Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Genome Res. 2012 Aug;22(8):1512-24. doi: 10.1101/gr.134437.111. Epub 2012 May 29.
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.
炭疽杆菌引起炭疽病所需的关键基因最近通过水平基因转移获得。为了了解炭疽杆菌毒力进化的遗传背景，我们根据现有的多位点序列分型方案，从 Bacillus cereus sensu lato (s.l.) 种的 45 个菌株中获得了高冗余基因组序列，这些菌株在种内具有遗传多样性。从所得数据中，我们为该组调用了超过 324,000 个新基因，代表了超过 12,333 个新基因家族。B. cereus s.l. 组的核心基因组大小约为 1750 个基因，另外 2150 个基因几乎存在于每个基因组中，构成了扩展核心。几乎没有任何谱系特有的和保守的基因。我们没有发现炭疽杆菌最近大规模基因丢失的证据，也没有发现染色体上非同义 DNA 取代的异常积累；然而，一些从土壤中分离出来的、以前与人类疾病无关的 B. cereus 基因组在不同程度上受到了破坏。尽管炭疽杆菌在种内发生了生态转变，但与近亲相比，其染色体在宏观尺度上似乎并没有异常。
