Determination and Distribution of cry-Type Genes of Bacillus thuringiensis Isolates from Taiwan

Using PCR with a set of specific oligonucleotide primers to detect cryI -type genes, we were able to screen the cry -type genes of 225 Bacillus thuringiensis soil isolates from Taiwan without much cost in time or labor. Some combinations of cry genes (the cry -type profile) in a single isolate were unique. We identified five distinct profiles of crystal genes from the B. thuringiensis soil isolates from Taiwan. The cry genes included cryIA ( a ), cryIA ( b ), cryIA ( c ), cryIC, cryID , and cryIV . Interestingly, 501 B. thuringiensis isolates (93.5% of the total number that we identified) were isolated from areas at high altitudes. The profiles of cry -type genes were distinct in all isolation areas. The distribution of cry -type genes of our isolates therefore depended on geography. Using PCR footprinting to detect cryIC -type genes, we identified two distinct cryIC footprints from some of our isolates, indicating that these isolates may contain novel cryIC -type genes. B. thuringiensis isolates containing cryIA ( a )-, cryIA ( b )-, and cryIA ( c )-type genes exhibited much greater activity against Plutella xylostella than did other isolates, indicating that multiple cry -type genes may be used as markers for the prediction of insecticidal activities. Images