What test is the most appropriate for differentiating Bacillus anthracis from other Bacillus species?

The most appropriate test for differentiating Bacillus anthracis from other Bacillus species is the Lecithinase test. Bacillus anthracis is uniquely identified by its ability to produce lecithinase, an enzyme that breaks down lecithin present in egg yolk. When a culture of Bacillus anthracis is grown on egg yolk agar, it will produce a characteristic opalescent zone around the colonies due to lecithin breakdown. This differentiates it from other Bacillus species that do not exhibit this enzymatic activity.

Other tests like the Penicillin susceptibility test, although indicative of susceptibility patterns, do not specifically differentiate between Bacillus anthracis and other Bacillus species. The glucose test primarily assesses fermentation capabilities, which is not distinctive for Bacillus anthracis. The motility test can show differences in mobility among species but is not reliable for identifying Bacillus anthracis since it does not provide specific evidence distinguishing it from closely related species. Thus, the lecithinase test stands out as the definitive method for this differentiation.