Characterizing Fe(III) Transformation in a Deep-Sea Hyperthermophilic Archaeon
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Hyperthermophilic bacteria and archaea found in deep-sea hydrothermal ecosystems thrive in the chemical disequilibrium and high temperatures found in these environments, growing optimally between 80-110°C. These organisms flourish without the use of energy from the sun, instead utilizing the chemical-rich fluid released from hydrothermal venting structures for energy through chemosynthesis. The subject of this thesis is a recent archaea isolate from a venting structure in the Endeavour Segment of the Juan de Fuca Ridge in the Northeastern Pacific Ocean. The organism is officially known as Strain Su06, but nicknamed “Sully” after the hydrothermal structure from which it was extracted, as it is so newly discovered that it has yet to be given a scientific name or even be assigned a genus. It is a known iron-reducer, utilizing iron oxides for energy through the metabolic process of dissimilatory iron reduction, and is thought to belong to one of two hyperthermophilic archaeal genera; Pyrodictium or Hyperthermus. In this study, we investigated Sully by determining its growth rates under different conditions through ferrozine assays to measure Fe(II) production, and epifluorescence microscopy to determine cell concentration, in order to establish optimal growth temperature for the species. Cell characteristics and iron-cell contact were visualized through electron microscopy. The findings were then compared to species within the Pyrodictium and Hyperthermus genera in order to get closer to answering the question of which it belongs to. The study of extremophilic archaea is fundamentally based in concepts of astrobiology. Because of their archaic nature and ability to exist at high temperatures, it is thought that similar organisms may have been spread throughout the solar system after heavy impacts or may be closely related to our last universal common ancestor. Additionally, the scientific investigation of iron-reducers’ metabolic pathways is of interest in the study of biofuels. Gaining a further understanding of geothermal environments may lead to future sustainable energy resources.