SONIC DISRUPTION OF AZOTOBACTER VINELANDII

Abstract

During the sonic treatment of A. vinelandii both direct count and turbidity decrease exponentially; the rate of change of turbidity is only 40% of the rate of change of direct count. Viable count and direct count decrease at essentially the same rate, which indicates that the mechanism of killing is disruption of the cell. The turbidity in excess of that contributed by residual cells results from the scattering of light by large fragments which retain the shape of the cell but appear empty; these fragments are designated as hulls. A single hit in the sound field disintegrates 40% of the hull and liberates all of the cytoplasm. The origin of various components of the cell liberated by sound can be established from their rates of release. A constituent of the cytoplasm is released at the same rate as the decrease in direct count; a constituent of the hull is released more slowly, at the same rate as the decrease in turbidity. On this basis glucose-6-phosphate dehydrogenase and ribonucleic acid are judged to be present in the cytoplasm while hydrogenase, cytochrome, and phospholipid appear to be in the hull.