Fig. 3.

Extracellular enzyme production in the isogenic revR strains. Quantitative assays were carried out to determine the relative amount of enzyme activity in 4-h cultures grown in TPYG medium or Todd-Hewitt broth (for sialidase assays only). Enzyme activity was measured using cell lysates for hyaluronidase activity (A) and using culture supernatants for protease activity (B), sialidase activity (C), and collagenase activity (D). All results are the averages of three biological replicates ± SEM; a significant difference as determined by Student's t test (P ≤ 0.05) is indicated by an asterisk.