Abstract
Morphological properties of the P- and Ap-series phages described in previous papers were examined by means of electron microscopy, analytical centrifugation, CsCl densitygradient centrifugation and ultrafiltration.
In view of the buoyant density of phage particles, fourteen Brevibacterium phages were classified into four groups, i.e., the phages under group I had buoyant density of 1.511 to 1.514g em-3, and those under groups II, III and IV, densities of 1.482, 1.492 and 1.508g cm-3, respectively; and above grouping corresponded to that by the serological chracteristics of the phages.
Electron microscopic observation by means of shadow-casting or negative staining recognized all the phages as tadpole-shaped; their particles having polyhedral head (40-70mμ in diameter) and long tail (80_??_275mμ in length).
In relation to particle sizes of the phages as estimated by all of above-mentioned methods, no significant differences were observed between the sizes calculated from ultrafiltration and those obtained directly from electron micrographs by negative staining.
