How to to identify Bacillus cereus group with MALDI TOF MS

What is Bacillus cereus group?

The Bacillus cereus group, also known as B. cereus sensu lato, is a subdivision of the Bacillus genus that comprises several closely related species of Gram-positive, rod-shaped, spore-forming bacteria. The group includes eight formally recognized species: B. cereus sensu stricto, B. anthracis, B. thuringiensis, B. weihenstephanensis/B. mycoides, B. pseudomycoides, B. cytotoxicus, and B. toyonensis.

These bacteria are widespread in nature and are commonly associated with food poisoning, intestinal infections, and other pathogenic potential. The B. cereus group has been the subject of extensive research, and its taxonomy and species status have been determined based on phenotypic characteristics and genotypic methods, including Whole Genome Sequencing. The bacteria within this group have a wide range of virulence factors and can cause foodborne illness, localized wound and eye infections, as well as systemic disease.

Additionally, certain strains of B. thuringiensis are entomopathogens and have been commercialized for use as biopesticides, while some strains have been reported to cause infection in immunocompromised individuals.

The phylogeny of the B. cereus group is based on chromosomal genes, and the assignment of a specific isolate to a single species or phylogenetic group can be complicated due to the presence of important virulence and phenotypic traits that are plasmid-borne and can be lost or horizontally transferred.

In summary, the Bacillus cereus group encompasses a diverse set of bacteria with pathogenic potential and has implications for food safety, public health, and microbiology research.

Commercial MALDI-TOF MS systems can only differentiate species of the Bacillus cereus group with difficulty, often only at the group level.
However, the adapted work-up protocols and the Mabriteccentral.com algorithm enable a clear differentiation of all B. cereus group species using MALDI-TOF MS.

How we identify Bacillus cereus group with MALDI TOF MS

Fresh sample

Short incubation time (3-5 hours) to minimise the formation of spores

Sample preparation

Washing of sample and physical distruption with glass beads

Spectra acquisition

Sinapic acid as matrix in a massrange from 4-30kDa

Mabriteccentral.com

Identification and interpretation by mabriteccentral and it’s algorithm.