[Protein composition of crystals (delta-endotoxin) of different serotypes of Bac. thuringiensis].

The crystals of entomopathogenic protein from Bac. thuringiensis contain admixtures of proteinases adhering to their surfaces. A newly developed technique of protease inactivation allowed to estimate the true protein composition of the crystals of various strains of Bac. thuringiensis. It was shown that the crystals of all strains (with the exception of V and VIII) are composed of only one protein with molecular weights of 145,000, 135,000 and 130,000, depending on the strain. The crystals of serotype VIII and the majority of the V serotype strains have two proteins with molecular weights of 135,000 and 130,000. A method for estimation of the protein composition of crystal without their preliminary isolation from a crystal--spore mixture is proposed.