Background Biotechnological advances in plant transformation and the genetic engineering of microbial insect control agents offer the potential of plants with increased tolerance to insect attack, and a new generation of microbial insecticides. One of the major limitations to these approaches is the availability of genes encoding products with insecticidal activity.
Entomopathogenic microorganisms are an obvious and rich source of insecticidal proteins.
This is both labour and time-intense, and has provided few useful genes and gene products. An alternative approach is to screen directly for insecticidal proteins in a manner analogous to chemical insecticide screening. Bacterial cells isolated from soils were incubated, lysed, and the filtered extracts were tested for protein levels before being assayed against the test insects. Genomic DNA and RNA from appropriate bacteria was used to prepare genomic libraries, and transformed into standard E. coli strains. Various recombinant DNA techniques were utilised for testing the gene products isolated.