• Journal of Microbiology and Biotechnology
• /
• v.29 no.6
• /
• pp.962-972
• /
• 2019

Non-typhoidal Salmonella (NTS) is one of the most frequent causes of bacterial foodborne illnesses. Considering that the main reservoir of NTS is the intestinal tract of livestock, foods of animal origin are regarded as the main vehicles of Salmonella infection. In particular, poultry colonized with Salmonella Typhimurium (S. Typhimurium), a dominant serotype responsible for human infections, do not exhibit overt signs and symptoms, thereby posing a potential health risk to humans. In this study, comparative genomics approaches were applied to two S. Typhimurium strains, ST1539 and ST1120, isolated from a duck slaughterhouse and a pig farm, respectively, to characterize their virulence and antimicrobial resistance-associated genomic determinants. ST1539 containing a chromosome (4,905,039 bp; 4,403 CDSs) and a plasmid (93,876 bp; 96 CDSs) was phylogenetically distinct from other S. Typhimurium strains such as ST1120 and LT2. Compared to the ST1120 genome (previously deposited in GenBank; CP021909.1 and CP021910.1), ST1539 possesses more virulence determinants, including ST64B prophage, plasmid spv operon encoding virulence factors, genes encoding SseJ effector, Rck invasin, and biofilm-forming factors (bcf operon and pefAB). In accordance with the in silico prediction, ST1539 exhibited higher cytotoxicity against epithelial cells, better survival inside macrophage cells, and faster mice-killing activity than ST1120. However, ST1539 showed less resistance against antibiotics than ST1120, which may be attributed to the multiple resistanceassociated genes in the ST1120 chromosome. The accumulation of comparative genomics data on S. Typhimurium isolates from livestock would enrich our understanding of strategies Salmonella employs to adapt to diverse host animals.

• Journal of Life Science
• /
• v.24 no.1
• /
• pp.39-45
• /
• 2014

Salmonella typhimurium MMP13 and S. typhimurium ${\chi}8554$ were derived from weak JOL401 and strong ${\chi}3339$ virulent strains. Heat-labile subunit B (LT-B) was used as an adjuvant to increase the effectiveness of the vaccine. Plasmid pMMP184 carrying a ghost cassette was transformed into MMP13 and ${\chi}8554$ to produce the ghost, and the prepared ghost cells were administered into the muscles of BALB/c mice. In the absence of the adjuvant, the total IgG content showed a tendency to increase contrary to the original virulent strength. In contrast, in the presence of the adjuvant, the strain that originated from the strong virulent showed a tendency to promote the immune more than that of weak virulent strain. However, the final concentration of total IgG was similar between the compared groups, indicating that the originated virulent strength does not affect a specific immune. Other elements of the immunoglobulins IgG1, IgG2a, and sIgAs did not show a specific trend. The results of Salmonella challenge showed a similar tendency to regardless of the originated virulence. Taken together, the results suggest that the Salmonella ghost cells promoted the immune system of BALB/c mice, irrespective of the virulence applied to create the ghost cells.

• Korean Journal of Microbiology
• /
• v.20 no.1
• /
• pp.11-20
• /
• 1982

A study was undertaken to examine the effect of curing agents on the stability, curing and segregation of R plasmid pSL100. And also the stability, transfer frequency, and recombination of its segregants obtained from curing agent treatment were studied. Ethidium bromide, acridine orange, and mitomycin-C were used as curing agent. The results obtained were as follows ; 1. The curing agent ethidium bromide, acridine orange, and mitomycin-C were not effective for curing the multiple antibiotic resistant determinant of pSL100 in Salmonella typhimurium and Escherichia coli. However, they induced plasmid segregation with high frequency in S.typhimuruim LT-2strains. TcApSmCm, TcSmCmKm, TcApCm, TcAp, TcKm, Tc segregants were obtained. 2. The resistant markers of the segregents were transferred to S.typhimurium LT-2 strains with high frequencies whereas they were transferred to E.coli K-12 only with low frequencies. 3. The transconjugants obtained from conjugation between two different S.typhimurium segregants were similar to the phenotype of the original R factor pSL100 and the resistant markers were transferred to the S.typhimurium LT-2 or E.coli strain with equal frequencies, indicating that they are recombinants. 4. The transconjugants obtained from conjugation between pSL100 segrgants and pKM101, or pBR322 possessed the resistant markers of the two parental plasmids and they were transferred to both S.typhimurium and E.coli K-12 strains with the same frequencies and maintained stably, suggesting that they are also recombinants. 5. The recombinant pSL100 could be also obtained in rec A-strains of E.coli, suggesting that the gene function of rec A is required for the recombination of pSL100 segregants in E.coli.

