著者

RITSUKO KUWANA RYUJI YAMAZAWA KIYOSHI ITO HIROMU TAKAMATSU

出版者

The Society for Antibacterial and Antifungal Agents, Japan

雑誌

Biocontrol Science (ISSN:13424815)

巻号頁・発行日

vol.27, no.3, pp.143-151, 2022 (Released:2022-10-08)

参考文献数

27

被引用文献数

1

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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 14579T, 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 14579T, which may be used as an index for evaluating the sporulation progress of B. cereus.

著者

KOICHI NAKANISHI AKINORI KOGURE KEIJI DEUCHI RITSUKO KUWANA HIROMU TAKAMATSU KIYOSHI ITO

出版者

日本防菌防黴学会

雑誌

Biocontrol Science (ISSN:13424815)

巻号頁・発行日

vol.20, no.4, pp.291-295, 2015 (Released:2015-12-22)

参考文献数

9

被引用文献数

1

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We previously developed a method for evaluating the heat resistance of microorganisms by measuring the transition temperature at which the coefficient of linear expansion of a cell changes. Here, we performed heat resistance measurements using a scanning probe microscope with a nano thermal analysis system. The microorganisms studied included six strains of the genus Bacillus or related genera, one strain each of the thermophilic obligate anaerobic bacterial genera Thermoanaerobacter and Moorella, two strains of heat-resistant mold, two strains of non-sporulating bacteria, and one strain of yeast. Both vegetative cells and spores were evaluated. The transition temperature at which the coefficient of linear expansion due to heating changed from a positive value to a negative value correlated strongly with the heat resistance of the microorganism as estimated from the D value. The microorganisms with greater heat resistance exhibited higher transition temperatures. There was also a strong negative correlation between the coefficient of linear expansion and heat resistance in bacteria and yeast, such that microorganisms with greater heat resistance showed lower coefficients of linear expansion. These findings suggest that our method could be useful for evaluating the heat resistance of microorganisms.

著者

RITSUKO KUWANA RYUJI YAMAZAWA RYOKO ASADA KIYOSHI ITO MASAKAZU FURUTA HIROMU TAKAMATSU

出版者

The Society for Antibacterial and Antifungal Agents, Japan

雑誌

Journal of Microorganism Control (ISSN:27586383)

巻号頁・発行日

vol.28, no.1, pp.15-25, 2023 (Released:2023-05-08)

参考文献数

45

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Abstract: Ultraviolet (UV) -C is widely used to kill bacteria as it damages chromosomal DNA. We analyzed the denaturation of the protein function of Bacillus subtilis spores after UV-C irradiation. Almost all of the B. subtilis spores germinated in Luria-Bertani (LB) liquid medium, but the colony-forming unit (CFU) of the spores on LB agar plates decreased to approximately 1/103 by 100 mJ/cm2 of UV-C irradiation. Some of the spores germinated in LB liquid medium under phase-contrast microscopy, but almost no colonies formed on the LB agar plates after 1 J/cm2 of UV-C irradiation. The fluorescence of the green fluorescent protein (GFP) -fused spore proteins, YeeK-GFP, YeeK is a coat protein, decreased following UV-C irradiation of over 1 J/cm2, while that of SspA-GFP, SspA is a core protein, decreased following UV-C irradiation of over 2 J/ cm2, respectively. These results revealed that UV-C affected on coat proteins more than core proteins. We conclude that 25 to 100 mJ/cm2 of UV-C irradiation can cause DNA damage, and more than 1 J/cm2 of UV-C irradiation can cause the denaturation of spore proteins involved in germination. Our study would contribute to improve the technology to detect the bacterial spores, especially after UV sterilization.