Characterization of the pathogenicity of a Bacillus cereus isolate from the Mariana Trench

ABSTRACT

Bacillus cereus is an important opportunistic pathogen widely distributed in the environment. In this study, we reported the isolation and characterization of a B. cereus isolate, MB1, from the Challenger Deep of the Mariana Trench. MB1 is aerobic, motile, and able to form endospores. It possesses 5966 genes distributed on a circular chromosome and two plasmids. The MB1 genome contains 14 sets of 23S, 5S, and 16S ribosomal RNA operons, 106 tRNA genes, 4 sRNA genes, 12 genomic islands, 13 prophages, and 302 putative virulence genes, including enterotoxins and cytolysins. Infection studies showed that MB1 was able to cause acute and lethal infection in fish and mice, and was highly toxic to mammalian cells. MB1 induced, in a dose-dependent manner, pyroptotic cell death, characterized by activation of caspase-1, cleavage of gasdermin D, and release of IL-1β and IL-18. MB1 spores exhibited swimming and haemolytic capacity, but were severely attenuated in pathogenicity, which, however, was regained to the full extent when the spores germinated under suitable conditions. Taken together, these results provide new insights into the biological and pathogenic mechanism of deep sea B. cereus.

KEYWORDS:

• Bacillus cereus
• deep sea
• pathogenicity
• cytotoxicity
• spore

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets generated for this study can be found in the GenBank accession numbers CP091971, CP091972 and CP091973.

Ethics statement

The live animal study was approved by The Ethics Committee of Institute of Oceanology, Chinese Academy of Sciences.

Author contributions

L.S., Y.W., and Z.Y. designed the study. J.Z. obtained the deep sea sample and isolated the bacteria. Y.W. conducted the experiments, analysed the data, and wrote the first draft of the manuscript. Z.Y. carried out the comparative genetic analyses. L.S. and Z.Y. edited the manuscript.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/21505594.2022.2088641.

Additional information

Funding

This work was supported by the grants from the Strategic Priority Research Program of the Chinese Academy of Sciences [XDA22050402]; the Collaborative Research Grant [KLMVI-OP-202002] of CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, and the Taishan Scholar Program of Shandong Province.