• Korean Journal of Veterinary Research
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• v.38 no.3
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• pp.606-613
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• 1998

Cadmium is one of the well-known environmental toxicants and induces cancer in rodents and human, but its carcinogenic mechanism has not been well demonstrated until now. Genotoxic effects of cadmium in Salmonella typhimurium TA98, TA100 and TA1535/pSK1002 or in WB-F344 rat liver epithelial cells were investigated to elucidate the tumor initiating effects of cadmium. TA98, TA100 and TA1535/pSK1002 tester strains were used to detect frameshift mutation, base-pair mutation and SOS repair response, respectively, in Salmonella mutation test. Reverse mutations from histidine to $histidin^+$ of Salmonella typhimurium TA98 and TA100 by $CdCl_2$ were not significantly different from control up to the maximum doses ($100{\mu}M$ and $200{\mu}M$ in TA98 and TA100, respectively) at which non-cytotoxicity was observed. DNA SOS repair responses(${\beta}$-galactosidase activity) generally did not show significant increases compared to control in both of the conditions with or without metabolic activation in Salmonella typhimurium TA1535/pSK1002 by $CdCl_2$. But the activities of ${\beta}$-galactosidase by $400{\mu}M$ of $CdCl_2$ in metabolic activation condition and by 130 and $400{\mu}M$ of $CdCl_2$ in non-metabolic activation condition were more decreased than those of control. DNA single strand breaks for 4hrs were observed only in WB-F344 rat liver epithelial cells treated with $200{\mu}M$ of $CdCl_2$. As a conclusion, $CdCl_2$ did not induce gene mutation in microbials but induce DNA single strand breaks in rat liver epithelial cells.

• Molecules and Cells
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• v.28 no.4
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• pp.389-395
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• 2009

We previously observed that the transcription of some flagellar genes decreased in Salmonella Typhimurium tdcA mutant, which is a gene encoding the transcriptional activator of the tdc operon. Since flagella-mediated bacterial motility accelerates the invasion of Salmonella, we have examined the effect of tdcA mutation on the invasive ability as well as the flagellar biosynthesis in S. Typhimurium. A tdcA mutation caused defects in motility and formation of flagellin protein, FliC in S. Typhimurium. Invasion assays in the presence of a centrifugal force confirmed that the defect of flagellum synthesis decreases the ability of Salmonella to invade into cultured epithelial cells. In addition, we also found that the expression of Salmonella pathogenicity island 1 (SPI1) genes required for Salmonella invasion was down-regulated in the tdcA mutant because of the decreased expression of fliZ, a positive regulator of SPI1 transcriptional activator, hilA. Finally, the virulence of a S. Typhimurium tdcA mutant was attenuated compared to a wild type when administered orally. This study implies the role of tdcA in the invasion process of S. Typhimurium.

• Journal of Microbiology and Biotechnology
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• v.18 no.4
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• pp.742-745
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• 2008

Inactivation of Escherichia coli O157:H7 and Salmonella typhimurium was evaluated on inoculated chicken by aqueous chlorine dioxide ($CIO_2$) treatment. Chicken samples were inoculated with 6-7 log CFU/g of Escherichia coli O157:H7 and Salmonella typhimurium, respectively. The chicken samples were then treated with 0, 50, and 100 ppm of $CIO_2$ solution and stored at $4{\pm}1^{\circ}C$. Aqueous $CIO_2$ treatment decreased the populations of the pathogenic bacteria on the chicken breast and drumstick. In particular, 100 ppm $CIO_2$ treatment on the chicken breast and drumstick reduced Escherichia coli O157:H7 and Salmonella typhimurium by 1.00-1.27 and 1.37-1.44 log CFU/g, respectively. Aqueous $CIO_2$ treatment on the growth of the bacteria was continuously in effect during storage, resulting in the decrease of the populations of Escherichia coli O157:H7 and Salmonella typhimurium. These results suggest that aqueous $CIO_2$ treatment should be useful in improving the microbial safety of chicken during storage.

• Journal of Microbiology
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• v.42 no.1
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• pp.14-19
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• 2004

Salmonella enterica serovar Typhimurium DT104 (Salmonella Typhimurium DT104 or DT104) has been emerging as a common pathogen for human in Korea since 1997. In order to compare the genomic relationship and to search for the dominant strains in Korea, we conducted pulsed-field gel electrophoresis (PFGE) and IS200 fingerprinting of 25 epidemiological unrelated isolates from human and animals from Korea and cattle from America. Two Salmonella Typhimurium DT104 isolates from human in Korea and all 8 isolates from American cattle had indistinguishable patterns from the PFGE and IS200 fingerprinting but multidrug-resistant Salmonella Typhimurium isolates, including DT104, from Korean animals had diverse genetic patterns. The data suggest that a dominant DT104 strain might have circulated between Korean and American cattle and that it had a high level of clonality.

• Korean journal of food and cookery science
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• v.14 no.5
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• pp.468-474
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• 1998

This study was performed to determine the effects of antimutagenicity from Barley (Hordeum vulgare). In Salmonella typhimurium reversion assay (In vitro test), the extract of Barley (Hordeum vulgare) inhibited mutagenic activity of 4-NQO and Trp-p-1 with 59 mix. in Salmonella typhimurium TA98 and TA100. In Micronucleus test (In vivo test), the methanol extract of Barley (Hordeum vulgare) inhibited micronucleus formation in bone marrow by cyclophosphamide. The $\beta$-glucan of Barley (Hordeum vulgare) showed inhibitory effects of 59-77% in mutagenic activity of 4-NQO by Salmonella typhimurium TA100. The mutagenicity of Trp-p-1 with S9 mix. by Salmonella typhimurium TA98 showed inhibitory effects of 24-56%. The methanl extract (M) was fractionated with ether (MI), ethylacetate (M2), buthanol (M3) and water (M4). The Antimutagenicity of Trp-p-1 with 59 mix. by Salmonella typhimurium TA98 in Barley fraction showed the following: methanol extract (99.58%)>ether fraction (98.05%)>buthanol fraction (56.90%)>water fraction (56.72%)>ethyl acetate fraction (28.72%). Among them, ether fraction in TA 98 showed strong antimutagenicity effects (85.56%, 98.05%) against mutation induced by 4-NQO and Trp-p-1. As concentration of the methanol extract increased (1.25~5 g/kg/10 cc), micronucleus formation in bone marrow by chemical mutagen (CP) showed inhibitory effects of 50% (p< 0.05).

