• Preventive Nutrition and Food Science
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• v.13 no.4
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• pp.370-374
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• 2008

The Gelidium corneum (GC)-whey protein isolate (WPI) blend film containing grapefruit seed extract (GSE) was prepared by incorporating different amounts (0, 0.02, 0.04, 0.08, 0.1%) of GSE into the film. The film's tensile strength (TS) and water vapor permeability (WVP) were improved by the addition of GSE. The film containing 0.1% GSE had a TS of 3.27 MPa, whereas the control had 2.64 MPa. WVP of the film was also significantly decreased by the addition of GSE. Addition of 0.1% GSE decreased the populations of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium by 1.0, 1.6, and 0.6 log CFU/g, respectively, compared to the control. Fish paste was packed with the GC-WPI blend film containing GSE, and microbial change in the fish paste inoculated with E. coli O157:H7, L. monocytogenes, and S. Typhimurium during storage was examined. Populations of E. coli O157:H7, L. monocytogenes, and S. Typhimurium were decreased by 0.60, 0.48, and 0.85 log CFU/g, after 7 day of storage, respectively. These results suggest packaging fish paste in the GC-WPI blend film containing GSE can extend the shelf life.

• Korean Journal of Pharmacognosy
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• v.36 no.2 s.141
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• pp.93-96
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• 2005

Mutagenicity of Gamgung-tang (GGT) was tested using in vitro S-9 mixture in vitro host-mediated assay with Salmonella typhimurium. In the previous reports, GGT was tested for the safety using Ames(-S-9), Bacillus subtilis Rec, and umu gene expression mutagenicity tests. Mutagenic activity in any assays we tested was not found. In this report, we further investigated safety of GGT after metabolic activation in vivo. Ames test with S-9 mixture and host-mediated assay with Salmonella typhimurium TA98 were used to identify metagenic property of GGT. GGT was administered 3 times with i.m. to Balb/c mice did not induced mutagenic effect in Salmonella typhimurium TA98 recovered from the liver after 3.5h with i.p. treatment. Over the entire dose range $(3{\sim}150mg/mouse)$ tested no toxicity was detected to the bacterial cells. These results suggest that there was no DNA damage and mutagenicity by GGT.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.842-845
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• 2008

This study was carried out to investigate the bactericidal efficacy of concentration (0.1, 0.2, and 0.4 ppm) and exposure time (10 and 30 min) of ozone on bacterial reduction rate of Salmonella typhimurium KCTC 2541 and Staphylococcus aureus ATCC 13515 in the distilled water (DW), and DW supplemented with 0.2% soluble starch (SS), and metal ion (MC) using argentums (Ag) and copper (Cu). The significant bactericidal differences of S. aureus were showed in the treatments of DW and SS, respectively, at the concentration of ozone above 0.1 ppm for 10 min, comparing the respective initial bacterial counts. The bacterial reduction of S. aureus was more sensitive than that of S. typhimurum at the same concentration of ozone. The bacterial reduction rate of SS treatment was slightly lower than that of DW treatment at the same concentration of ozone (p<0.05), however, the bacterial reduction rate of strains improved in the MC treatment compared to the DW treatment at the same concentration of ozone.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1464-1469
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• 1998

SOS Chromotest and Ames test were carried out to evaluate the mutagenicity of three chloropropanols. In the SOS Chromotest, 3-monochloro-l,2-propanediol (3-MCPD) and 2,3-dichloro-1-propanol (2,3-DCP) except for 1,3-dichloro-2-propanol (1,3-DCP) induced SOS response in Escherichia coli PQ37 with dose-response relationship and 2,3-DCP was far more genotoxic than 3-MCPD. The genotoxic activities of both compounds, however, were very lower in E. coli PQ35 (PQ37 $uvrA^+)$ as compared to them in E. coli PQ37, whereas much higher in E. coli PQ243 (PQ37 tagA alkA). These results indicate that there are at least two types of DNA lesions caused by these compounds; one is a excision-repairable and the other is 3-methyladenine or any similar lesion which is excision-unrepairable and can induce adaptive response. In Salmonella typhimurium TA100, all the compounds showed strong mutagenicities, establishing the following genotoxic order: 2,3-DCP>3-MCPD>1,3-DCP. But the mutagenic activities were very low in S. typhimurium TA98 and TA97a. These results suggest that the mutation by chloropropanols can be induced by the DNA lesions causing base-pair substitutions. From the result that the mutagenicities of 3-MCPD and 2,3-DCP in S. typhimurium TA1535 were very low as compared to those in S. typhimurium TA100, it was appeared that the mutations by both compounds necessitate error-prone SOS repair.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.564-570
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• 2003

