[Relationship between exoprotease activity, spore and crystal formation and virulence of bacteria of the group Bacillus thuringiensis].

Experiments were carried out to investigate the activity, spore and crystal formation and virulence of Bacillus thuringiensis. Bacteria of this group showed different exoprotease activity. Strains of one serotype differed in the level and time of occurrence of peak enzyme activity. Exoprotease activity of the bacteria cannot be indicative of their toxicity because it did not correlate with their virulence. Exoprotease activity can be used to characterize bacteria during their classification and to determine finer differences between strains within one serotype.