• Korean Journal of Veterinary Research
• /
• v.34 no.1
• /
• pp.115-125
• /
• 1994

In this study, we try to establish the rapid and specific detection system for Salmonella species. The PhoE gene of Salmonella species was amplified with two specific primers, ST5 and ST8c, using PCR. The probe prepared from the amplified PhoE gene was sequenced and applied for Southern blot analysis. After PCR with ST5 and ST8c primers for PhoE gene, DNA bands of expected size(365bp) from 7 different Salmonella species were detected, but not from 12 enterobacteriaceae and 3 gram positive bacteria. PCR was highly sensitive to detect up to 10fg of purified DNA template and to identify Salmonella species with only 320 heat-lysed bacterial cells. The inhibition of PCR amplification from stool specimen was occurred with 50-fold dilution but disappeared over 100 fold dilution of samples. It was confirmed that the PhoE genes were amplified and cloned with over 97% nacleotide sequence homology of PCR products compared with that of S. typhfmurium LT2. The DNA probe derived from S. typhimurium TA 3,000 showed highly specific and sensitive reaction with PCR products of all tested Salmonella species. These results indicate that PCR was rapid and sensitive detection method for Salmonella species and DNA probe prepared from S. typhimurium TA 3,000 was specific to identify PCR products of different Salmonella species.

• Microbiology and Biotechnology Letters
• /
• v.5 no.4
• /
• pp.159-165
• /
• 1977

20 pesticides induding 11 insecticides, 5 herbicides and 4 fungicides have been tested for mutagenic activity in the Salmonella microsome system. It was found that Captan showed strong mutagenic activity directly in TA 1535, TA 100 and TA 98 strains, indicating that it induces both base substitution and frame shift mutation. With microsomal activation system, mutagenicity of Captan was slightly decreased. Micut, Dimethoate and Triforine revealed slight mutagenicity in TA100 without microsmal enzyme activtion.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.6
• /
• pp.1026-1034
• /
• 2016

In the current study, a total of 135 enterococci strains from different sources were screened for the presence of the enterocin-encoding genes entA, entP, entB, entL50A, and entL50B. The enterocin genes were present at different frequencies, with entA occurring the most frequently, followed by entP and entB; entL50A and L50B were not detected. The occurrence of single enterocin genes was higher than the occurrence of multiple enterocin gene combinations. The 80 isolates that harbor at least one enterocin-encoding gene (denoted "Gene⁺ strains") were screened for antimicrobial activity. A total of 82.5% of the Gene⁺ strains inhibited at least one of the indicator strains, and the isolates harboring multiple enterocin-encoding genes inhibited a larger number of indicator strains than isolates harboring a single gene. The indicator strains that exhibited growth inhibition included Listeria innocua strain CLIP 12612 (ATCC BAA-680), Listeria monocytogenes strain CDC 4555, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S. aureus ATCC 29213, S. aureus ATCC 6538, Salmonella enteritidis ATCC 13076, Salmonella typhimurium strain UK-1 (ATCC 68169), and Escherichia coli BAC 49LT ETEC. Inhibition due to either bacteriophage lysis or cytolysin activity was excluded. The growth inhibition of antilisterial Gene⁺ strains was further tested under different culture conditions. Among the culture media formulations, the MRS agar medium supplemented with 2% (w/v) yeast extract was the best solidified medium for enterocin production. Our findings extend the current knowledge of enterocin-producing enterococci, which may have potential applications as biopreservatives in the food industry due to their capability of controlling food spoilage pathogens.