ADHESION AND CYTOTOXICITY OF BACILLUS-THURINGIENSIS TO CULTURED SPODOPTERA AND DROSOPHILA CELLS

Two Bacillus thuringiensis strains were tested for the ability to adhe re to cultured Spodoptera and Drosophila insect cells. The wild-type s train is virulent and motile and readily adheres to and kills both typ es of insect cells. The avirulent mutant strain, which lacks flagella and several other of the proposed virulence factors, does not adhere t o the insect cells and does not kill these cells efficiently. Purified flagella bind to insect cells; addition of anti-flagella serum abolis hes cell binding and reduces the killing efficiency. Both bacteria and culture supernatant from the wild-type strain, but not from the mutan t, are cytotoxic. Of the factors known to be reduced in the avirulent mutant, such as flagellin and phosphatidylcholine (PC) degrading or ph osphatidylinositol-specific phospholipase C (PLC), only PC-PLC is show n to be cytotoxic. (C) 1995 Academic Press, Inc.