Bacillus sphaericus Spore Germination and Recycling in Mosquito Larval Cadavers

Naturally occurring mosquito pathogenic strains of Bacillus sphaericus are able to recycle in mosquito larval cadavers. The efficiency of spore germination and recycling in cadavers varied among strains. Strains producing the sporeassociated binary toxin had spores that germinated in high percentage. The spores of a strain producing the vegetative, cell-associated 100-kDa toxin germinated less well. Nontoxic strains supplied with either the binary toxin or the 100-kDa toxin displayed poor spore germination and recycling ability. The results indicate that the toxins do not function directly as spore germinants. Efficient spore germination and recycling may have evolved in bacteria producing the sporeassociated binary toxin to take advantage of the nutrientrich larval cadaver.