Screening for novel cry genes by hybridization

Aims: To develop an efficient and sensitive method to facilitate the search for novel Cry toxins. Methods and Results: The method uses a cocktail of cry gene sequences as a hybridization probe to screen Bacillus thuringiensis (Bt) strains and gene libraries prepared from them. Under the hybridization and washing conditions used, cross‐hybridization between genes from different cry families was not observed. Probes containing either partial or complete cry gene sequences produced similar patterns when hybridized to genomic DNA of several Bt strains although the pattern produced by the probe composed of entire gene coding regions was somewhat more complex. Conclusions: As a tool for gene library screening, hybridization with a mixture of cry gene sequences is an efficient means of detecting clones containing a diverse range of cry genes in a single step. Significance and Impact of the Study: This technique greatly improves the ease and efficiency of novel toxin gene discovery compared to previous methods.