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Spores of Bacillus cereus pose a threat to food safety due to their high resistance to the heat or acid treatments commonly used to make food microbiologically safe. Researchers from 3 SILS groups joined forces to analyse the protein composition of the outer layers of the spore. The results obtained were published in the Journal of Proteome Research and provide a deeper insight into the layered spore structure such as which proteins are exposed on the outside of the spore.

Bacillus Cereus spore
Schematic representation of the layered spore structure.

Bacillus spores can survive food safety treatments and later resume growth on foodstuffs or are capable, after ingestion, of producing toxins that cause either vomiting or diarrhea. The outer layers of the spore, the spore coat and exosporium, consist primarily of proteins that may serve as potential biomarkers for detection. The major morphogenetic protein CotE is important for correct assembly and attachment of the outermost layer, the exosporium, and by extension of the retention of many proteins. However, characterisation of the proteins affected by deletion of CotE has been limited to electrophoretic patterns.

Protein stoichiometry

Researchers from the Molecular Biology and Microbial Food Safety, Biosystems Data Analysis and Mass Spectrometry of Biomacromolecules groups together report the effect of CotE deletion on the insoluble fraction of the spore proteome through liquid chromatography–Fourier transform tandem mass spectrometry (LC–FTMS/MS) analysis. The resulting information is important for developing detection methods for targeting spores in a food safety setting. Furthermore, protein stoichiometry and determination of the abundance of germination mediating enzymes provides useful information for germination and outgrowth model development.

Publication details

Sacha K. Stelder, Celia Benito de Moya, Huub C. J. Hoefsloot, Leo J. de Koning, Stanley Brul, and Chris G. de Koster (20 December 2017) Stoichiometry, Absolute Abundance, and Localization of Proteins in the Bacillus cereus Spore Coat Insoluble Fraction Determined Using a QconCAT Approach Journal of Proteome Research Article ASAP

DOI: 10.1021/acs.jproteome.7b00732