parameters. The sterilization for E. coli was affected by power, oxygen ratio in the mixture gas, treatment time and distance between reactor and sample. The concentration of ozone was a major source for the sterilization of E. coli, which was enhanced by the increase of power and oxygen ratio. In this study, the effect of atmospheric pressure plasma treatment for the sterilization was confirmed and its result can deliver the atmospheric pressure plasma treatment as the novel sterilization method instead of conventional methods.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.982-995
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• 2020

A putative multidrug efflux gene, yddA, was cloned from the Escherichia coli K-12 strain. A drug-sensitive strain of E. coli missing the main multidrug efflux pump AcrB was constructed as a host and the yddA gene was knocked out in wild-type (WT) and drug-sensitive E. coliΔacrB to study the yddA function. Sensitivity to different substrates of WT E.coli, E. coliΔyddA, E. coliΔacrB and E. coliΔacrBΔyddA strains was compared with minimal inhibitory concentration (MIC) assays and fluorescence tests. MIC assay and fluorescence test results showed that YddA protein was a multidrug efflux pump that exported multiple substrates. Three inhibitors, ortho-vanadate, carbonyl cyanide m-chlorophenylhydrazone (CCCP), and reserpine, were used in fluorescence tests. Ortho-vanadate and reserpine significantly inhibited the efflux and increased accumulation of ethidium bromide and norfloxacin, while CCCP had no significant effect on YddA-regulated efflux. The results indicated that YddA relies on energy released from ATP hydrolysis to transfer the substrates and YddA is an ABC-type multidrug exporter. Functional study of unknown ATP-binding cassette (ABC) superfamily transporters in the model organism E. coli is conducive to discovering new multidrug resistance-reversal targets and providing references for studying other ABC proteins of unknown function.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1179-1188
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• 2023

Escherichia coli, particularly multidrug-resistant (MDR) strains, is a serious cause of healthcare-associated infections. Development of novel antimicrobial agents or restoration of drug efficiency is required to treat MDR bacteria, and the use of natural products to solve this problem is promising. We investigated the antimicrobial activity of dried green coffee (DGC) beans, coffee pulp (CP), and arabica leaf (AL) crude extracts against 28 isolated MDR E. coli strains and restoration of ampicillin (AMP) efficiency with a combination test. DGC, CP, and AL extracts were effective against all 28 strains, with a minimum inhibitory concentration (MIC) of 12.5-50 mg/ml and minimum bactericidal concentration of 25-100 mg/ml. The CP-AMP combination was more effective than CP or AMP alone, with a fractional inhibitory concentration index value of 0.01. In the combination, the MIC of CP was 0.2 mg/ml (compared to 25 mg/ml of CP alone) and that of AMP was 0.1 mg/ml (compared to 50 mg/ml of AMP alone), or a 125-fold and 500-fold reduction, respectively, against 13-drug resistant MDR E. coli strains. Time-kill kinetics showed that the bactericidal effect of the CP-AMP combination occurred within 3 h through disruption of membrane permeability and biofilm eradication, as verified by scanning electron microscopy. This is the first report indicating that CP-AMP combination therapy could be employed to treat MDR E. coli by repurposing AMP.

• Applied Biological Chemistry
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• v.35 no.4
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• pp.294-299
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• 1992

In order to examine the effect of $TiO_2$ on photosterilization of microorganism. Proper content of $TiO_2$, illumination time, wave length specificity and cell concentration were investigated for photosterilization of E. coli, B. subtilis and S. cerevisiae. The amount of $TiO_2$ for photosterilization of E. coli was effective in the range of $5{\sim}20\;mg%$. The sterilization time was reduced when the low wave length below 400 nth was not cut off by glass, but the catarizing effect of $TiO_2$ was similar to overall wave length. The photosterilization effects by $TiO_2$ addition was recognized among S. cerevisiae, E. coli and B. subtilis in that order. The photosterilization time of S. cerevisiae was considerably reduced at $10^4/ml$ cell concentration compared to $10^5/ml$.

