Multilocus sequence typing scheme for bacteria of the Bacillus cereus group

Area of Science:

• Microbiology
• Genetics
• Bacterial Pathogenesis

Background:

• The Bacillus cereus group, encompassing species like B. cereus, B. thuringiensis, B. weihenstephanensis, and B. anthracis, exhibits significant genetic diversity.
• This group is medically and industrially important due to the presence of pathogenic strains and strains with industrial applications.

Purpose of the Study:

• To develop a high-resolution multilocus sequence typing (MLST) scheme for the Bacillus cereus group.
• To analyze the genetic diversity and population structure of this bacterial group.

Main Methods:

• Developed an MLST scheme using seven conserved housekeeping genes (adk, ccpA, ftsA, glpT, pyrE, recF, sucC).
• Sequenced internal fragments (330-504 bp) from 77 diverse Bacillus cereus group strains.
• Analyzed sequence data to identify allelic profiles and sequence types (STs).

Main Results:

• Identified 25 to 40 alleles per locus, distinguishing a total of 53 unique sequence types (STs).
• The population structure of the Bacillus cereus group was found to be weakly clonal.
• All five analyzed B. anthracis isolates shared the same ST, indicating low genetic diversity within this species.

Conclusions:

• The developed MLST scheme provides high resolution for differentiating strains within the Bacillus cereus group.
• This MLST system is a valuable tool for investigating the population genetics and epidemiology of B. cereus group bacteria.
• The findings highlight the utility of MLST for tracking bacterial diversity and relatedness.