MORPHOLOGY OF 6 BACTERIOPHAGES OF STREPTOCOCCUS-THERMOPHILUS

The morphology of six phages of Streptococcus thermophilus, isolated in France from Gruyère cheese whey or yoghurt, was studied. They belong to Bradley's Group B and appear very similar. They possess a regular six‐sided head (size, 49–53 nm), of which the three‐dimensional structure is probably octahedral. The fairly long, non‐contractile tails (length, 200–224 nm; width, 8–9 nm) are flexible and regularly striated. They appear to be the juxtaposition of 60–63 annuli packed one above the other and are assumed to contain 240–252 capsomeres. In one preparation rare short‐tailed particles (tail length 130 nm) were also found. The tails have a terminal structure appearing either as a small plate, sometimes with a brush‐like appearance, or a plate with short prongs provided, in five out of the six phages studied, with a more or less long central fibre. Copyright © 1979, Wiley Blackwell. All rights reserved