Role of superoxide in the germination of Bacillus anthracis endospores
2005
Baillie, L. | Hibbs, S. | Tsai, P. | Cao, G.L. | Rosen, G.M.
The spore forming Gram-positive bacterium Bacillus anthracis, the causative agent of anthrax, has achieved notoriety due to its use as a bioterror agent. In the environment, B. anthracis exists as a dormant endospore. Germination of endospores during their internalization within the myeloid phagocyte, and the ability of those endospores to survive exposure to antibacterial killing mechanisms such as superoxide (oxygen free radical), is a key initial event in the infective process. We report herein that endospores exposed to fluxes of oxygen free radical typically found in stimulated phagocytes had no effect on viability. Further endospores of the Sterne strain of B. anthracis were found to scavenge oxygen free radical, which may enhance the ability of the bacterium to survive within the hostile environment of the phagolysosome. Most intriguing was the observation that endospore germination was stimulated by a flux of oxygen free radical as low as 1 micromolar/min. Data presented herein suggest that B. anthracis may co-opt oxygen free radical which is produced by stimulated myeloid phagocytes and is an essential element of host immunity, as a necessary step in productive infection of the host.
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