Study of iron-uptake mechanism and cloning of iron-regulated genes in Salmonella choleraesuis

• Main Authors: I-Hsien Wu, 吳怡先
• Other Authors: Chao-Fu Chang
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/11532764245727878619

碩士 === 國立臺灣大學 === 獸醫學研究所 === 88 === The iron-acquisition ability of bacteria is associated with its pathogenesity and virulence. The investigations of Salmonella iron-uptake mechanism are mostly done on Salmonella typhimurium. Although Salmonella choleraesuis, the agent of swine salmonellosis, also an important zoonosis pathogen, causes great economic lost, the mechanisms of iron utilization of S. choleraesuis are still not clear. To understand the effect of iron to the growth of S. choleraesuis, we proceeded with the growth curve analysis under iron-restricted and normal condition. The result showed that S. choleraesuis in iron-restricted medium could not grow as well as it dose in the normal medium in 16 hours. Ten strains of S. choleraesuis isolated from clinically affected swine farms in Taiwan were processed by chrome azurol S (CAS) assay. The result indicated that all these strains were able to produce siderophores on condition that iron was restricted. We found that S. choleraesuis could produce catechol but not hydroxamate siderophores by the general bioassay. The result of the iron-acquisition assay indicated that S. choleraesuis could use FeCl3, FeSO4, pig hemoglobin, bovine hemoglobin, bovine holo-transferrin, human holo-transferrin, human lactoferrin (iron saturated form) but not hemin as its iron sources. We have utilized the fur titration assay (FURTA) to screen the genomic library of S. choleraesuis and got eleven clones that had fur-box homologous region. Six of the eleven clones had iron-uptake genes or iron regulated genes, fes, iroB, cir, fepB, fepCGD and fepA. We will try to sequence the entire genes, which have fur boxes. To understand the gene expression and the functions of its products, we will isolate the gene products and test their cytotoxicities and antigenicities. On the basis of those researches, we expect to develop attenuated vaccine to help porcine industry in preventing and controlling salmonellosis.