On the formation of crystal proteins during sporulation in Bacillus thuringiensis var. thuringiensis.

The processes of sporulation and crystal formation in Bacillus thuringiensis could be desynchronized, using short term temperature shift-up conditions or addition of chloramphenicol at the beginning of sporulation. Isolation of a Sp-, Cr+ mutant, blocked at early stage of sporulation further confirmed that crystal formation can occur in the absence of sporulation. The presence of one of the two antigenic subunits of the crystal protein in chloramphenicol treated cultures and both of them in cultures shifted up to 37 degrees C was demonstrated. The insect toxicity was exhibited by both the extracts.