Phage and bacteriocin receptor activity of a proteus vulgaris strain

Abstract

Two hundred and sixty three Dienes incompatible strains of Proteus vulgaris were examined for the ability to produce bacteriocins active on Proteus vulgaris strain 69. This strain is the host organism in a transduction system utilizing a P. vulgaris generalized transducing phage, 0107/69. Substances inhibitory for P. vulgaris strain 69 were obtained from twelve of the P. vulgaris strains upon induction by ultraviolet irradiation or Mitomycin C treatment. Electron microscopy of the active principle from the 12 inhibitor strains revealed the presence of phgge-tail-like structures morphologically similar to the tail of phage 107/69. Fifty mutants of strain 69 were selected for resistance towards each of the 12 bacteriocins obtained. All 50 x 12 bacteriocin-resistant mutants displayed simultaneous resistance towards the transducing phage 107/69. A number of mutants of strain 69 selected for resistance to phage 107/69 exhibited a similar cross-resistance towards all 12 bacteriocins. The bacteriocins could be classified into 2 groups on the basis of activity patterns on many mutants of strain 69 and on numerous other strains of P. vulgaris, P. mirabilis, P. morganii and Serratia marcescens. Although all the bacteriocins were found to be morphologically similar, they were also classifiable serologically into the same 2 groups. A weak serological relationship was observed between the 2 groups of bacteriocins and phage 107/69. The 12 bacteriocins are similar in another way. They all induce phage 107/69 development in P. vulgaris strain 107. This phenomenon which has been encountered with colicins and megacins was not further investigated. It is concluded that the P. vulgaris phage-tail-like bacteriocins may represent the products of defective lysogeny, and that the members of the 2 groups and phage 107/69 adsorb to non-identical but closely linked receptor sites on the sensitive cell's surface.