Characterization of the culture conditions that may affect the expression of the type 1 fimbriae in Salmonella enterica serotype Choleraesuis

• Main Authors: Shang-Chin Men, 門上勤
• Other Authors: 葉光勝
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/24963742853586851565

碩士 === 臺北醫學大學 === 醫學研究所 === 95 === Adherence is a prerequisite step for most of the bacteria to establish infection both in human and animals. The adherent event is mediated by the surface appendages called fimbriae. Fimbriae are hair-like protein structures on the outer membrane of the cell. They are produced by many members of the family Enterobacteriaceae including Salmonella. Salmonella enterica serotype Choleraesuis is an invasive serotype and can infect both human and swine. There are 15 different fimbrial operons that have the potential to produce fimbriae in S. Choleraesuis. Previous observation indicated that the most commonly found fimbrial type in the Salmonella serotypes is the type 1 fimbriae. Nevertheless, the type 1 fimbriae of S. Choleraesuis had not been characterized well. The objective of the present study is to investigate the type 1 fimbriae of S. Choleraesuis in more detail. Our result indicated that almost 70 % (64/98) of the S. Choleraesuis isolated from swine and 6 isolates from human did not produce type 1 fimbriae in the static broth culture condition which usually favors the type 1 fimbriae to express in another serotype S. Typhimurium. In both acidic and alkaline conditions changes the expression of type 1 fimbriae. The production of type 1 fimbriae in S. Choleraesuis was only observed among certain osmolarity range ( 0.06 M to 0.8 M NaCl ). Room temperature and 42 ℃ inhibited the type 1 fimbrial expression. Decreasing the concentration of agar to 0.6 % still did not promote S. Choleraesuis to exhibit type 1 fimbriae. The mRNA of fimA was detected by reverse-transcriptase PCR in most of the strains that did not produce type 1 fimbriae. Western blot data was also detected FimA , the result indicated that maybe posttranslational modification of FimA may occur. The fim gene clusters containing the DNA fragments of the S. Choleraesuis isolate from swine (fimbriated) and human (non-fimbriated) were subjected to sequencing. Comparison of these two sequences is 99 % consistent. The absence of type 1 fimbriae may be beneficial for S. Choleraesuis to spread systemically and escape from the immune attack of the host.