The soil-dwelling bacterium Bacillus cereus is a close relative of the microbe responsible for anthrax, and can cause a similar illness if it is inhaled by people with damaged lungs.

Olaf Schneewind and his co-workers at the University of Chicago in Illinois find that a pathogenic strain of B. cereus harbours two sets of genes that encode protective sugar coats. These coats prevent the bacteria from being engulfed and destroyed by certain immune cells. One gene set produces a protective capsule made of the sugar hyaluronic acid, whereas the other capsule is made of an unidentified sugar.

Knocking out one set of the capsule-making genes reduced the microbe's virulence in mice; if both were knocked out, the bacteria no longer caused disease.

Mol. Microbiol. doi:10.1111/j.1365-2958.2011.07582.x (2011)