CYTOTOXIC ACTIVITY IN CULTURE FILTRATES FROM THE ENTOMOPATHOGENIC FUNGUS BEAUVERIA-SULFURESCENS

The hyphomycete fungus Beauveria sulfurescens secretes into the cultur e medium several components toxic for Galleria mellonella larvae. Conc entrated and dialyzed (cutoff 12,000) B. sulfurescens culture filtrate also contains a high-molecular-weight compound cytotoxic for the Mame stra brassicae cell line. A fractionation in two chromatographic steps separated a cytotoxic fraction (IC50 = 1.15 +/- 0.05 mu g/ml), which was poorly toxic to larvae (LC(50) = 150 +/- 10 mu g/ml) and an insect icidal fraction (LC(50) = 2.1 +/- 0.1 mu g/ml) devoid of detectable cy totoxicity. The two kinds of activity, i.e., cytotoxicity in vitro and toxicity in vivo are thus independent. The cytotoxic activity, initia lly detected on a M. brassicae cell line, also affected two other inse ct cell lines (G. mellonella and Spodoptera frugiperda). The cytotoxic fraction provoked not only the inhibition of cell proliferation, but also cell death. Adhesive mammalian cell lines were not sensitive. Non adhesive mammalian cell lines of murine myeloma and hybridomas were po orly sensitive. (C) 1994 Academic Press, Inc.