Effect of iron limitation on the growth and cytotoxin production of Salmonella choleraesuis SC-5

This study investigated the effect of iron limitation on the growth and cytotoxin production of Salmonella choleraesuis and examined the iron-accruing capability of various Salmonella strains. It was found that the growth of S. choleraesuis SC-5 was retarded by the presence of iron-chelating agents, 2,2'-dipyridyl or ethylenediamine di-o-hydroxyphenylactic acid (EDDA). Addition of 2,2'-dipyridyl to Trypticase soy broth (TSB) resulted in a smaller maximum population of S. choleraesuis noted at the stationary phase, while addition of EDDA in TSB only caused an extended period of lag phase. A significant increase in cytotoxin production was found when S. choleraesuis SC-5 was cultured in iron-limited TSB containing 2,2'-dipyridyl. On the other hand, pre-culture in an iron-limited medium increased the growth of S. choleraesuis SC-5 in mouse serum with or without complement inactivated. Testing with a plate assay method revealed that the ability and efficiency of Salmonella to acquire iron under iron-limited condition varied with strains, and the kinds and dosages of iron-containing compounds present. (C) 2003 Published by Elsevier B.V.