FIG 6.

Capsule production and growth phenotypes of B. anthracis Ames glutamate racemase mutants. (A) The racE1::aad9 and racE2::aad9 alleles were transduced into B. anthracis Ames, yielding the racE1^Ames and racE1^Ames mutant isolates, which were spread along with wild-type strain Ames on BHI agar (left) or NYB agar with horse serum and incubated at 37°C with 5% CO₂ (right, capsule-inducing condition). (B) PDGA capsule production of colony material was analyzed by India ink staining and phase-contrast microscopy. Scale bar, 10 μm. (C) Spores (5 × 10⁶/ml) of B. anthracis Ames and its racE1^Ames and racE2^Ames mutants were inoculated into BHI broth (with or without 5 mM d-glutamate), and vegetative growth was monitored as increased A₆₀₀. (D) Spores (5 × 10⁶/ml) of B. anthracis Ames and its racE1^Ames and racE2^Ames mutants were inoculated into NBY broth supplemented with 0.8% sodium bicarbonate and 10% heat-inactivated horse serum (with or without 5 mM d-glutamate), and vegetative growth was monitored as increased A₆₀₀.