Genome Announcements The Complete Genome Sequence of Bacillus anthracis Ames “Ancestor”

The pathogenic bacterium Bacillus anthracis has become the subject of intense study as a result of its use in a bioterrorism attack in the United States in September and October 2001. Previous studies suggested that B. anthracis Ames Ancestor, the original Ames fully virulent plasmid-containing isolate, was the ideal reference. This study describes the complete genome sequence of that original isolate, derived from a sample kept in cold storage since 1981. We describe the first complete whole-genome sequence (chromosome and plasmids) of a fully virulent isolate of Bacillus anthracis, that of the strain known as Ames Ances-tor. The B. anthracis Ames Ancestor strain was isolated in 1981 from a dead 14-month-old female Beefmaster heifer in Sarita, TX. Tryptose slant cultures of the B. anthracis isolate were acquired in February 1981 by researchers at the Unite