Identifying Genes Involved in the Iron Metabolism Pathway Through Transcriptomic Analysis

Iron oxidizing bacteria are important to the biological iron cycle but the mechanism of Fe-oxidation is poorly understood. TAG-1 is a new isolate that grows on both Fe(II) and H₂, thus can be used for transcriptomic analysis of gene expression involved in iron metabolism. The actB1 gene encodes for a component of alternative complex III (ACIII), which functionally replaces cytochrome bc₁/b₆f of the electron transport chain. We hypothesized if ACIII is involved in iron metabolism, then actB1 expression will be higher in TAG-1 cells grown on Fe(II) than H₂. TAG-1 was grown on zero valent iron (ZVI) and H₂ gas and direct cell counts were used to determine substrate preference. TAG-1 cells consistently grew more on ZVI. ActB1 gene expression was determined via quantitative PCR and compared to the housekeeping gene recA. ActB1 gene expression was higher in TAG-1 grown on ZVI after 48, 72, and 96 hour time points. The recA gene failed to amplify despite the use of various primers. We conclude that ActB1 was expressed in the presence of both substrates indicating a poor biomarker for Fe-oxidation.