Obtención de aislados de Bacillus thuringiensis Berliner autóctonos de Cuba

the presence of native isolates of bacillus thuringiensis was determinedby the analysis of 87 samples collected from different regions of cuba. the pasteurization was utilized for the selection of sporulating colonies growed in nutrient medium. the colonies were selected because of their aspect and morphology by stereoscopic observation. it was observed the typical bacilar shape, position and morphology of the endospore by light microscopy, characteristics of cereus group, bacillus genus. the bacterium was recognized basically due to the presence of a paraesporal crystal. the b. thuringiensis index obtainedwas determined by the relation between the numbers of b. thuringiensis colonies found with respect to the total number of colonies examined in the sample. 1-1,5 cm diameter colonies, plane, opaque, white-gray, lightly scabby consistence, irregular border, vegetative cells the typical bacilar shape and elipsoidal terminal endospores inside the vegetative cell allowed the selection of 609 sporulating colonies. from these, 341 colonies were classified as b. thuringiensis based on the production of parasporal crystal. b. thuringiensis isolates showed three crystal morphologies: bipyramidal mainly, amorphous, two isolates produced small parasporal bodies which appeared as a ？cap？ on the spore. the b. thuringiensis index varied from 0.37 to 0.74 and the b. thuringiensis index total was 0.56