Lithotrophy & Methanogenesis

Lithotrophy & Methanogenesis

1. Some bacteria are "obligate lithotrophs"

   • oxidize only inorganic molecules
   • most lithotrophs are bacteria or archaea that can thrive in ecosystems where eukaryotes cannot

2. 2 important types of lithotrophy

   • N and S Oxidation
     • microbial N and S oxidation can cause severe environmental acidification, eroding structures

3. Hydrogenotrophy

   • Use H2 as an electron donor
     • H2 has reducing potential to donate electrons to nearly all electron acceptors
   • hard to categorize; umbrella term

4. Methanogenesis

   • reduction of carbon dioxide and other single-C compounds to methane
   • many methanogens are chemoautotrophs
     • recently found in cyanobacteria
       • Night: perform methanogenesis Day: photosynthesis
   • simplest form is H reduction of CO2