Samples were dried and treated with 3 M nitric acid overnight at room temperature then quickly boiled. Total manganese content was determined by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) at North Carolina State University Analytical Service Laboratory. Total manganese and iron was measured Kinase Inhibitor Library mouse in LB medium as above using a 5X concentration of medium. Results Growth of Δfur under anaerobic and aerobic conditions Iron is an essential element for redox reactions in biology. However, it is an important factor in oxygen toxicity due to its involvement in hydroxyl radicals (HO·)

formation via Fenton chemistry [57]. Therefore, we compared the effects of a deletion of fur on growth kinetics under both anaerobic and aerobic conditions. Data in Figure 1 demonstrate that Δfur was not compromised in its growth kinetics under either anaerobic or aerobic conditions. Figure 1 Growth kinetics of Δ fur (black square compared to 14028s (white square). Selleck Z-IETD-FMK Cells were grown in LB-MOPS-X medium as described in Methods; (A) Anaerobic growth; (B) Aerobic growth. Effect of Fur on the anaerobic transcriptome of S. Typhimurium Under anaerobic conditions, the absence of fur resulted in the differential

expression of 298 genes (Additional File 2: Table S2). These genes were organized by Cluster of Orthologous Groups (COGs) and the numbers of genes within each COG are shown in Table 2. The absence of fur resulted in increased expression (i.e., Fur acted as a repressor) of 226 genes. However, the absence of Fur resulted in decreased expression (i.e., Fur acted as an activator) of 72 genes, most likely via an indirect mechanism. Table 2 Number of Differentially Expressed Genes in Δfur Differentially Expressed Genes in Δfur Cluster of Orthologous Groups Number of Genes “”Fur Repressed”" a Number

of Genes “”Fur Activated”" b Total No COG 30 9 39 Energy Production and Conversion 16 18 34 Cell Cycle Control 3 0 3 Amino Acid Metabolism and Transport 7 16 23 Nucleotide Metabolism and Transport 7 4 11 Carbohydrate Metabolism and Transport 9 4 13 Coenzyme Metabolism and Transport 6 0 6 Lipid Metabolism and Transport 5 0 5 Translation 46 0 46 Transcription 9 2 11 Replication, Recombination, and Repair 5 1 6 Cell Wall/Membrane/Envelope Biogenesis 14 3 17 Cell Motility 1 0 1 Post-Translational Modification, old Protein Turnover, Chaperone Functions 10 1 11 Inorganic Ion Transport and Metabolism 20 2 22 Secondary Metabolite Biosynthesis, Transport, and Catabolism 5 4 9 General Functional Prediction Only 15 4 19 Function Unknown 9 2 11 Signal Transduction Mechanisms 5 2 7 Intracellular Trafficking and Secretion 3 0 3 Defense Mechanisms 1 0 1 Total 226 72 298 Categorized According to Cluster of Orthologous Groups (COGs) a Genes with increased expression in the absence of fur b Genes with decreased expression in the absence of fur A Fur information matrix, specific for S.