Comparison of Bacillus thuringiensis with other bacillus species based on enzymoserological examinations of their proteolytic enzymes.

Investigated strains of Bacillus thuringiensis were all good producers of casein precipitating proteinases (CP-enzymes). CP-enzymes produced by five strains of B. thuringiensis were serologically compared with enzymes produced by strains of B. cereus, B. licheniformis and B. subtilis. The technique used is a special enzymoserological procedure by which the proteolytic activity is neutralized by specific antisera. A close enzymoserological relationship was demonstrated between B. thuringiensis and B. cereus, while no interspecies cross-reactions occurred between enzymes of these species, and those of B. licheniformis and B. subtilis. The possibility of undetected transference of B. thuringiensis from bacteriologically treated plant material to animals is discussed in relation to the high degree of similarity between B. cereus and B. thuringiensis.