[Detection of enterotoxin genes in Bacillus thuringiensis by PCR]

The presence of hemolysin HblA (hblA), enterotoxin BceT (bceT) and enterotoxin S (entS) genes from 45 strains of B. thuringiensis, 4 strains of B. cereus and B. sphaericus have been detected respectively by multiple PCR. The results showed that 95.6% B. thuringiensis strains contain the B component of hblA gene, 91.1% and 93.3% of them contain bceT and entS genes sequences respectively. The enterotoxin productions in all strains have also been analysis using two commercial immunoassay kits(TECRA and RPLA) and it has proved that most of B. thuringiensis stains and the positive B. cereus strain can produce entero toxins during their growth. However, the two hblA sequence positive stains, DBT007 was negative when tested both by RPLA and Tecra, T24 001 was negative when assayed by Tecra and positive by RPLA. One hblA sequence negative strain Dmu39 was negative when tested by RPLA but positive by Tecra. No enterotoxin and enterotoxin gene could be detected in B. thuringiensis DBT248 and the B. sphaericus strains. The results suggest that the potential risk of using B. thuringiensis, as biopesticide needs to be further evaluated.