Fig. 2. Intercellular activation of PlcR regulon expression in the B.thuringiensis 407 Cry^– A′Z ΔpapR mutant strain. (A) The cells were grown on LB plates containing X-gal for 24 h at 37°C. The name of the strain is indicated beside each streak. (B) β-galactosidase activity of the B.thuringiensis 407 Cry^– A′Z ΔpapR cells resuspended in filtered B.thuringiensis 407 Cry^– (wild type) culture supernatant (circles) or in their own filtered culture supernatant (diamonds). The cells were grown at 37°C in LB medium.