| Summary: | 碩士 === 靜宜大學 === 食品營養研究所 === 93 === Bacillus cereus is one of the important food pathogens which may cause food poisoning. The B. cereus group comprises B. cereus, B. anthracis, B. thuringiensis and B. mycoides. These species share many phenotypic properties and high levels of chromosomal sequence similarity. The elongation factor Tu, encoded by tuf genes, is a GTP binding protein that plays a central role in protein synthesis. The highly conserved function and ubiquitous distribution render the elongation factor a valuable phylogenetic marker in the prokaryotes. In this study, by comparison of the gene sequences of the tuf for B. cereus group and other bacterial strains, we designed primers BCtuf1 and BCtuf3 specific to all the B. cereus group strains. The PCR products generated from this PCR primer set are 501 bp for B. cereus group. Also, none of the bacterial strains other than B. cereus group cells would generate the false positive reaction. Thus, the specificities of these PCR primers were assured. Primers BCtuf1/BCtuf3 and Hm1/Hm2 could be combined into a multiplex PCR system for the simultaneous detection of B. cereus group cells and the possible presence of the HBL gene. Either single or multiplex PCR systems allowed the detection of N × 100 CFU B. cereus cells per g of food samples if a 4-14h enrichment step was performed prior to the PCR. The primer set BCtufF/BCtuf5 was designed for PCR sequencing of the tuf gene of 4 B. cereus group strains. Between B. cereus ATCC 10987 and 3 B. cereus group strains（B. cereus BCRC 10603, B. anthracis ATCC 8705, B. thuringiensis BCRC 14616）, nucleotide sequences similarity ranged from 99.2 ％ to 99.9 ％. The nucleotide sequence similarity between BMY1 and B. cereus ATCC 10987 was 96.6 ％. The tuf gene specific primer set BCtuf1/BCtuf3 could be used in single and multiplex PCR assays for rapid and highly specific detection of B. cereus group.
|
|---|
