Incomplete and Aberrant Particles of Actinophage MSP2 from Lysates of Streptomyces venezuelae

Abstract

Lysates of actinophage MSP2, propagated on Streptomyces venezuelae S13, contain at least 10 11 PFU/ml. During purification by centrifugation methods and by adsorption chromatography, a number of types of aberrant and incomplete phage particles were seen by electron microscopy. Infectious MSP2 had a buoyant density in CsCl of 1.52 g/cm 3 and an absorbance at 260 nm relative to that at 280 nm ( A 260 / A 280 ) of 1.53. Empty capsids banded at 1.276 g/cm 3 and partially filled capsids banded at 1.351 g/cm 3 , and A 260 / A 280 ratios were 0.77 and 1.24, respectively. Two kinds of light capsids found in CsCl fractions of 1.278 g/cm 3 probably include the 1.276 component. Some capsids were joined by tail-like structures. Ghosts and polyheads also were present. Aberrant particles observed by electron microscopy included two-tailed actinophage, phage with abnormal tail positions, and large-headed phage.