The autolysin activity of B. thuringiensis strain was evaluated by the method of Raddadi et al. (2004) with a few modifications. Briefly, the cells grown in LB broth were harvested atOD600 1.2. The cells were washed inMES (2-Nmorpholino-ethansulfonic acid 50 mM, pH 6), resuspended in the same buffer, in potassium phosphate buffer (50 mM, pH 6.5) or Tris–HCl (50 mM, pH 8.5) buffers and incubated at 30C without agitation. The autolytic rate was expressed as the percentage decrease of the OD600 after 72 h. To evaluate hydrolase action of autolysins, commercially available substrate p-nitrophenyl-N-acetyl-b-D-glucosaminide (Sigma) and respective enzyme standard (b-N-acetylglucosaminidase of Canavalia ensiformis; Sigma) was used