• Korean Journal of Veterinary Research
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• v.30 no.2
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• pp.193-201
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• 1990

An attempt was made to isolate Salmonella(S) organisms from a total of 4,587 fecal samples of birds during the period from May 1987 to March 1988, and serotype and biotypes of the isolates were also investigated. One hundred and sixty-six Salmonella strains were isolated from 151(3.3%) of 4,587 fecal samples of birds, and their serotype was all identified as S typhimurium var copenhagen. The positive samples of S typhimurium var copenhagen were 149 samples(5.1%) in pigeons and 2 samples (0.8%) in aquatic birds. No Salmonella was obtained from ducks, pheasant, and other birds. The isolation frequencies of S typhimurium var copenhagen from pigeons varied from 1.1 to 12.8% at 5 parks, it was higher in September and November. Biotypes of 166 S typhimurium var copenhagen strains isolated from pigeons and aquatic birds were all biotype 10 according to Brandis' method, and were biotype 25hi (78.3%), 27 hi (14.5%), 25 fhi (3.6%), 25 bhi (1.8%), 27 bhi (0.6%), 27 hiz (0.6%), and 9 hi (0.6%) according to Duguid's scheme. Appearance of different biotypes indicated the occurrence of exotic infection sources on the parks.

• Journal of Radiation Industry
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• v.7 no.2_3
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• pp.109-113
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• 2013

In a previous study, a relatively high dose of gamma radiation (1 kGy) did not fully induce typical SOS genes such as sulA, recA, recN, and din in Salmonella Typhimurium (S. Typhimurium) (Lim et al. 2008, Gene expression profiles following high-dose exposure to gamma radiation in Salmonella enterica serovar Typhimuium. J. Radiat. Ind. 3:111-119). In this study, we examined changes in the transcriptional repertoire of S. Typhimurium after a dose of 10 Gy using DNA microarrays. It was found that more than half (~65%) of the 26 up-regulated genes belong to the SOS regulon: ten genes are typical SOS genes, and seven genes are Salmonella prophage genes, which are known to be activated by LexA cleavage. Among 29 down-regulated genes, the function of five genes with the most decreased expression is associated with carbohydrate transport and energy production. This suggests that upon exposure to gamma radiation cells may cease growing by reducing the metabolic activity, and repair DNA damage using a DNA repair system such as the SOS response system. The difference in expression of the SOS genes between a high (1 kGy) and low (10 Gy) dose of radiation shows the possibility that cells may opt for one of multiple regulatory circuits in response to the specific gamma radiation dose.

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.172-172
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• 2005

• Korean Journal of Food Science and Technology
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• v.40 no.3
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• pp.349-353
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• 2008

This study was performed to determine the adherence rates of standard type Salmonella Typhimurium (ST) and wild type Salmonella spp.(WT) in pork after the following contact types and times at $10^{\circ}C$: pork meat (2, 6, 24 hr), conveyer belt (2, 6 hr), stainless steel (2, 6 hr), and cutting board (2, 6 hr). After 6 hr of pork meat to meat fat contact, the adherence rates for ST and WT were approximately 4.21 and 26.87%, respectively, and after 6 hrs of pork meat to red meat contact they were 16.40 and 27.48%, respectively. However, after 24 hr of both types of contact, ST and WT showed 100% adherence rates. The adherence rates for ST after 2 hr and 6 hr of pork meat to conveyer belt contact were 1.34 and 0.60%, respectively, while the adherence rate for WT was 5.14% after 6 hr of contact. After pork meat to stainless steel contact, ST showed adherence rates of zero and 1.59% after 6 and 24 hr of contact, respectively, while the adherence rates for WT ranged from 0.17% after 2 hr to 5.01% after 6 hr. On the other hand, neither ST nor WT offered adherence data following pork meat to cutting board contact. These results suggest that the adherence rates of ST and WT after pork meat to pork meat contact or pork meat to processing surface contact were significantly affected by the contact time and WT presented much higher adherence rates for both types of transmission than ST.

• Natural Product Sciences
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• v.11 no.3
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• pp.160-164
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• 2005

The effects of Cymbopogon citratus essential oil (Lemongrass oil) and its main component, citral (84.30%), on antibiotic-susceptible and -resistant strains of Salmonella enteritidis and S. typhimurium were assessed. C. citratus oil and citral significantly inhibited all strains of the two Salmonella species examined, with minimum inhibiting concentrations (MICs) ranging from 0.5 mg/ml to 8.0 mg/ml. The combined effects of C. citratus oil and citral (84.30%) were evaluated using a checkerboard microtiter assay. Essential oil fractions of C. citratus and citral exhibited strong synergistic or additive effects with streptomycin or kanamycin against S. typhimurium strains with fractional inhibitory concentration (FIC) indices in the range of 0.28 to 1.00. In conclusion, a combination of streptomycin and lemongrass oil or its main component, citral, may be useful for reducing the minimum effective dose of antibiotic required for the treatment of resistant S. typhimurium infections.