Date of Award
Master of Science (MS)
Harry D. Kurtz Jr.
Iron (Fe) is the fourth most abundant element in the Earth’s crust and is an essential component in many biological processes. While highly abundant, free iron is not readily available to biological systems since most iron is present in the earth’s crust in the form of ferrous (Fe2+) and ferric (Fe3+) iron minerals. Because of this limited availability, bacteria, plants and fungi have developed diverse ways to safely assimilate and store iron. Bacteria and some fungi have the ability to dissimilate iron. Dissimilatory iron reduction (DIR) is where Fe3+ is reduced to Fe2+ without the cell assimilating the Fe2+ and organisms capable of DIR have been associated with a variety of bioremediation processes.
DIR has been characterized in many bacteria but has not been well studied in fungi. Recently a microbe, HKRS030, was isolated from a sandstone sample from the Grand Staircase Escalante National Monument (GSENM) and was identified as a member of the fungal genus Exophiala. HKRS030 was observed to reduce iron in a dissimilatory fashion, and had its genome sequenced. Later tests found that Exophiala oligosperma, E. jeanselmei, and E. lecanii-corni were capable of DIR as well. When compared to HKRS030, these other members reduced iron to a lesser extent and were observed to have fewer iron reduction related genes present. Their ability to reduce iron in the presence of nitrate was tested, with HKRS030 showing a minimal decrease in iron reduction, while E. oligosperma saw nearly complete inhibition of iron reduction in the presence of nitrate. Due to these genomic and physiological difference it is proposed that Exophiala HKRS030 is a new species in the genus.
Burton, Zachary, "Investigation of Dissimilatory Iron Reduction by Exophiala HKRS030" (2021). All Theses. 3964.