Detection, cloning and bioinformatics analysis of vip1/vip2 genes from local strains of Bacillus thuringiensis

Abstract

Bio-insecticides based on the spore forming bacterium, Bacillus thuringiensis (Bt) have been used for  commercial scale for the past 40 years. Bt is a Gram-positive soil bacterium that forms insecticidal crystal  proteins (ICPs) during sporulation; it has been characterized as an insect pathogen. Vegetative insecticidal  protein (VIP) is a newly discovered family of toxin protein isolated from Bt. A hundred strains of local Bacillus  thuringiensis were isolated from soil and dead larvae, identified by 16S rRNA and screened for the presence of vip1 and vip2 genes by polymerase chain reaction (PCR) amplification, with only four strains producing the desired bands of Vip1 and Vip2. The amplified fragments were cloned in pGEM-vector, sequenced and analyzed. The nucleotide sequences of vip1 (2.3 kb) and vip2 (1.3 kb) were given Gene-bank accession numbers: JN008908 and JN035904, respectively. Vip1 and Vip2 showed 99% homology with the previously isolated genes.

Key words: Bacillus thuringiensis, vegetative insecticidal proteins (vip1 and vip2), 16S rRNA, cloning.