1982 Volume 28 Issue 1 Pages 1-6
The fine structure of PL-1 phage active against Lactobacillus casei ATCC 27092 was investigated by negative staining and the rotation technique. The phage had an isometric hexagonal head, about 60nm in diameter and a flexible and presumably non-contractile tail about 280nm long and 12nm wide. The tail had a terminal appendage appearing as a small plate with prongs to which was attached a short filament. Periodic cross-striations with about 60 turns were observed along the tail axis. Ultrasonic treatment of the phages produced a number of doughnut-shaped particles lying end-on in addition to the tail fragments disrupted to various degrees. Rotation prints of the doughnut-shaped particles showed that they were composed of six morphological subunits surrounding the central hole of about 5nm diameter. It appeared plausible that the tail tube consists of serially connected morphological subunits forming such doughnut-shaped particles.
