Isolation Bacillus genus and biochemical Identification of B. thuringiensis and it`s ecological distribution from some Iranian soils and also introducing soil as a strength source of this bacterium. Using a standard isolation method with specific

Bacillus thuringiensis is a spore-forming bacterium showing the unusual ability to produce endogenous crystals during sporulation that are toxic for some pest insects. This work was performed to study the Isolation Bacillus genus and biochemical Identification of B. thuringiensis and it`s ecological distribution from some Iranian soils and also introducing soil as a strength source of this bacterium. Using a standard isolation method with specific medium, B. thuringiensis was isolated from 23 out of 30 soil samples collected in the Soil and Water Research Institute (SWRI) of Iran. The bacillus population percentage mean of samples` total bacteria population was (44.44%) and B.thuringiensis population percentage mean of total bacteria population was 3.45%. Maximum and minimum B.T. population logarithms were 4.78 and 0 for sample number 2759 and 7 samples had no B.T. population, respectively. Using Muller Hilton agar for total bacteria population and Hicrome Bacillus Agar for bacillus genus population and then biochemical Identification of bacillus isolates showed a great biodiversity among soil samples, which were distributed among different species, including megaterium, polymixa and cereus etc. We found variable percentages of B.thuringiensis isolates among soil samples and knew about soil as a valuable source of this bacterium to use in biological pesticides and insecticides because of their high ability against pests and insects. Keywords— Bacillus thuringiensis, Insecticides, Geographical diversity.