Faculty of Pharmaceutical Sciences, Setsunan University.
Biocontrol Sci. 2022;27(3):143-151. doi: 10.4265/bio.27.143.
Bacillus cereus is an important foodborne pathogenic bacterium. Although several B. cereus strains have been isolated from the environment, the differences among these strains with respect to spore formation ability and cell morphology need clarification. In this study, a phylogenetic tree was constructed based on the 16S rRNA gene sequences of nine strains of B. cereus. Spore formation and morphology of these nine strains were compared using both phase-contrast and fluorescence microscopy to create an index of the designated sporulation stages. Additionally, to investigate the efficiency of heat-resistant spore formation. Phylogenetic analysis revealed that five strains (ATCC 14579, NBRC 3457, NBRC 3514, NBRC 3836, and NBRC 13597) clustered together and the remaining four (ATCC 10987, NBRC 3003, NBRC 13494, and NBRC 13690) were genetically distinct from each other. Phase-contrast microscopy revealed significant differences in the sporulation stages among the nine strains. Furthermore, the efficiency of heat-resistant spore formation also differed, even among genetically related strains. In conclusion, a variety of cell morphologies during sporulation were observed among the nine B. cereus strains. We propose a designation of sporulation stages in B. cereus ATCC 14579, which may be used as an index for evaluating the sporulation progress of B. cereus.
蜡样芽胞杆菌是一种重要的食源性致病菌。尽管已经从环境中分离出了几种蜡样芽胞杆菌菌株，但这些菌株在形成孢子的能力和细胞形态方面的差异仍需阐明。在本研究中，根据 9 株蜡样芽胞杆菌的 16S rRNA 基因序列构建了系统发育树。使用相差和荧光显微镜比较了这 9 株菌的孢子形成和形态，以创建指定的孢子形成阶段指数。此外，为了研究耐热孢子形成的效率。系统发育分析表明，5 株（ATCC 14579、NBRC 3457、NBRC 3514、NBRC 3836 和 NBRC 13597）聚为一簇，其余 4 株（ATCC 10987、NBRC 3003、NBRC 13494 和 NBRC 13690）彼此在遗传上存在差异。相差显微镜显示，这 9 株菌的孢子形成阶段存在显著差异。此外，耐热孢子形成的效率也不同，即使是在遗传上相关的菌株之间。总之，观察到这 9 株蜡样芽胞杆菌在孢子形成过程中存在多种细胞形态。我们提出了在蜡样芽胞杆菌 ATCC 14579 中指定孢子形成阶段的方案，该方案可用作评估蜡样芽胞杆菌孢子形成进展的指标。
