Physical properties and the fine structure of proteocines.

Proteocines derived from twelve previously described bacteriocinogenic strains of Proteus mirabilis and Proteus vulgaris were investigated. All proteocine preparations were particulate, unaffected by trypsin, and destroyed by freezing and thawing or by heating at 60 degrees C for 30 minutes. Proteocine activity was removed by adsorption with the appropriate sensitive organisms. The active principles of all preparations were partially purified by precipitation with 70% (w/v NH4(SO4)2 followed by ultra-centrifugation. Column chromatography showed that proteocine activity was associated with only one of the peaks of material which absorbed strongly at 257 mu. All twelve proteocine preparations were revealed by electron microscopy as a phage-tail-like structure and each particle had a sheath, a core, and a base-plate from which spine-like fibres extend. Adsorption of these particles to the cell wall of sensitive strains did not disrupt the bacterial cell wall, but the cytoplasmic membrane and the cell contents shrank, with consequent death of the "infected" cell.