Abstract

Biological control may reduce nematode populations to acceptable levels using Bacillus thuringiensis. Thus, the search for new cry proteins that are active on this type of target is highly relevant. To identify novel cry genes, B. thuringiensis isolates were analysed using molecular biology. The isolates with DNA sequences resembling genes that are effective against nematodes were fully sequenced through primer walking. The characterised novel cry gene was cloned in an expression vector, and the target protein was expressed at in an appropriate E. coli strain. The highest levels of protein expression were expressed at 18°C. To discern the nematotoxicity of this protein, bioassays were conducted using free living nematodes as targets. The bioassays revealed that the assessed free living nematodes were susceptible to the analysed cry protein. These results indicate that nematodes can be targets of cry protein produced by isolates of this bacterium.

Key words: Biological control, primer walking, cry proteins, bioassays.

Abbreviation

EDTA, Ethylene diamine tetra-acetic acid; ORF, open reading frame; SDS-PAGE, sodium dodecyl sulphate polyacrylamide gel electrophoresis; IPTG, isopropyl β-D-1-thiogalactopyranoside.