Failure to phenotypically discriminate between non-insecticidal Bacillus thuringiensis strains with anticancer parasporins (PS2, PS3, and PS4) and Bacillus thuringiensis strains that produce insecticidal Cry proteins

Abstract

This study examined the microbiological features of the three reference strains of Bacillus thuringiensis whose non-insecticidal parasporal inclusions contain anticancer parasporins (PS2, PS3, and PS4). Morphometric analysis showed that the sizes and aspect ratios of the spores of these strains were in the range of those reported for the Bacillus cereus/B. thuringiensis group. The API 50CH test revealed that the carbohydrate utilization profiles of these strains were typical of the B. cereus/B. thuringiensis group. These parasporin producers proved resistant to ampicillin, and induced β-hemolysis on sheep blood agar. Overall results show that there is no significant difference in several phenotypic key characters between B. thuringiensis strains with PS2, PS3, and PS4 and those with insecticidal crystal proteins.