A purple and red pigmented bacterium move and swarm through cotton fabric to colour it. The top half of the fabric is impregnated with the antibiotic Cloxacillin. Purple is resistant to Cloxacillin so moves into this section of the fabric without a problem. Red however, is sensitive to Cloxacillin and initially cannot move into the antibiotic zone. It is though beginning to evolve resistance to Cloxacillin…….