Quantifying iron oxidase expression in microcosm experiments with RT-qPCR

• Christopher Blanda, Biochemistry, University of Delaware

• Clara Chan, Earth Sciences, University of Delaware

Bacteria that oxidize iron in the environment can function as natural filters because the iron oxyhydroxides they produce can bind nutrients and contaminants. At the Savannah River Site in South Carolina there are large iron mats containing many iron oxidizers, including Leptothrix spp.and Leptothrix ochracea. These organisms are important to the geochemistry of the area because they create iron sheaths as they grow in the environment, ligating heavy metals such as uranium at the Savannah River Site. These organisms act as a natural filter for the environment and also help cycle iron and carbon, which is important because of the potential applications to environmental remediation. In order to better understand these processes we need a better understanding of the microbial metabolisms involved. Previous research has shown the iron oxidase genes cyc2 and mtoA respond to the presence of iron. However, their expression level in the environment is unknown at the SRS for Leptothrix spp.and Leptothrix ochracea. The goal of this project is to quantify the expression of iron oxidase genes cyc2 and mtoA in Leptothrix ochracea and Leptothrix spp. using RT-qPCR. This method will use RNA extracted in a time series experiment where Fe²⁺ was added to iron mats suspended in water from the SRS. The goal of using this RNA is to see iron gene expression at different time points. The results will inform us if cyc2 and mtoA are indeed expressed in response to iron stimulation. This will give us novel insight into the metabolism of Leptothrix spp.and Leptothrix ochracea. Furthermore once the metabolism is better understood environmental interactions can be studied to a higher degree.