The typing of nocardia pellegrini with different nocardia-phages was studied. The investigation included 25 nocardia pellegrini strains, 19 strains of different nocardia species and also strains of different species of mycobacteria. It could be stated that phages typical for nocardia pellegrini were also active against other fast fragmentating nocardia species, such as nocardia corallina or nocardia rubra. However, they did not attack nocardia asteroides or strains of mycobacteria. Phages typical for mycobacteria or for nocardia asteroides did not lysate the fast fragmentating nocardia (Table 1 and 2). Mutants of one nocardia pellegrini phage could be isolated which showed a broader host range than the parent phage (Table 1 and 2). Some lysogenic strains of nocardia pellegrini with a changed phage sensitivity could be isolated after action of the phages (Table 3). The taxonomical position of nocardia pellegrini and nocardia rubra is discussed.
