Bacteriophages of Clostridium saccharoperbutylacetonicum

Abstract

The fine structure of phage HM 2 (group I) active on Clostridium saccharoperbutylacetonicum was studied by an electron microscopy with a negative-staining technique, and compared with those of more conventional types, phages HM 3 (group II) and HM 7 (group III), whose tails were clearly observed by a shadow-casting technique. This study revealed that phage HM 2 had an intricate tail which was not observed by a shadow-casting technique. Phage HM 2 has an icosahedral head about 450Å in diameter and a non-contractile tail about 300Å long. The distal 130Å of the tail axis has a width of 80Å which is wider than the upper portion of the tail (50 to 60Å). The distal enlargement is not seen in the hollow tail. Twelve fibrous-shaped appendages are attached symmetrically at the upper portion of tail axis and extend toward the distal base of the tail. Their length is a little shorter than 300Å. They combine with divalent cations in the phage dilution medium, and also adsorb the host cell debris. Phage HM 3 has an icosahedral head about 770Å in diameter and a tail about 1000Å long and 150Å wide with contractile sheath. Phage HM 7 has an icosahedral head about 750Å in diameter and a long non-contractile tail about 2000Å long and about 120Å wide with forked tip. The structure of the tail of phage HM 2 is quite different from those of phages HM 3 and HM 7 hitherto described and those of the various phages of other bacteria.