Study of bioinformatics and phylogenetic relationship of Iranian Bacillus thuringiensis strains by using 16S rDNA gene sequence

Gram-positive , Bacillus thuringiensis, produces crystals with insecticidal properties. rDNA sequence analysis is used to study the evolution and classification of organisms. The study was conducted on 16SrDNA sequence of five native isolates of Bacillus thuringiensis using the polymerase chain reaction.

Characteristics and phylogenetic relationships between five sequences of native isolates along with other isolates in the genebank and other species of the genus Bacillus were performed with Mesquite and leBIBIQBPP database.

The five native isolates were 92.06 to 99.93% similar to each other and 99.73% to 100% similar to other isolates of Bacillus thuringiensis. Phylogenetic trees showed Bt1019, Bt1020 and Bt1039 in the first group and Bt1001 and Bt1091 in the second group. Based on Bt1001 sequence analysis using leBIBIQBPP, the minimum distance with Bacillus frigoritolerans was obtained. The sequence of Bacillus anthracis was close to Bt 1019. The Bt 1020 sequence was closest to Bacillus cereus. In the case of Bt1039, in addition to Bacillus cereus, the lowest distance was observed with Bacillus marcorinectum. The Bt1091 sequence showed the most similarity with Bacillus frigoritolerans.

Protein crystals were observed in the native bacteria. Toxic crystals are produced only by Bacillus thuringiensis. BLAST program for 16SrDNA gene sequence in the native isolates also showed the most similarity to Bacillus thuringiensis isolates in the genebank. Moreover, the results predicted that the three native isolates including Bt1019, Bt1020 and Bt1039 could be toxic against lepidopteran and two isolates including Bt1001 and Bt1091 could be toxic against coleopteran.