3 items with the tag “volcanic

  • Chemolithotrophic Microbial Oxidation of Insoluble Fe(II)-Bearing Minerals
    NAI 2009 University of Wisconsin Annual Report

    Ferrous iron (Fe(II)) can serve as an energy source for a wide variety of chemolithotrophic microorganisms (organisms that gain energy from metabolism of inorganic compounds). Thought to be one of the oldest forms of microbial metabolism on Earth, Fe(II) oxidation may also have played a role in past (and possibly, present) life on Mars, whose crust is rich in Fe(II)-bearing silicate minerals (e.g. ultramafic basalt rocks). The initial goal of this project is to determine whether an established chemolithoautotrophic Fe(II)-oxidizing, nitrate-reducing culture can grow by oxidation of Fe(II) in basalt glass. Preliminary experiments suggest that the culture is able to oxidize a significant portion of the Fe(II) content of fresh basalt glass from Kilauea, a shield volcano in Hawaii that represents an analog for ancient volcanic activity on Mars.

    ROADMAP OBJECTIVES: 4.1 6.1 7.1
  • Project 2A: Chemolithotrophic Microbial Oxidation of Basalt Glass
    NAI 2010 University of Wisconsin Annual Report

    Ferrous iron (Fe(II)) can serve as an energy source for a wide variety of chemolithotrophic microorganisms (organisms that gain energy from metabolism of inorganic compounds). Fe(II) oxidation may have played a role in past (and possibly, present) life on Mars, whose crust is rich in Fe(II)-bearing silicate minerals (e.g. ultramafic basalt rocks). The goal of this project is to determine whether an established chemolithoautotrophic Fe(II)-oxidizing, nitrate-reducing culture can grow by oxidation of Fe(II) in basalt glass. Experiments showed that the culture is able to oxidize a significant portion (approximately 1%) of the Fe(II) content of fresh basalt glass from Kilauea, a shield volcano in Hawaii that represents an analog for ancient volcanic activity on Mars. The ratio of Fe(II) oxidized to nitrate reduced was consistent with the expected 1:5 stoichiometry, suggesting that the culture oxidized Fe(II) with nitrate in a manner analogous to its metabolism of other (e.g. aqueous) Fe(II) forms.

    ROADMAP OBJECTIVES: 2.1 6.2 7.1
  • Project 2F: Potential for Lithotrophic Microbial Oxidation of Fe(II) in Basalt Glass
    NAI 2012 University of Wisconsin Annual Report

    Ferrous iron (Fe(II)) can serve as an energy source for a wide variety of chemolithotrophic microorganisms (organisms that gain energy from metabolism of inorganic compounds). Fe(II) oxidation may have played a role in past (and possibly, present) life on Mars, whose crust is rich in primary Fe(II)-bearing silicate minerals, as well as Fe-bearing clay minerals formed during weathering of primary silicates. This project examined the potential for microbial oxidation of Fe(II) in basaltic glass. Recent research suggests that near‐surface hydrothermal venting may have occurred during past periods of active volcanic/tectonic activity on Mars. Such activities could have produced basalt glass phases that might have served as energy sources for chemolithotrophic microbial activity. Previous and ongoing NAI‐supported studies have shown that an established chemolithoautotrophic Fe(II)‐oxidizing, nitrate‐reducing culture can grow by oxidation of Fe(II) insoluble Fe(II)‐bearing phyllosilicate phases such as biotite and smectite. The initial goal of this project was to determine whether or not this culture is capable of oxidizing Fe(II) in basalt glass. In addition we tested basaltic glass oxidation by a culture of Desulfitobacterium frappieri, as previous studies demonstrated that D. frappieri is capable of nitrate-dependent oxidation of structural Fe(II) in smectite. Finally, in situ and enrichment culturing experiments were conducted to determine whether indigenous Fe(II)-oxidizing organisms in a groundwater iron seep were capable of colonization and oxidation of basaltic glass. The results of these experiments showed that while the various cultures were readily capable of smectite oxidation with nitrate, none were able to carry-out significant oxidation of Fe(II) in basalt glass. We speculate that Fe(II) atoms in the amorphous glass are somehow occluded and therefore not accessible to outer membrane cytochrome systems thought to be involved in extracellular Fe(II) oxidation.

    ROADMAP OBJECTIVES: 2.1 5.1 5.3