Which characteristic helps differentiate Bacillus anthracis from other Bacillus species?

Bacillus anthracis is uniquely characterized by its non-hemolytic ground glass appearance on media such as blood agar. This morphology, along with its colony characteristics, aids microbiologists in differentiating it from other Bacillus species, which may exhibit hemolytic activity or different colony morphologies.

The "ground glass" phenotype refers to the smooth, opaque, and slightly mucoid appearance of the colonies, making it distinct when observed in culture. This distinctive appearance is linked to the unique composition of the bacterial surface and its poly-D-glutamic acid capsule, which is a virulence factor of Bacillus anthracis.

While Bacillus anthracis does produce spores and is capable of aerobic growth, these characteristics are not exclusive to it and can be found in other Bacillus species as well. Additionally, resistance to all antibiotics is not characteristic of Bacillus anthracis; it is susceptible to a range of antibiotics, particularly when treated early. Thus, the non-hemolytic ground glass appearance serves as the key differentiator for identifying Bacillus anthracis in a laboratory setting.