Microbiology

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Science  21 Nov 2003:
Vol. 302, Issue 5649, pp. 1295
DOI: 10.1126/science.302.5649.1295b

When environmental conditions take a turn for the worse, Bacillus species seek shelter by changing into extraordinarily resistant spores, which can then germinate after conditions improve. Using atomic force microscopy, Chada et al. investigated the topography of the spore surface. The spore is a multilayered protective shell consisting of up to 60 different proteins encoded by the cot gene family. Of the three species studied, Bacillus cereus and B. anthracis sport an outermost glycoprotein layer called the exosporium, whereas the B. subtilis spore coat is naked. The spore coats could be differentiated by their distinctive patterns of major ridges and thousands of circular bumps. The ridges may be folds resulting from dehydration of the spore core, and the bumps may encircle minute pores that allow influx of the signals that trigger germination but exclude larger, potentially toxic molecules. Both features were obscured by the exosporium, but this structure was not always present in the B. cereus and B. anthracis samples. Spores of cot mutants exhibited varied surface patterns, indicative of specific roles for these genes in coat assembly and structure. — CA

J. Bacteriol. 185, 6255 (2003).

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