Separation of three biologically distinct activities from the parasporal crystal ofBacillus thuringiensis var.israelensis

Abstract

Three fractions showing biologically distinct activities were isolated from theBacillus thruingiensis var.israelensis crystal δ-endotoxin. Using a shallow sodium chloride gradient on a DEAE anion-exchange column, three pooled fractions were obtained consisting of the 25Kd peptide; 25,26Kd peptides; and 31,34,35Kd peptides, respectively. The 25Kd peptide was hemolytic against human erythrocytes but not mosquitocidal. The 25,26Kd peptide mixture was hemolytic, not mosquitocidal, but toxic to larvae ofTrichoplusia ni when injected into the hemocoel of these animals. The 31,34,35Kd peptide mixture was toxic to mosquito larvae, but neither hemolytic nor toxic to larvae ofT. ni upon injection. In addition, teratogenic effects were observed when wandering larvae ofT. ni were injected with each of these three fractions. All of the biological activities described were destroyed when peptides were treated for 15 s at 95°C or greater. The hemolytic activity was elevated by heating the peptide(s) at 70°C for 15 s. On the other hand, this elevation was not observed with the two insecticidal activities.