• Food Quality and Culture
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• v.3 no.1
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• pp.34-39
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• 2009

This study assessed the efficacy of aqueous chlorine dioxide ($ClO_2$) and commercial chlorine sanitizer in terms of its ability to eliminate Listeria monocytogenes, Salmonella Typhimurium, and Escherichia coli O157:H7 on radish sprouts (Raphanus sativus L.). Radish sprouts were inoculated with a cocktail containing one each of three strains of three different foodborne pathogens, then treated with distilled water (control) or chemical sanitizers (100 ppm commercial chlorine, and 50, 100, 200 ppm $C1O_2$) for 1, 5, and 10 min at room temperature ($22{\pm}2^{\circ}C$). Populations of S. Typhimurium, E. coli O157:H7 and L. monocytogenes were counted at 4.64, 6.05, and 4.29 log CFU/g, respectively, after inoculation. Treatment with water did not significantly reduce the levels of any of the three foodborne pathogens. The levels of all three pathogens were reduced by treatment with chemical sanitizers; however, the observed levels of reduction of E. coli O157:H7 and L. monocytogenes were not significant as compared with the controls. The levels of the three pathogens were reduced most profoundly when treated for 10 min with 200 ppm of $C1O_2$, and the reduction levels of S. Typhimurium, E. coli O157:H7, and L. monocytogenes were 1.17, 1.63, and 0.96 log CFU/g, respectively. When chemically injured cells were investigated using SPRAB for E. coli O157 :H7 and by selective overlay methods for S. Typhimurium and L. monocytogenes, respectively, it was noted that commercial chlorine sanitizer generated more numbers of injured pathogens than did $C1O_2$. These data indicate that $C1O_2$ treatment may prove useful in reducing the numbers of pathogenic bacteria in radish sprouts.

• Food Science and Biotechnology
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• v.14 no.1
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• pp.164-167
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• 2005

The growth responses of materials extracted from Juniperus virginiana leaves against Bifidobacterium bifidum, B. longum, Clostridium perfringens, Escherichia coli, Lactobacillus acidophilus, L. casei, and Streptococcus mutans were examined using impregnated paper disk agar diffusion. The biologically active constituent isolated from the J. virginiana extracts was characterized as ${\alpha}$-cedrene using various spectroscopic analyses including IR, EI-MS, and NMR. The responses varied according to the dose, chemicals, and bacterial strain tested. Methanol extracts of J. virginiana leaves exhibited a strong and moderate inhibitory activity against C. perfringens and E. coli at 5 mg/disk, respectively. However, in tests conducted with B. bifidum, B. longum, L. acidophilus, L. casei, and S. mutans, the methanol extracts showed no or weak inhibitory response. At 2 mg/disk, a-cedrene strongly inhibited the growth of C. perfringens and moderately inhibited the growth of E. coli and S. mutans, without any adverse effects on the growth of four lactic acid-bacteria. Of the commercially available compounds originating from J. virginiana leaves, cedrol and ${\alpha}$-pinene exhibited strong and moderate growth inhibition against C. perfringens, and ${\alpha}$-copaene revealed moderate growth inhibition against E. coli at 1 mg/disk. Furthermore, cedrol exhibited moderate and weak growth inhibition against S. mutans at 2 and 1 mg/disk, respectively. However, little or no activity was observed for camphene, (+)-2-carene, p-cymene, limonene, linalool, and a-phellandrene against B. bifidum, B. longum, C. perfringens, L. acidophilus, L. casei, and S. mutans at 2 mg/disk. The observed inhibitory activity of the J. virginiana leaf-extracted materials against C. perfringens, E. coli, and S. mutans may be an indication of at least one of the pharmacological actions of the J. virginiana leaf.

