FIG. 1.

Characteristics of the S. aureus aconitase mutant. (A) Southern blot confirmation of acnA disruption. Genomic DNA was isolated from strains SA564 and SA564-acnA::ermB, digested with EcoRI and EcoRV (the acnA-containing fragment is ∼3,400 bp), and analyzed by Southern blotting. The ermB cassette was 1,280 bp, resulting in the ∼4.6-kb band observed in the mutant strain. (B) Aconitase activities of strains SA564 and SA564-acnA::ermB after 6 h of growth. (C) The wild-type strain SA564 and the aconitase mutant strain SA564-acnA::ermB were grown in TSB. At the indicated times, an aliquot was removed, appropriate dilutions were made, and the absorbance at 600 nm was measured. (D) Glucose depletion and acetate accumulation and depletion in the culture supernatants of strain SA564 and strain SA564-acnA::ermB plotted as a function of growth. (E) Net ammonia accumulation in the culture supernatants of strains SA564 and SA564-acnA::ermB. (F) An example of postexponential free amino acid depletion from the culture medium. The results presented are representative of at least two independent experiments.