The antibacterial mechanism of enterobacter Salmonella typhimurium was studied. The rfa (Waa) gene cluster of S. typhimurium encodes the core oligosaccharide biosynthesis of lipopolysaccharide (LPS). Among the rfa gene cluster, we recently cloned the rfaE gene, which is involved in ADP-L-glycero-D-manno-heptose biosynthesis. The rfaE mutant synthesizes heptose-deficient LPS, which consists of only lipid A and 3-deoxy-D-manno-octulosonic acid (KDO), thus making an incomplete LPS and a rough phenotype mutant. S. typhimurium deep-rough mutants with the heptose region of the inner core show a reduced growth rate, sensitivity to high temperature, and hypersensitivity to hydrophobic antibiotics such as baicalin isolated from the medicinal herb of Scutellaria baicalensis Georgi. Thus, in this study, the cloned rfaE gene was added to the S. typhimurium rfaE mutant strain SL1102 (rfaE543), which makes heptose-deficient LPS and has a deep-rough phenotype. The complementation created a smooth phenotype in the SL1102 strain. The sensitivity of SL1102 to bacteriophages was also recovered to that of wild-type strain, indicating that LPS is used as the receptor for bacteriophage infection. The permeability barrier of SL1102 to hydrophobic antibiotics such as novobiocin and baicalin was restored to that of the wild-type, suggesting that antibiotic resistance of the wild-type strain is highly correlated with their LPS. Through an agar diffusion assay, the growth-inhibition activity of baicalin was fully observed in the mutant SL1102 strain. However, only a half of the inhibitory activity was detected in the rfaE complemented SL1102 strain. Furthermore, the LPS produced by the rfaE-complemented SL1102 strain was indistinguishable from LPS biosynthesis of smooth strains.

• Journal of Food Hygiene and Safety
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• v.15 no.4
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• pp.297-303
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• 2000

Gamma irradiation at 20 kGy was applied to Kanjang (soy sauce), Doenjang (soybean paste), Kochujang (hot pepper pasts) and Chungkukjang for their possible genotoxicity. The genotoxicity of 20 kGy-irradiated samples was evaluated by Salmonella typhimurium reversion assay. The Salmonella tester strains included TA98, TA100, TA1535 and TA1537 in the absence and presence of an exogenous metabolizing system (59 mix). All samples were negative in the bacterial reversion assay with S. typhimurium TA98, TA100, TA1535 and TA1537. The results indicated that 20 kGy of gamma irradiation on water-soluble fraction of Kanjang, Doenjang, Kochujang and Chungkukjang were not shown mutagenicity.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.1
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• pp.96-99
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• 2003

The objective of this study was to evaluate the effects of various organic acids on microbial characteristics and Salmonella typhimurium in pork loins. Fresh pork loins were sprayed with various organic acids such as lactic acid, citric acid and acetic acid at various concentrations (0.5, 1, 1.5 and 2%). After spraying, the samples were packaged by HDPE film under air and stored at $4^{\circ}C$ for 14 days, and analyzed. Microbial deterioration of pork loins during the aerobic cold storage was delayed by organic acid spray. The bactericidal effect of acids increased with the increasing concentration. However, the inhibitory activity of organic acids during the storage varied with the kinds and concentrations of the acids. As for total plate counts, acetic acid was found to have the highest bactericidal activity, whereas citric acid was found to be the most inhibitory for coliform and S. typhimurium.

• Journal of Microbiology
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• v.45 no.1
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• pp.29-33
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• 2007

Salmonella typhimurium, causing mouse typhoid, infects hosts such as macrophage cells, and proliferates in intracellular vacuoles causing infected cells to trigger numerous genes to respond against the infection. In this study, we tried to identify such genes in RAW264.7 cells by using the PCR screening method with degenerate primers. Fourteen genes were found to be differentially expressed after a 4 h infection in which the expression of 8 genes increased while expression of the others decreased. Most of the genes were involved in proinflammatory responses such as cytokines production and cell death. The mutation in msbB gene encoding the myristoyl transferase in lipid A of lipopolysaccharide (LPS) resulted in much lower toxicity to the inoculated animals. We compared the expression of the identified genes in wild-type and msbB-mutated S. typhimurium infections and found that Lyzs encoding lysozyme type M was differentially expressed. This gene is quite likely to be related to bacterial survival in the host cells.

• Korean Journal of Microbiology
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• v.30 no.5
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• pp.347-354
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• 1992

New regulatory, loci which participate in the regulation of anaerobic inducible gene expression in Salmonella typhimurium were identified. We observed the regulatory network of new regulator mutations to various anaerobic inducible gene (1). Some anaerobic inducible lac fusions were also induced at low pH condition which was severe environment to withstand for its virulence at the place like phagolysosome. Sic oxygen-regulated regulatory mutants (oxr) isolated by Tn10 mutagenesis were divided into two groups. Five of them were found to show negative effect on the regulation of anaerobic gene expression, while on e showed positive effect on the regulation. Genetic loci of four oxr were identified with 54 Mud-P22 lysogens covering the whole chromosome of S. typhimurium, in the nearby region of map unit 87 min (oxr101), 63 min (oxr104), 97 min (oxr 105), and 57 min (oxr 106), respectively. Two oxr mutants were subjected to two-dimensional polyacrylamide electrophoretic analysis of anaerobic inducible proteins for searching the control circuitry of our oxr mutants.

• 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.