• Journal of Food Hygiene and Safety
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• v.15 no.1
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• pp.55-59
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• 2000

In order to develop a antimicrobial agent, dried bamboo trunk was extracted by high temperature suction and then antimicrobial activities against Staphylococcus aureus ATCC 2825 and Escherichia coli DH 5$\alpha$ were investigated as compared with tea tree oil and BHA. The minimal inhibitory concentrationo(MIC) of the extracted substance against microorganisms were also examined. The results are as follows: 1. By disc diffusion method, BHA showed the strongest antimicrobial activity on Gram-positive bacteria such as S. aureus ATCC 2825 but bamboo essential oil showed the strongest antimicrobial activity on Gram-negative bacteria such as E. coli DH 5$\alpha$. 2. By broth dilution method, the minimum inhibitory concentration of the BHA, tea tree oil and bamboo oil were not detected against S. aureus ATCC 2825(MIC, 6.0 $\mu$l/ ml) and E. coli DH 5$\alpha$(MIC, 6.0 $\mu$l/ ml)

• Journal of Environmental Health Sciences
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• v.40 no.3
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• pp.225-233
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• 2014

Objective: This study was performed in order to investigate the distribution of antibiotic resistant E. coli and water quality in waterscape facilities. Methods: Nine waterscape facilities were selected and classified into three types: ground, wall and general fountain. The items analyzed in this study were pH, turbidity, $KMnO_4$ consumption, total colony, total coliforms, fecal coliforms and E. coli. Additionally, an antibiotic resistance test on E. coli was performed. Results: There were no sampling sites that exceeded the permitted limits of water quality, but the concentration of pollutants was high at the beginning operation in June. Moreover, concentration of turbidity, $KMnO_4$ consumption and total colony were higher in ground fountains than in wall and general fountains. Five species of antibiotic resistant E. coli were detected from three sampling sites. Conclusions: The waterscape facilities were significantly contaminated with water microorganisms, especially total colony, total coliforms and fecal coliforms. Disinfection and filtration systems to remove pollutants should be installed for safe waterscape facilities.

• BMB Reports
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• v.30 no.1
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• pp.80-84
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• 1997

The synthesis and secretion of human angiogenin in E. coli by the natural leader sequence has been studied. We constructed a recombinant plasmid containing human angiogenin cDNA which encompassed all the coding region including leader sequence required for secretion. The recombinant plasmid was introduced into a suitable E. coli host. The angiogenin was detected in the culture medium and periplasm upon the induction of gene expression. The molecular weight of the secreted angiogenin was identical to that of authentic angiogenin purfied from human plasma when estimated by SDS-PAGE and immunoblotting. showing that the natural leader sequence was recognized and processed by the secretion machinery of E. coli. The angiogenin concentration in the culture medium reached a maximum within 2 h when expressed at $37^{\circ}C$ with 0.02~2 mM IPTG. In contrast, the expression level increased gradually over time up to 11 h at $23^{\circ}C$ with 0.002~2 mM IPTG and at $37^{\circ}C$ with 0.002 mM IPTG.

• Biomedical Science Letters
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• v.10 no.3
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• pp.293-298
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• 2004

This study was performed to compare the growth rates, cellular fatty acid compositions and morphology by using electron microscope of Escherichia coli (E. coli) grown in various conditions including different concentrations of phenol, CdCl₂ and HgCl₂. Ninety eight E. coli strains were isolated from Naktong river and human feces. The content of unsaturated fatty acids, especially 16:1ω7c and 18:1ωc increased as the concentration of phenol and CdCl₂ increased. The content of unsaturated fatty acid increased up to 50 ppb of HgCl₂, but decreased at 75 ppb of HgCl₂. There were more unsaturated fatty acids than saturated fatty acid in the presence of toxic substances. However, the ration was reversed when the affected E. coli was transferred to toxic substance free fresh trypticase soy broth medium. Also, by using transmission electron microscope these cells were observed to various morphological deformation by heavy metals and their deposition on the surface. From these results, we suggested that the changes of major fatty acids composition and morphology of E. coli may be considered to indicate contaminated levels of heavy metals or organic solvents. The information presented here may be useful in predicting effects of heavy-metal and organic solvent contamination in streams and provides a basis for further studies of metal or organic solvent effects on microbial communities.