Description:
B. thuringiensis has been studied worldwide over the past decades, mainly because this gram-positive
bacterium produces significant amounts of crystal protein toxic activity against economically important insect
larvae. Most strains of B. thuringiensis produce delta-endotoxin crystals toxic to lepidopteran insects such
moth. But some strains of B. thuringiensis produce delta-endotoxin crystals toxic to dipteran insects such as
mosquitoes and blackflies. Numerous chemical insecticides have been used to control some insects. While
chemical insecticides have knock down effect, they are too expensive in the developing countries and harmful
to both humans and the environment. In addition, target insect pests develop biological resistance rapidly
especially at higher rates of application. Thus, the increase in pesticidal application to control this pest has
urged to researcher to search for biological control alternatives that would be a good component of Integrated
Pest Management. To clone and analyze B. thuringiensis gene fragments isolated by restriction digest PCR.
Specific primers were designated to amplify the genes of B. thuringiensis serovar entomocidus INA 288, and
the PCR products were classified and re-amplyfied by PCR to obtained the fragments for subsequent
purification and cloning into the pGEM-T vectors, followed by rapid identification. The recombinant plasmid
were extracted from positive clones and the target gene fragments were sequenced. The sequence analysis
showed that cry4Aa had similarity with cryINA 288. It seems a novel mosquitocidal cry gene. It may be
concluded that dipteracidal polypeptide of entomocidus INA 288 (cryINA 288) consisted of 703 amino acids
with conserved blocks and amino acid sequence was aligned to that of cry4Aa. Furthemore, an aligment of the
conserved block sequences among the cry INA 288 and other mosquitocidal proteins was performed.
Key words: Bacillus thuringiensis, Clone and sequence, Entomocidus INA 288