Abstract
The loss of the 47 megadalton (Mdal) plasmid of Yersinia pestis resulted in increased gentian violet uptake and increased sensitivity to novobiocin. The addition of calcium caused a decrease in gentian violet uptake and a decrease in novobiocin sensitivity independent of the plasmid. Differentiation of cells bearing and lacking the plasmid was accomplished using novobiocin in the presence of calcium at 26 degree C. The novobiocin resistance levels of cells lacking the 47 Mdal plasmid and cells with the plasmid, but with an insertion in or a deletion in, or encomposing, the calcium dependence region of this plasmid, indicated that the resistance to novobiocin was not associated with the calcium dependence region, but was associated with a separate 47 Mdal plasmid region.