FORMATION OF SPONTANEOUS ASPOROGENIC VARIANTS OF BACILLUS-THURINGIENSIS SUBSP GALLERIAE IN CONTINUOUS CULTURES

Bacillus thuringiensis subsp. galleriae forms spontaneous asporogenic, crystalliferous variants (Spo(-)Cry(+)) especially under continuous c ulture conditions. These variants gradually replace the wild-type stra in (Spo(+)Cry(+)) entirely in the culture. Spo(-)Cry(+) variants form amorphous insecticidal crystalline inclusion bodies, that are difficul t to solubilize and less toxic to the caterpillars of Bombyx mori. How ever, the defective inclusion bodies and their trypsin-digested peptid es exhibited similar antigenic profiles to that of native crystals in Western blot analysis. Apparently a block in the formation of spores d oes not affect the synthesis of the constitutive peptides of the cryst als but may interfere with the proper assembly of the crystalline endo toxin.