Characterization of two Idiomarina sp. isolated from cathodes and capable of solid substrate oxidation

By Jorge Vinales, Biomedical Studies Advisor: Annette Rowe Presentation ID: AM_ATRIUM12 Abstract: The transfer of electrons to and from solid-substrates and cells, a process termed extracellular electron transport (EET), has remodeled our understanding of microbial physiology as well as the potential for technologies at the microbe-electric interface. While many mineral-reducing organisms have been described, very few mineral-oxidizing organisms have been characterized and as such, this metabolism is poorly understood. Specifically, very few genes or mechanisms are known related to oxidative-EET. To better understand oxidative-EET, we isolated a variety of microbes on cathodes incubated in marine sediment taken from Catalina Island. Negative current production at -200 mV vs. SHE was sustained in sediments for up to four weeks, and biomass from these reactors was used to isolate microbes capable of solid substrate oxidation (predominantly, of iron and sulfur minerals). This work focuses on the characterization of two of the strains isolated that display unique electron uptake characteristics on cathodes. Phylogenetic analysis of the 16S rRNA gene of strains SN11and FeNw1 show them belonging to the genus Idiomarina. Culturing methods have included using carbohydrates, amino acids, and sulfur species as electron donors. Further characterization across cathode isolates and the type strains of Idiomarina will investigate the ability of the organisms to grow on electrodes, inorganic minerals, and using alternate terminal electron acceptors (i.e. nitrate). The unique electrochemical activity observed in Idiomarina sp. along with its relatively small genome (~2 Mb) and small number of cytochromes (