论文部分内容阅读
以一株蜡样芽孢杆菌为研究对象,其产毒基因以及产毒类型通过ELISA以及PCR鉴定,而后将其接种到米饭中并混合均匀,置于不同的温度条件下培养,温度分别设置为(10.0±0.2),(15.0±0.2),(20.0±0.2),(25.0±0.2),(30.0±0.2),(35.0±0.2)℃,研究其在米饭中生长以及产毒情况。采用修正的Gompertz模型构建初级生长模型,并在此基础进行产毒预测。结果表明,该株蜡样芽胞杆菌具有致泻型肠毒素基因,在15~35℃范围内该株菌在米饭中可产生肠毒素,随着培养温度的下降,开始产生毒素的时间也随之推迟;通过间隔取样检测到最初产毒素时的菌落总数范围为6.5~7.0 lg(CFU/g),采用插值计算校正后得到的实际开始产毒素时菌落总数范围为5.5~6.0 lg(CFU/g)。由于试验结果显示在15~35℃温度范围内蜡样芽胞杆菌是否产毒与其达到的浓度(菌落总数)有直接的相关性,因此从生长预测模型预测到的菌落数可用于判断产生毒素的风险程度。
A strain of Bacillus cereus was used as the research object. The toxigenic genes and toxigenic genes were identified by ELISA and PCR, then inoculated into rice and mixed well and incubated at different temperatures. The temperature was set to ( 10.0 ± 0.2), (15.0 ± 0.2), (20.0 ± 0.2), (25.0 ± 0.2), (30.0 ± 0.2) and (35.0 ± 0.2) ℃, respectively. A modified Gompertz model was used to construct the primary growth model, and based on this, the toxin production was predicted. The results showed that the strain Bacillus cereus has diarrhea-type enterotoxin gene, the strain in the range of 15 ~ 35 ℃ can produce enterotoxin in rice, with the incubation temperature decreased, the time to start toxin production also Postponement; the total number of colonies detected by spacer sampling in the first generation of toxins ranged from 6.5 to 7.0 lg (CFU / g) and the total number of colonies actually produced after toxin production corrected by interpolation ranged from 5.5 to 6.0 lg (CFU / g ). The number of colonies predicted from the growth prediction model can be used to determine the risk of toxin production as the test results show a direct correlation between the lethality of Bacillus cereus and the concentration reached (total number of colonies) within the temperature range of 15-35 ° C degree.