Growth-factor-dependent strains of Salmonellae.

Most strains of Salmonellae have simple nutritional requirements and grow well, therefore, in simple media consisting of glucose, inorganic nitrogen, and mineral salts (Kauffmann, 1954). There are, however, a number of Salmonellae which are unable to synthesize certain essential vitamins and amino acids and these must be supplied in the culture medium. The need of Salmonella typhosa for tryptophan (Fildes et al., 1933), of Salmonella gallinarum for vitamin B1, and of Salmonella pullorum for nicotinic acid, leucine, aspartic acid, cystine, and other amino acids (Johnson and Rettger, 1943; Gilfillan et al., 1955) has been described. Also, Lederberg (1947) has reported strains of Salmonella paratyphi A, S. paratyphi B, S. choleraesuis, S. enteritidis, S. dublin, and S. typhimurium which require for growth different combinations of vitamin B1, biotin, and a variety of amino acids. Different strains of the same serotype may or may not require these growth factors. In the course of our investigations of Salmonellae which develop slowly on ordinary culture media (Stokes and Bayne, 1957, 1958) we have had occasion to determine the specific growth factor requirements of a number of nutritionally dependent strains of Salmonella typhisuis, S. abortusovis, S. fulica, S. paratyphi A, S. pullorum, and S. gallinarum. The results which are reported in the present paper extend the list of growth factor dependent types of Salmonellae and disclose the existence of types with more complex requirements than any previously described.