LExEn: Diversity of Electron Donors and Electron Acceptors Supporting the Growth of Hyperthermophilic Microorganisms.

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

0085365 Lovely Microorganisms are thought to have an important impact on the geochemistry of hot (80-110 degrees C), oxygen-depleted environments such as those found deep below the Earth's surface, at the bottom of the ocean, and around terrestrial hot springs. The goal of this research is to evaluate the metabolic diversity of anaerobic hyperthermophilic microorganisms in order to learn more about the biogeochemical processes that are possible in hot microbial ecosystems. It is hypothesized that there is wide diversity of microorganisms that are capable of living in hot environments by oxidizing organic compounds such as: acetate and other short-chain fatty acids, long-chain fatty acids, amino acids, aromatic compounds, and a variety of hydrocarbons. Electron acceptors for the oxidation of these organic compounds are predicted to include Fe(III), sulfate, S (zero), or nitrate. It is proposed that in the absence of these electron acceptors that these organic compounds can be microbially converted to methane. Novel strategies will be employed in an attempt to recover autotrophic, hydrogen-oxidizing, Fe(III)-reducing hyperthermophiles because it is hypothesized that some organisms with this form of respiration will phylogenetically be among the most deeply branching microorganisms still existing on Earth. In order to evaluate the possibility that Fe(III) reducers may be active in hot, acidic environments, an attempt will be made to recover acidophilic hyperthermophiles that can reduce the soluble Fe(III) found at low pH. The possibility that Fe(III)-reducing hyperthermophiles produce isotopically unique Fe(II) minerals will be evaluated by examining the oxygen and iron isotopes in these minerals. It is expected that these studies will provide further insight into the biology and geology of hot microbial ecosystems on Earth as well as the microbial ecosystems that may exist in the hot subsurface of other planets. These studies are also expected to have economic benefits by: 1) better explaining the generation of economically important ore deposits; 2) providing new strategies for the remediation of toxic organic and metal contaminants; and 3) suggesting a new approach for increased recovery of hydrocarbons from petroleum reservoirs.