Anthrax is caused by
Bacillus anthracis
, an endospore-forming soil bacterium. The genetic diversity of
B. anthracis
is known to be low compared with that of
Bacillus
species. In this study, we performed whole-genome sequencing of Zambian isolates of
B. anthracis
to understand the genetic diversity between closely related strains. Comparison of genomic sequences revealed that closely related strains were separated into three groups based on single nucleotide polymorphisms distributed throughout the genome. A large genomic deletion was detected in the region containing a bacitracin resistance gene cluster flanked by rRNA operons, resulting in the loss of bacitracin resistance. The structure of the deleted region, which was also conserved among species of the
Bacillus cereus
group, has the potential for both deletion and amplification and thus might be enabling the species to flexibly control the level of bacitracin resistance for adaptive evolution.
