And so they can see how bacteria have evolved from harmless strains into really nasty ones again and again and again. (scientificamerican.com)
«FIP develops when a usually harmless strain of FCoV mutates in the cat in a way that gives the virus the ability to replicate itself in some of the cat's white cells. (www2.vet.cornell.edu)
But in the region controlling the production of sugars found in the bacterium's cell walls, they found a stretch of DNA from a normally harmless strain (EMBO Journal, vol 14, p 209). (newscientist.com)