FIG. 1.

Zymogen profiles of a gel containing low-fat milk. Lanes 1 to 5 are supernatants from the Sterne strain grown in NSM at 37°C with samples removed at 60-min intervals, commencing at the end of growth. Phase-white endospores were present in >80% of the cells by sample 4. Lanes 6 to 8 are for the plasmid-free strain, St-13, sampled at the same time as lanes 2, 4, and 5. Bands labeled A to E are discussed in the text (Fig. 2). In all cases, 5 μl of the supernatants was loaded from cultures grown to a Klett value of 230 or the equivalent (see Materials and Methods).