FIG 1.

Growth and viability of B. anthracis variants expressing single lcp genes. (A) The ΔlcpB1B3B4C quadruple mutant, which still carries the lcpB2 and lcpD genes, was transformed with a plasmid containing lcpB2 (plcpB2) or the cloning vector, and these strains were used as recipient strains for transduction of the lcpD::aad9 allele using bacteriophage CP51. The plcpB2-bearing strain is merodiploid for lcpB2. Following transduction, bacteria were plated on spectinomycin-containing medium and incubated at 30°C for 30 h. Recombination of the lcpD::aad9 allele was verified by DNA sequencing and occurred only in the merodiploid strain. (B) Overnight cultures of wild-type (WT) B. anthracis Sterne and isogenic variants expressing a single lcp gene were normalized to A₆₀₀ of 5, diluted 1:100 into fresh medium, and grown at 37°C. Growth was monitored by recording the change in cell density (absorbance) at 600 nm every 30 min over 12 h. (C) After 6 h following dilution in fresh medium (as described for panel B), cultures were serially diluted, and 5-μl aliquots of each serial 10-fold dilution (0 through −7) were plated on agar medium. An image of the plate after overnight incubation at 30°C is shown.