FIG. 4.

Activity of secreted amylase from B. subtilis 168 wild-type (wt) and sporulation- and motility-deficient strains. Amylase activity was quantified in the culture medium of the wild-type strain, the spo0A mutant, and the sigD mutant. All strains were transformed with the pKTHM10 plasmid (AmyQ overproduction), and levels of activity of secreted AmyQ were determined at different time points of growth by using the EnzCheck Ultra amylase assay kit as described in Materials and Methods. T0 corresponds to the transition phase of growth. Error bars represent standard errors over three independent biological replicates.