Protein expression patterns in Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium) strains with diverse phenotypes, such as phage type, antibiotic resistance pattern and plasmid profiles were examined. For detailed analysis of proteins expressed by different S. Typhimurium strains, protein fractions were divided into detergent-rich phase (DP) and aqueous phase (AP) using triton X-114 detergent. The two phases were subjected to two-dimensional gel electrophoresis (2-DE), followed by protein identification using peptide mass fingerprinting (PMF). In the results, PMF showed that DP fractions consisted mainly of outer membrane proteins, whereas the AP fractions included cytosolic proteins. Comparison of 2-DE profiles of DP did not show any distinct protein spots which could be correlated with phage type, antibiotic resistance pattern or plasmid profile. However, comparisons of 2-DE profiles of the AP revealed differences in the protein spots, which could be correlated with the plasmid profile and phage types. Among these protein spots, flagellin was specific for strains containing a 90 kb plasmid. Compared to DT193 phage type, three protein spots in the range of pI 5.0-5.5 and MW 8-15 kDa of AP 2-DE profiles were absent in the DT104 phage types. Additionally, a protein spot with PI in the range of 4.5-5.0 and molecular weight (MW) between 51-69 kDa was specific for phage type DT104, while a protein spot with pI in the range of 4.0-4.8 and MW between 18-20 kDa was specific for DT193 phage type. These protein spots may be useful for discriminating phage types of S. Typhimurium.

This study was carried out to investigate the serotype, and antimicrobial susceptibility and analyze the plasmid profile for the 145 isolates of L. monocytogenes isolated from livestock products and these product processing plants in Gyeongnam, Korea. All of L. monocytogenes strains belonged to serotype 1/2b (57.9%), 1/2a (20.0%), 4b (11.4%), 1/2c, 3b, 4c (each 2.9%) and 4d (0.7%). Serotype 1/2b, 1/2a, 4b from each source were found predominantly. Serotype 1/2b was predominantly higher than other serotype, and there was no significant difference between serotypes isolated from livestock products and product processing plants.

Nine strains of Yersinia species isolated from pigs and dogs in Korea, comprising 5 strains of Yersinia enterocolitica, 2 strains of Y. kristensenii and each strain of Y. pseudo-tuberculosis and Y. intermedia, were examined for the presence of virulence-associated plasmids, calcium dependency and provocation of guinea pig conjunctivitis (Sereny test). Three strains of Y. enterocolitica isolated from pigs were positive in calcium dependency and harbored one plasmid of about 45 megadalton, but negative in Sereny test

To investigate the epidemiological trait of intestinal diseases of animals caused by thermophilic Campylobacter spp., isolation of etiological agent was carried out and the profiles of plasmids and the transfer of resistance plasmid in the isolated Camplyobacter spp. were examined. A total of 110 isolates of C jejuni and C coli were subjected to the test for the presence of plasmid DNA. Of the isolates examined, 60 % of the isolates were noted to harbor plasmid DNA. Plasmid occurrence rate from pigs, chickens and cattle were 76.2 %, 61.7 % and 37.7 %, respectively. The plasmids of a large molecular weight, ranging from 36 Md to 86Md, were identified with the strains of tetracycline resistant. Transfer frequency of tetracycline resistant plasmids was higher in the case of the filter mating method than in the broth mating method by the factor of 10-1,000. Tetracycline resistant plasmids of C jejuni were transferarble to C jejuni and C coli by conjugation. In a low frequency, the transfer of tetracycline plasmid was also possible to Vibrio parahemolyticus. However, it was impossible to transfer to Streptococcus fecalis, E. coli and Vibrio cholerae. Tetracycline resistant plasmids of C jejuni were impossible to transfer to Campylobacter spp. and related bacteria by transformation