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 noninsecticidal 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 b-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.

Abundance and diversity of Bacillus thuringiensis in Bangladesh and their cry genes profile

“…Bt isolates were therefore inoculated (as dots with needle) onto Blood agar medium (nutrient agar containing 5% (v/v) sheep erythrocytes) and incubated overnight at 27 • C. Isolates forming clear zone of hemolysis around their colonies were considered as hemolytic (Ichikawa et al, 2008).…”

Phenotypic characterization of an indigenous Bacillus thuringiensis strain (B.T. LDC 501) expressing cancer cell killing protein

“…These results illustrated that there is no major dissimilarity in the phenotypic characteristics of the non-insecticidal strains from that of insecticidal ones (Ichikawa et al, 2008). Thus, biochemical analysis must be accompanied with molecular characterization in order to classify the microorganism.…”

“…Further resistance to bacitracin exhibited by B.t. LDC 501 strain is in contradiction to the PS1, PS2, PS3 and PS4 producers (Ichikawa et al, 2007;Ichikawa et al, 2008).…”

“…Carbohydrate utilization and spore aspect ratio of PS2, PS3 and PS4 producers were similar to that of insecticidal B.t. strains (Ichikawa et al, 2008). It is imperative to note that the cytotoxic Canadian isolate (M15) was unable to ferment starch like B.cereus (Jung et al, 2007).…”

“…Major phenotypic characters of the eight PS1 producers, PS2, PS3 and PS4 were compared and found to be similar with the insecticidal B. thuringiensis (B.t.) strains (Ichikawa et al, 2007;Ichikawa et al, 2008). Due to the selective cytotoxic nature, this organism can be exploited as potential therapeutic agent against cancer.…”