GERMINATION OF BACILLUS-THURINGIENSIS SPORES IN BACTERIOPHAGOUS NEMATODES (NEMATODA, RHABDITIDA)

During screening of Bacillus thuringiensis isolates for nematicidal ac tivity it was observed that spores of B. thuringiensis germinated in t he intestine of bacteriophagous nematodes in the presence of antibioti cs. This phenomenon was studied more closely by scanning electron micr oscopy. The nematodes were fed with bacterial spore-crystal mixtures i n axenic culture medium supplemented with tetracyclin and chlorampheni col. Germination of spores was rare but was more frequently observed i n Panagrellus redivivus than in other nematode species investigated. G ermination of spores in the nematode intestine resulted in the coloniz ation of the entire nematode within 24 hr. Crude nematode tissue prepa rations supported germination and subsequent growth of B. thuringiensi s spores and vegetative cells. The mechanism for the loss of antibioti c activity in the nematode intestine is unknown. Since B. thuringiensi s requires a nutrient-rich environment for reproduction, e.g., a cadav er, bacteriophagous nematodes may serve as suitable hosts for B. thuri ngiensis. (C) 1995 Academic Press, Inc.