Effect of iron on production of a possible virulence factor by Plesiomonas shigelloides

Plesiomonas shigelloides, when grown in an iron-poor medium (syncase), produces a substances that causes elongation of Chinese hamster ovary (CHO) cells similar to that produced by cholera toxin. When syncase is supplemented with iron, the ability of P. shigelloides (but not of Vibrio cholerae) to produce this elongation of CHO cells is lost. Iron depletion of the growth medium appears to be essential for the CHO cell elongation produced by P. shigelloides but is not essential for the production of toxin by V. cholerae. The possible role of iron regulation of this potential virulence factor warrants further study.