Understanding the Community Composition of Deep Sea Iron-Oxidizing Bacteria, Zetaproteobacteria, in the Estuary of Charleston, SC

The deep ocean hydrothermal vents are a source of high amounts of iron. Zetaproteobacteria are the only known organisms to oxidize iron near the vents under nearly neutral pH conditions. Recent research has identified these bacteria in a wide range of habitats, including the oxic-anoxic transition zone of the Chesapeake Bay estuary, and on carbon steel. The Charleston estuary and salt marshes serve as a transition zone between marine and freshwater environments and provide a potential area for Zetaproteobacteria to grow. The goals of this study are to identify areas in the Charleston estuary where Zetaproteobacteria are present, observe the impact that salinity gradients may have on their community composition, and assess their potential to colonize mild steel in a coastal salt marsh environment. Sediment samples were collected at low tide across sites from the Stono, Ashley, Wando, and Cooper rivers of Charleston, South Carolina. In-situ dissolved oxygen, temperature, and salinity were recorded at all sites. In addition, iron (II) and total iron were measured using a ferrozine assay. As the second component of this study, Microbial Iron-Oxidation Chambers (MIOCs) were constructed with small steel coupons and submerged in the same location as the sampling sites. The preliminary PCR analysis suggests Zetaproteobacteria are present in Charleston and can colonize steel within the salt marsh, however exact abundances must be calculated using qPCR. Sequencing of the DNA obtained from the steel coupons and sediment will further allow for delineation of Zetaproteobacteria community composition. Identifying how these bacteria grow in areas of varying salinity will allow for a better understanding of the changes in iron-oxidizing bacterial communities over space and time and how they impact the global iron cycle.