Glycosidase activities of Bacillus anthracis

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Abstract
B. anthracis was distinguished from the taxonomically related species B. cereus, B. mycoides and B. thuringiensis by a comparison of glycosidase activities. All the bacilli tested possessed .alpha.-glucosidase activity, as evidenced by the hydrolysis of p-nitrophenyl-.alpha.-D-glucoside. In B. anthracis, the glucosidase activity was enhanced by the addition of agents which damage cellular surface structures. Treatment of B. anthracis strains with toluene, Triton X-100 or mutanolysin or cellular disruption by sonication resulted in higher rates of .alpha.-glucoside hydrolysis than were accomplished by cells suspended in buffer. Intact B. anthracis cells may have a limited permeability to the glucosidase substrate. Triton X-100 markedly diminished the enzymatic hydrolysis of p-nitrophenyl-.alpha.-D-glucoside by strains of B. cereus, B. mycoides and B. thuringiensis. Triton X-100 also enhanced the .alpha.-maltosidase activity of B. anthracis but not that of the other bacilli. B. mycoides possessed an apparently inducible N-acetylglucosaminidase, although the enzyme was absent in B. anthracis. The glucosaminidase was inducible in the presence of p-nitrophenyl-N-acetylglucosamine in the absence of conventional N sources. Chloramphenicol prevented the induction of the glucosaminidase in B. mycoides. In several B. cereus and all B. thuringiensis strains, the glucosaminidase was constitutive. The results suggest a means for the rapid laboratory differentiation of B. anthracis from the other closely related bacilli. Assays for .alpha.-glucosidase and .alpha.-maltosidase, in the presence and absence of Triton X-100, can be used to distinguish B. anthracis from B. cereus, B. mycoides and B. thuringiensis. The hydrolysis of p-nitrophenyl-.beta.-N-acetylglucosamine induced by B. mycoides but not by B. anthracis provides an additional means for differentiating these similar bacilli.