Acidibacter ferrireducens gen. nov., sp. nov. an acidophilic ferric iron-reducing gammaproteobacterium

Carmen Falagán*, D. Barrie Johnson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


An acidophilic gammaproteobacterium, isolated from a pit lake at an abandoned metal mine in south-west Spain, was shown to be distantly related to all characterized prokaryotes, and to be the first representative of a novel genus and species. Isolate MCF85 is a Gram-negative, non-motile, rod-shaped mesophilic bacterium with a temperature growth optimum of 32–35 °C (range 8–45 °C). It was categorized as a moderate acidophile, growing optimally at pH 3.5–4.0 and between pH 2.5 and 4.5. Under optimum conditions its culture doubling time was around 75 min. Only organic electron donors were used by MCF85, and the isolate was confirmed to be an obligate heterotroph. It grew on a limited range of sugars (hexoses and disaccharides, though not pentoses) and some other small molecular weight organic compounds, and growth was partially or completely inhibited by small concentrations of some aliphatic acids. The acidophile grew in the presence of >100 mM ferrous iron or aluminium, but was more sensitive to some other metals, such as copper. It was also much more tolerant of arsenic (V) than arsenic (III). Isolate MCF85 catalysed the reductive dissolution of the ferric iron mineral schwertmannite when incubated under micro-aerobic or anaerobic conditions, causing the culture media pH to increase. There was no evidence, however, that the acidophile could grow by ferric iron respiration under strictly anoxic conditions. Isolate MCF85 is the designated type strain of the novel species Acidibacter ferrireducens (=DSM 27237T = NCCB 100460T).

Original languageEnglish
Pages (from-to)1067-1073
Number of pages7
Issue number6
Early online date13 Aug 2014
Publication statusPublished - 1 Nov 2014


  • Acidibacter ferrireducens
  • acidophile
  • Gammaproteobacteria
  • heterotroph
  • iron reduction


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