USEFUL CRITERIA FOR THE IDENTIFICATION OF BACILLUS ANTHRACIS AND RELATED SPECIES

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Abstract
The methods of Smith, et al for the identification of species of the genus Bacillus were applied to a collection of named cultures and to approximately 400 strains isolated from human and animal sources, dust and soil. In the course of this work certain additional and modified techniques were found to be helpful. The positive staining of the intracellular fat by Sudan-black B-safranin was a valuable first step in the identification of an unknown culture. Fermentation tests in tryptose agar butt-slants gave useful information, even though evidence of acid production is suppressed in particular instances by simultaneous alkali formation. Direct observations of the mode of spore germination confirmed the constancy of this process in each species, and emphasized the positive taxonomic value of the difference in the mode of germination in B. subtilis and B. licheniformis. Virulent strains of B. anthracis were readily recognized by a series of characteristics, without dependence upon motility or animal inoculation tests. In stock cultures, however, loss of virulence is accompanied by irregular appearance of properties similar to those of B. cereus. and positive identification of some of these avirulent strains of B. anthracis may remain uncertain unless their full history is known.