La Duc Myron T, Satomi Masataka, Agata Norio, Venkateswaran Kasthuri
Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
J Microbiol Methods. 2004 Mar;56(3):383-94. doi: 10.1016/j.mimet.2003.11.004.
Bacillus anthracis, the causative agent of the human disease anthrax, Bacillus cereus, a food-borne pathogen capable of causing human illness, and Bacillus thuringiensis, a well-characterized insecticidal toxin producer, all cluster together within a very tight clade (B. cereus group) phylogenetically and are indistinguishable from one another via 16S rDNA sequence analysis. As new pathogens are continually emerging, it is imperative to devise a system capable of rapidly and accurately differentiating closely related, yet phenotypically distinct species. Although the gyrB gene has proven useful in discriminating closely related species, its sequence analysis has not yet been validated by DNA:DNA hybridization, the taxonomically accepted "gold standard". We phylogenetically characterized the gyrB sequences of various species and serotypes encompassed in the "B. cereus group," including lab strains and environmental isolates. Results were compared to those obtained from analyses of phenotypic characteristics, 16S rDNA sequence, DNA:DNA hybridization, and virulence factors. The gyrB gene proved more highly differential than 16S, while, at the same time, as analytical as costly and laborious DNA:DNA hybridization techniques in differentiating species within the B. cereus group.
炭疽芽孢杆菌是人类炭疽病的病原体，蜡样芽孢杆菌是一种可导致人类疾病的食源性病原体，苏云金芽孢杆菌是一种特性明确的杀虫毒素产生菌，这三种细菌在系统发育上都紧密聚集在一个非常紧密的进化枝（蜡样芽孢杆菌群）中，通过16S rDNA序列分析彼此无法区分。随着新病原体不断出现，设计一种能够快速准确区分密切相关但表型不同的物种的系统势在必行。尽管gyrB基因已被证明在区分密切相关物种方面很有用，但其序列分析尚未通过DNA:DNA杂交（分类学上公认的“金标准”）进行验证。我们对“蜡样芽孢杆菌群”中包括实验室菌株和环境分离株在内的各种物种和血清型的gyrB序列进行了系统发育特征分析。将结果与通过表型特征、16S rDNA序列、DNA:DNA杂交和毒力因子分析获得的结果进行了比较。结果表明，gyrB基因比16S基因具有更高的鉴别力，同时在区分蜡样芽孢杆菌群内的物种方面与成本高且费力的DNA:DNA杂交技术一样具有分析能力。
