Arthrobacter (from the Greek, "jointed small stick”) is a genus of bacteria that's commonly found in soil. All species in this genus are Gram-positive obligate aerobes that are rods during exponential growth and cocci in their stationary phase. Colonies of Arthrobacter have a greenish metallic center on mineral salts pyridone broth incubated at 20°C. This genus is distinctive because of its unusual habit of "snapping division" in which the outer bacterial cell wall ruptures at a j… (More on Arthrobacter)