• Korean Journal of Veterinary Service
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• v.44 no.4
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• pp.247-256
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• 2021

The recombinant lysozyme-HJL34 proteins were expressed and purified using commercial Escherichia (E.) coli expression system. Stx2e⁺ F18⁺ E. coli, Actinobacillus pleuropneumoniae (APP), Streptococcus (S.) suis, and Clostridium (C.) perfringens strains were isolated from pigs. The minimum inhibitory concentrations (MICs) of the recombinant lysozyme-HJP34 proteins were examined by means of the microtiter plate method, according to the NCCLS recommendations. The possibility of its as the alternatives to antibiotics was tested in piglets. The MICs were determined as 75 ㎍/mL, 300 ㎍/mL, 75 ㎍/mL, 35.5 ㎍/m against Stx2e⁺ F18⁺ E. coli, APP, S. suis, C. perfringens, respectively. A total of 25 piglets were divied 5 groups. The piglets in group A~C were fed with commercial feed and those in groups D, E were fed with commercial feedstuff. All piglets in groups B~E were challenged with virulent Stx2e⁺ F18⁺ E. coli, APP, S. suis strains. Groups C and D were treated with antimicrobial from 24 h after challenge. All piglets in group B died within 3 days after challenge. Among 5 piglets in groups C and D piglets, 80% survived after challenge. Among group E piglets, 60% were alive until the end of this study. Therefore, this study indicates that recombinant lysozyme-HJP34 proteins is a suitable possibility as a feed additive for reduction of diseases by bacterial pathogens in piglet feed.

• Korean Journal of Microbiology
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• v.28 no.2
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• pp.114-119
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• 1990

A yeast chromosomal superkiller gene (SK13) was cloned and expressed in $ski3^{-}$ Saccharomyces cerevisiae strains. The gene was fused to the structural region of E. coli lacZ gene at its C-terminus in a yeast-E. coli shuttle vector, pSR605. The fused gene complemented $ski3^{-}$ strains with SK13 activity and the quantitative level of expression was measured as determined by assaying $\beta$-galactosidase activity. The SDS-polyacrylamide gel electrophoresis and the Western blot analysis of this fused protein showed the immuno-reacted bands with a protein of the estimated molecular size (ca.250Kd).

• Microbiology and Biotechnology Letters
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• v.17 no.2
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• pp.154-159
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• 1989

Chromosomal DNA fragments of Bacillus sp. YA-14 isolated from soil as a potent xylan hydrolyzing bacterium, were ligated to a vector plasmid, pBR322, and used to transfer Escherichia coli HB101 cells. The recombinant plasmid pYDC21 was found to enable the transformants to produce xylanase. pYDC21 was found to contain the 3 kb HindIII fragment originated from the Bacillus sp. YA-14 chromosomal DNA by southern hybridization. The optimum temperature and pH for the reaction of xylanse produced by E. coli (pYDC21) were appeared at 50$_7$C and pH 7.0, respectiveiy. the xylanase enzyme was stable between pH 5.0 and 7.0 and maintained stably up to 4$0^{\circ}C$.

• Korean Journal of Veterinary Research
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• v.43 no.1
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• pp.139-144
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• 2003

A chitinase cDNA named CHT1 was cloned from the hard tick, Haemaphysalis longicornis, and the enzymatic properties of its recombinant proteins were characterized. The CHT1 cDNA encodes 930 amino-acid (aa) residues including a 22 aa putative signal peptide, with the calculated molecular mass of the putative mature protein 104 kDa. The E coli-expressed rCHT1 exhibited weak chitinolytic activity against $4MU-(GlcNAc)_3$. The rCHT1 protein with higher activity was obtained using recombinant Autographa californica multiple nuclear polyhedrosis virus (AcMNPV), which expresses rCHT1 under polyhedrin promoter. These findings suggest that the rCHT1 expressed in baculovirus-mediated Sf 9 cells has a high activity than E coli-expressed rCHT1.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.196-198
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• 2001

The growth retardation of Escherichia coli and Staphylococcus aureus by heat or acid treated leek (Allium tuberosum) extract was observed. Antimicrobial activity of the leek was the most effective when fresh leek extract was used, but it was stable after heat treatment at 68$^{\circ}C$ for 30 min or 98$^{\circ}C$ for 20 min. It was also relatively stable after incubated at pH 2.0 for 3 hrs. The antimicrobial activity in leek was not detected after dialysis with molecular weight cutoff of 12,000. Therefore it seems to be small molecule with molecular weight lower than 12,000.

