Genomic characterization of the Bacillus cereus sensu lato species: backdrop to the evolution of Bacillus anthracis.
The key genes required for Bacillus anthracis to cause anthrax have been acquired recently by horizontal gene transfer. To understand the genetic background for the evolution of B. anthracis virulence, we obtained high-redundancy genome sequences of 45 strains of the Bacillus cereus sensu lato (s.l.) species that were chosen for their genetic diversity within the species based on the existing multilocus sequence typing scheme. From the resulting data, we called more than 324,000 new genes representing more than 12,333 new gene families for this group. The core genome size for the B. cereus s.l. group was ∼1750 genes, with another 2150 genes found in almost every genome constituting the extended core. There was a paucity of genes specific and conserved in any clade. We found no evidence of recent large-scale gene loss in B. anthracis or for unusual accumulation of nonsynonymous DNA substitutions in the chromosome; however, several B. cereus genomes isolated from soil and not previously associated with human disease were degraded to various degrees. Although B. anthracis has undergone an ecological shift within the species, its chromosome does not appear to be exceptional on a macroscopic scale compared with close relatives.
Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Michael E
ME
Zwick
Sandeep J
SJ
Joseph
Xavier
X
Didelot
Peter E
PE
Chen
Kimberly A
KA
Bishop-Lilly
Andrew C
AC
Stewart
Kristin
K
Willner
Nichole
N
Nolan
Shannon
S
Lentz
Maureen K
MK
Thomason
Shanmuga
S
Sozhamannan
Alfred J
AJ
Mateczun
Lei
L
Du
Timothy D
TD
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D001408:Bacillus anthracis / Q000145:classification / Q000235:genetics*; D001409:Bacillus cereus / Q000145:classification / Q000235:genetics*; D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D019143:Evolution, Molecular; D014644:Genetic Variation; D059646:Genome Size; D016680:Genome, Bacterial; D059765:Homologous Recombination; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D012641:Selection, Genetic; D016415:Sequence Alignment; D012988:Soil Microbiology
D004269:DNA, Bacterial