The residual occurrences of Bacillus thuringiensis biopesticides in food and beverages

In 2006, 54 pasteurized full fat milk samples, 40 ice-cream samples, and two green-tea beverage samples were analyzed and a total of 19 Bacillus thuringiensis-like strains were isolated, nine from seven pasteurized milks, one from an ice-cream with peach pulp and juice, and nine from two green-tea beverages. These strains were classified as B. thuringiensis, contained the cry1A gene and produced crystal inclusions during sporulation. All strains were characterized by a serotyping test, SDS-PAGE, random amplified polymorphic DNA, and enterotoxic gene PCR analysis. Most isolates produced bipyramidal crystals and belonged to serotypes H3a3b, H5a5b, or H7. Furthermore, two strains from pasteurized full fat milks and three strains from green-tea beverages were indistinguishable from the B. thuringiensis subsp. kurstaki strains isolated from commercial biopesticides (Kaiyan®, Qiangdi®, Lvpuan® and Sutai®), suggesting the residual occurrences of B. thuringiensis from biopesticides in food and beverages.