RESUMO
The sensitivity of four strains of Sh. dysenteriae and of nine strains representing other serotypes of Sh. dynsenteriae to phages T2, T4 and T6 was examined. Different extracts, prepared from sensitive strains were tested for their capacity of phage inactivation. We found that the receptor substance for phage T2 is localized differently in various strains: In Sh. dysenteriae 7, it was found in bacterial extracts obtained by water/phenol at 68 degrees C and in extracts obtained by trichloracetic acid; in Sh. dysenteriae 2 and Sh. dysenteriae 6, it was found in extracts obtained by heating in water at 65 degrees C. None of the tested extracts of strains Sh. dysenteriae 1, Sh. dysenteriae 4 and Sh. dysenteriae 9, sensitive to phage T2 and T6 and T6, revealed receptro activity for these phages. Most of the extracts, which showed receptor activity for phage T2, appeared to be weak or completely inactive for phage T6. Several strains appeared to be sensitive to phage T4 and the receptor active substance was found in the bacterial extracts obtained by water/phenol at 68 degrees C. The sensitivity of Sh. dysenteriae smooth strains to "rough specific" T4 phage is discussed.