LETHALITY FOR MICE OF VEGETATIVE AND SPORE FORMS OF BACILLUS CEREUS AND BACILLUS CEREUS-LIKE INSECT PATHOGENS INJECTED INTRAPERITONEALLY AND SUBCUTANEOUSLY.

Lamanna, Carl (Army Research Office, Washington, D.C.) and Linda Jones. Lethality for mice of vegetative and spore forms of Bacillus cereus and Bacillus cereus-like insect pathogens injected intraperitoneally and subcutaneously. J. Bacteriol. 85:532-535. 1963.-Lethality for mice of Bacillus thuringiensis var. thuringiensis (two strains), var. sotto (one strain), var. alesti (one strain), and B. entomocidus var. entomocidus (one strain) maintained on artificial laboratory media is dependent upon the route of injection, the number of the bacilli, and their biological state, i.e., vegetative or spore form. Deaths did not occur upon subcutaneous injection of tenfold greater numbers of organisms than the ld(50) dose for the intraperitoneal route. From 10 to 100 times the number of spores were required to kill than vegetative bacilli given intraperitoneally. These observations duplicated those made with strains of B. cereus. For both types of spore forms, from 5 x 10(5) to 5 x 10(7) vegetative organisms were required for one intraperitoneal ld(50). With two strains of highly virulent B. anthracis, ld(50) values were the same for the vegetative and spore states, and for subcutaneous and intraperitoneal injections. Thus, the insect pathogenic sporeforming bacteria tested are more like B. cereus than like B. anthracis in their capacity to infect mice. The similarity to B. cereus extends to the rapidity of death after fatal injection of the insect pathogenic strains. The medical and taxonomic implications of the observations are discussed.