Acidithrix ferrooxidans gen. nov., sp. nov.; a filamentous and obligately heterotrophic, acidophilic member of the Actinobacteria that catalyzes dissimilatory oxido-reduction of iron

Res Microbiol. 2015 Feb-Mar;166(2):111-20. doi: 10.1016/j.resmic.2015.01.003. Epub 2015 Jan 29.


A novel acidophilic member of the phylum Actinobacteria was isolated from an acidic stream draining an abandoned copper mine in north Wales. The isolate (PY-F3) was demonstrated to be a heterotroph that catalyzed the oxidation of ferrous iron (but not of sulfur or hydrogen) under aerobic conditions, and the reduction of ferric iron under micro-aerobic and anaerobic conditions. PY-F3 formed long entangled filaments of cells (>50 μm long) during active growth phases, though these degenerated into smaller fragments and single cells in late stationary phase. Although isolate PY-F3 was not observed to grow below pH 2.0 and 10 °C, harvested biomass was found to oxidize ferrous iron at relatively fast rates at pH 1.5 and 5 °C. Phylogenetic analysis, based on comparisons of 16S rRNA gene sequences, showed that isolate PY-F3 has 91-93% gene similarity to those of the four classified genera and species of acidophilic Actinobacteria, and therefore is a representative of a novel genus. The binomial Acidithrix ferrooxidans is proposed for this new species, with PY-F3 as the designated type strain (=DSM 28176(T), =JCM 19728(T)).

Keywords: Acidophile; Actinobacteria; Iron oxidation; Iron reduction; Novel species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinobacteria / classification*
  • Actinobacteria / cytology
  • Actinobacteria / isolation & purification
  • Actinobacteria / metabolism*
  • Copper
  • Fatty Acids / metabolism
  • Ferric Compounds / metabolism*
  • Ferrous Compounds / metabolism*
  • Heterotrophic Processes
  • Hydrogen / metabolism
  • Mining
  • Oxidation-Reduction
  • Phylogeny
  • RNA, Ribosomal, 16S / genetics
  • Sulfur
  • Wales
  • Water Microbiology


  • Fatty Acids
  • Ferric Compounds
  • Ferrous Compounds
  • RNA, Ribosomal, 16S
  • Sulfur
  • Copper
  • Hydrogen