COLICIN‐LIKE ANTIBIOTICS OF 100 STRAINS OF SALMONELLA

Summary The colicin‐like antibiotics of 100 strains of Salmonella (here called ‘salcols’) were divided into four groups. Group 1 was the largest (78 members) and was related to colicins I and SI but showed at least two subgroups. Group 2 was related to colicins E and F and had four members. Group 3 contained several weak salcols of uncertain relationship to other salcols and colicins and was heterogeneous, although having some reactions in common with group 1, Group 4 contained one salcol which was diffusible through cellophane and had some resemblances to colicins V and B. These four groups were defined by inhibition zone characters, diffusibility and activity range on resistant or producer strains and on various strains of Salmonella ; they were compared directly with known colicins.