FIG 1.

Two glutamate racemases in B. anthracis. (A) Organization of glutamate racemase genes racE1 and racE2 on the chromosome of B. anthracis Sterne. Arrowheads denote bursa aurealis insertion sites. (B) Disruption of glutamate racemase genes by allelic replacement. (C) Confirmation of racE1 and racE2 gene disruption by PCR amplification of the deleted locus with flanking primers. (D) Efficiency of transduction of the racE2 allele into the B. anthracis ΔracE1 mutant strain carrying plasmid pRacE2 or the vector (cloning plasmid) control. Spectinomycin-resistant colonies were enumerated after incubation of plates at 30°C for 24 to 30 h. Insertion of the correct racE2::aad9 allele was verified by DNA sequencing. Phage lysate of bslA::aad9 was used as a control. Data from three independent experiments are averaged, and the standard error of the mean is presented.