Discrimination between B. cereus and B. thurengenesis using 16S rDNA sequencing.

This paper mainly emphasizes on the methods for the identification and discrimination of closely related species. Two isolates resembling Bacillus thuringenesis were isolated from soil and dead insects and analyzed by traditional biochemical methods. Biochemical results for this isolate were similar to that of Bacillus thuringenesis. For further confirmation a set of synthetic oligonucleotide homologous to broadly conserved sequence was used for in-vitro amplification via polymerase chain reaction followed by direct sequencing. The 16S rDNA sequencing after Blast analysis confirmed the bacterial isolate as Bacillus cereus, which causes food born disease syndrome associated with enterotoxin, whereas Bacillus thuringenesis is an insect pathogen. The 16S and 23S rRNA currently considered as the most useful molecules for the determination of prokaryotic phylogeny. Analysis of these rRNA sequences has resulted in tremendous expansion of our knowledge of prokaryotic diversity and has demonstrated the limitations of the existing prokaryotic taxonomy which is based primarily on the analysis of phenotypic traits. Discrimination between B. cereus and Bacillus thuringenesis is a challenging debate to which this paper makes contribution. Thus it is difficult task to discriminate between closely related species like Bacillus thuringenesis from Bacillus cereus by any traditional methods and the fact that they have grouped together in our analysis and other recent studies is not surprising.