Supplementary Material for: Prediction and Experimental Testing of Ferric Uptake Regulator Regulons in Vibrios R.Ahmad E.Hjerde G.Å.Hansen P.Haugen N.-P.Willassen 2008 Iron homeostasis is in many bacteria regulated by the ferric uptake regulator (Fur). Despite the available information on Fur regulons, it is likely that there are Fur-regulated genes and operons that are unique to vibrios, and knowledge into these can potentially provide new insights into vibrio virulence and pathogenesis. We constructed a vibrio-specific alignment matrix based on Fur-binding sites from the literature and used existing software (Patser) to search five published vibrio genomes and the <i>Vibrio salmonicida</i> draft genome for Fur-regulated genes. The consensus Fur-binding site from our matrix is 5′-AATGANAATNATTNTCATT-3′. Fur-binding motifs were found associated with 50–61 single genes and 16–20 operons in each genome. Predictions were tested by monitoring the expression of a subset of genes and operons in <i>V. salmonicida</i>. Six previously undescribed Fur-regulated genes showed increased expression under iron-restrictive conditions. Our work provides a comprehensive list of predicted Fur regulons in six vibrio genomes, which may be used to generate new hypotheses for future experiments.