Genomic characterization of the Bacillus cereus sensu lato species: Backdrop to the evolution of Bacillus anthracis

• Type of Material: Article
• Authors: Michael Zwick, Emory University; Sandeep J. Joseph, Emory University; Xavier Didelot, University of Oxford; Peter E. Chen, Naval Medical Research Center; Kimberly A. Bishop-Lilly, Naval Medical Research Center; Andrew C. Stewart, Naval Medical Research Center; Kristin Willner, Naval Medical Research Center; Nichole Nolan, Naval Medical Research Center; Shannon Lentz, Naval Medical Research Center; Maureen K. Thomason, Naval Medical Research Center; Shanmuga Sozhamannan, Naval Medical Research Center; Alfred J. Mateczun, Naval Medical Research Center; Lei Du, Life Sciences, Inc.; Timothy D Read, Emory University
• Language: English
• Date: 2012-08
• Publisher: Cold Spring Harbor Laboratory Press
• Publication Version: Final Published Version
• Copyright Statement: © 2012, Published by Cold Spring Harbor Laboratory Press
• License: Creative Commons Attribution-Noncommercial 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1101%2Fgr.134437.111
• Title of Journal or Parent Work: Genome Research
• Volume: 22
• Issue: 8
• Start Page: 1512
• End Page: 1524
• Grant/Funding Information: This work was supported by a contract to 454 Life Sciences, Inc., from the Defense Threat Reduction Agency, and by grant TMTI0068_07_NM_T from the Joint Science and Technology Office for Chemical and Biological Defense (JSTO-CBD), Defense Threat Reduction Agency Initiative, to T.D.R.
• Research Categories: Biology, Genetics; Statistics; Chemistry, Biochemistry

Abstract

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.