Evidence that the potential for dissimilatory ferric iron reduction is widespread among acidophilic heterotrophic bacteria

Abstract

Nineteen characterized strains and isolates of acidophilic heterotrophic bacteria were screened for their abilities to catalyse the reductive dissolution of the ferric iron mineral schwertmannite, under oxygen-limiting conditions. Acidocella facilis, Acidobacterium capsulatum, and all of the Acidiphilium, Acidocella and Acidobacterium-like isolates that grew in liquid cultures were able to reduce iron. In contrast, neither Acidisphaera rubrifaciens nor three Acidisphaera-like isolates tested were found to have the capacity for dissimilatory iron reduction. One of two iron-oxidizing Frateuria-like isolates also reduced iron under oxygen-limiting conditions. Microbial dissolution of schwertmannite was paralleled with increased concentrations of soluble ferrous iron and sulfate in microbial cultures, together with increased pH values and decreased redox potentials. While dissimilatory ferric iron reduction has been described previously for Acidiphilium spp., this is this first report of this capacity in Acidocella and the moderate acidophile Acidobacterium. The finding has significant implications for understanding of the biogeochemistry of acidic environments.

Distinct Anaerobic Bacterial Consumers of Cellobiose-Derived Carbon in Boreal Fens with Different CO 2 /CH 4 Production Ratios

“…The labeled taxa in the oligotrophic peat included Holophagaceae and Anaeromyxobacter (Deltaproteobacteria) with members able to reduce HS analogue anthraquinone-2,6-disulfonate (AQDS) (72). None of the labeled taxa resembled known sulfate reducers but instead contained several potential Fe(III) reducers: Rhizomicrobium, Clostridia related to Clostridium saccharobutylicum, and Acidobacteria of groups 1 and 3 (73)(74)(75). Fermentative Fe(III) reducers have been shown to occur in an acidic fen (76).…”

Geomicrobiology of La Zarza-Perrunal Acid Mine Effluent (Iberian Pyritic Belt, Spain)

“…The changes in the microbial diversity of this effluent were mainly determined by analysis using an oxygen gradient. Within the mine portal, conditions are anoxic, so in the first section of the effluent the microorganisms involved in the various chemical reactions must be anaerobic (obligate or facultative) sulfur-and iron-reducing microorganisms (12,19). At the LZ1 station, the presence of oxygen generated by the photosynthetic biofilms, together with the atmospheric oxygen diffusing throughout the water column, favors the appearance of iron-and sulfur-oxidizing microorganisms ( Fig.…”

Microbial reduction of iron and porewater biogeochemistry in acidic peatlands

“…Surprisingly, no PCR products of Anaeromyxobacter, or Shewanella related species were obtained from the lowland fen, although microorganisms from these genera are common to various metal-reducing environments. Recently it was shown that Acidobacterium capsulatum is capable of Fe(III) reduction in a pH range of 2 to 5 (Blöthe et al, 2008) and that the potential for dissimilatory Fe(III) reduction is widespread among acidophilic heterotrophic bacteria (Coupland and Johnson, 2008). Acidobacteria are present in peatlands (Dedysh et al, 2006) and have been detected also in the upland fen of this catchment (Schmalenberger et al, 2008).…”