Arthrobacter sp. - Gram-positive to Gram-variable, coryneform, pleomorphic, soil bacterium. This genus is unique because of its unusual habit of "snapping division" in which the outer cell wall ruptures at a joint. This type of cell division in which rods break into cocci is referred to as reversion. Arthrobacter spp. have been found to perform important biodegradable functions in soil and sediment.