• Journal of Microbiology and Biotechnology
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• v.29 no.10
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• pp.1636-1643
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• 2019

Two hydroxybenzoyl amines, 4-hydroxybenzoyl tyramine (4-HBT) and N-2-hydroxybenzoyl tryptamine (2-HBT), were synthesized using Escherichia coli. While 4-HBT was reported to demonstrate anti-atherosclerotic activity, 2-HBT showed anticonvulsant and antinociceptive activities. We introduced genes chorismate pyruvate-lyase (ubiC), tyrosine decarboxylase (TyDC), isochorismate synthase (entC), isochorismate pyruvate lyase (pchB), and tryptophan decarboxylase (TDC) for each substrate, 4-hydroxybenzoic acid (4-HBA), tyramine, 2-hydroxybenzoic acid (2-HBA), and tryptamine, respectively, in E. coli. Genes for CoA ligase (hbad) and amide formation (CaSHT and OsHCT) were also introduced to form hydroxybenzoic acid and amine conjugates. In addition, we engineered E. coli to provide increased substrates. These approaches led to the yield of 259.3 mg/l 4-HBT and 227.2 mg/l 2-HBT and could be applied to synthesize diverse bioactive hydroxybenzoyl amine conjugates.

• Journal of Microbiology and Biotechnology
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• v.32 no.8
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• pp.1047-1053
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• 2022

When ptsG, a glucose-specific phosphotransferase system (PTS) component, is deleted in Escherichia coli, growth can be severely poor because of the lack of efficient glucose transport. We discovered a new PTS transport system that could transport glucose through the growth-coupled experimental evolution of ptsG-deficient E. coli C strain under anaerobic conditions. Genome sequencing revealed mutations in agaR, which encodes a repressor of N-acetylgalactosamine (Aga) PTS expression in evolved progeny strains. RT-qPCR analysis showed that the expression of Aga PTS gene increased because of the loss-of-function of agaR. We confirmed the efficient Aga PTS-mediated glucose uptake by genetic complementation and anaerobic fermentation. We discussed the discovery of new glucose transporter in terms of different genetic backgrounds of E. coli strains, and the relationship between the pattern of mixed-acids fermentation and glucose transport rate.

• Food Science and Preservation
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• v.10 no.3
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• pp.421-426
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• 2003

Effects of acid, salt, heat treatment and natural antimicrobials on survival of E. coli O157:H7 CDF1, A. sobria CDF3 and S. aureus CDF2 isolated from surface of carcass in minced meat was investigated. The growth of E. coli O157:H7 CDF1 and A. sobria CDF3 inhibited in minced meat containing above 4％ NaCl but not in 1％ lactic acid. The growth of S. aureus CDF2 was not inhibited significantly by addition of 4％ NaCl but inhibited completely in minced meat containing 1％ lactic acid. Survival of A. sorbia CDF3 did not show any differences during storage at 4 and 10$^{\circ}C$. E. coli O157:H7 CDF10 and A. sobria CDF3 did not detect after heat treatment at 60$^{\circ}C$ for 10 min but S. aureus CDF2 decreased only 1 log after the same treatment. Viable cell of E. coli O157:H7 CDF1 decreased 2 log in TSB containing 0.5％ Oolong tea extract after incubation for 12 hr compared with control but A. sobria CDF3 and S. aureus CDF2 did not detect at the same condition. The growth of E. coli O157:H7 CDF1, A. sobria CDF3 and S. aureus CDF2 was not inhibited by addition of 0.3％ Oolong tea extract but inhibited by addition of 0.5％ Oolong tea extract in minced meat at 20$^{\circ}C$ for 24hr.