Wild-type and mutant L. pneumophila invasion of H. vermiformis after growth to post-exponential phase in BYEα-ACES or BYEα-MOPS broth. (A). Comparison of wild-type L. pneumophila invasion of H. vermiformis after growth in BYEα-ACES or BYEα-MOPS broth. (B) Wild-type (WT) and STM-2, -3, -5, and -6 invasion after growth in BYEα-ACES broth. (C) Wild-type (WT) and STM-2, -3, -5, and -6 invasion after growth in BYEα-MOPS broth. (D) Ratio of mutant to wild-type invasion frequencies in H. vermiformis, after growth in BYEα-ACES broth (circle) and in BYEα-MOPS broth (square). Error bars, standard deviations.