Purine requiring strains of Shigellae.

The importance of growth factors in the nutrition of shigellae was recognized by Koser and Saunders (1935) and it was shown that the growth factors present in tissue extract could be replaced by nicotinic acid (Koser et al., 1938). The importance of nicotinic acid and nicotinamide as growth factors in the nutrition of shigellae has been shown by Dorfman et al. (1939). Reports of other vitamins as essential requirements are to be found in the literature (Weil and Black, 1944; Bernheimer, 1946). In the course of an investigation into the nutritional requirements of members of the genus Shigella (Sen, 1959), two strains of Shigella boydii were found to have specific growth requirements for purine derivatives.