蜡状芽胞杆菌群菌株中部分病原相关因子的检测

Detection of some toxin genes related to pathogenicity in Bacillus cereus group strains

对26株蜡状芽胞杆菌群菌株进行了肠毒素基因及其它病原相关因子的检测。PCR结果表明,17株蜡状芽胞杆菌群菌株中含有病原调控因子plcR的同源序列。采用3组溶血肠毒素hbl基因和3组非溶血肠毒素nhe基因特异性引物,分别可从73%的菌株中至少扩增出一个与预期DNA片段大小一致的片段,其中,苏云金芽胞杆菌菌株中溶血素hbl基因和非溶血素nhe基因的阳性检出率为83%。蜡状芽胞杆菌DBt248完全没有溶血活性,而且在溶血素hbl和非溶血素nhe基因的3个亚基以及病原调控因子plcR的PCR检测中均为阴性,有望作为宿主菌用于苏云金芽胞杆菌晶体蛋白的表达和应用。

Bacillus thuringiensis is a member of the B. cereus group, which also contains B. cereus, B. mycoides, B. pseudomycoides , B . anthracis and B . weihenstephanensis . Among them, B . thuringiensis and B . cereus share a high level chromosomal similarity and are phenotypically similar except that B. thuringiensis has insecticidal plasmid encoding crystal proteins. Twenty-six B. cereus group strains were surveyed in this study for the presence of enterotoxin genes and other toxin genes related to pathogenicity. PCR results showed that the pleiotropic virulence regulator plcR was presented in 17 B. cereus group strains. About 73% of the B. cereus group strains and 83% of the B. thuringiensis strains contained at least one of the three hbl genes and one of the three nhe genes, indicating that B. thuringiensis, including strains used commercially, had enterotoxin encoding genes. Additionally, B. cereus DBt248 was proved to be devoid of all three hbl genes, three nhe genes or plcR. Thus this strain might be a potential candidate as a host strain for expressing B. thuringiensis crystal toxins to construct safety insecticidal engineering strains without enterotoxic activity.