Thermofilum pendens Hrk 5

Thermofilum pendens (strain Hrk5) is a a sulfur-dependent, anaerobic heterotroph archaea. It forms long thin filaments and may have an unusual mode of reproduction in which spherical bulges form at one end of the cell. It is an extracellular commensal, requiring an extract of another crenarchaeota Thermoproteus tenax for growth, and the genome sequence reveals that biosynthetic pathways for purines, most amino acids, and most cofactors are absent. Besides the lack of biosynthesis, several nutrient transporters that are not found in any other crenarchaeote are present in T. pendens. It appears that T. pendens has adapted to life in an environment rich in nutrients and grows mainly by peptide fermentation. It was known previously to utilize peptides as an energy source, but the genome revealed a substantial ability to grow on carbohydrates. T. pendens may obtain energy from sulfur reduction with hydrogen and formate as electron donors. It may also be capable of sulfur-independent growth on formate with formate hydrogen lyase. (HAMAP: THEPD)