Geobacter sulfurreducens sp. nov., a hydrogen- and acetate-oxidizing dissimilatory metal-reducing microorganism

Abstract

A dissimilatory metal-and sulfur-reducing microorganism was isolated from surface sediments of a hydrocarbon-contaminated ditch in Norman, Okla. The isolate, which was designated strain PCA, was an obligately anaerobic, nonfermentative, nonmotile, gram-negative rod. PCA grew in a defined medium with acetate as an electron donor and ferric PP1, ferric oxyhydroxide, ferric citrate, elemental sulfur, Co(III)-EDTA, fumarate, or malate as the sole electron acceptor. PCA also coupled the oxidation of hydrogen to the reduction of Fe(III) but did not reduce Fe(III) with sulfur, glucose, lactate, fumarate, propionate, butyrate, isobutryate, isovalerate, succinate, yeast extract, phenol, benzoate, ethanol, propanol, or butanol as an electron donor. PCA did not reduce oxygen, Mn(IV), U(VI), nitrate, sulfate, sulfite, or thiosulfate with acetate as the electron donor. Cell suspensions of PCA exhibited dithionite-reduced minus air-oxidized difference spectra which were characteristic of c-type cytochromes. Phylogenetic analysis of the 16S rRNA sequence placed PCA in the delta subgroup of the proteobacteria. Its closest known relative is Geobacter metalireducens. The ability to utilize either hydrogen or acetate as the sole electron donor for Fe(III) reduction makes strain PCA a unique addition to the relatively small group of respiratory metal-reducing microorganisms available in pure culture. A new species name, Geobacter su(furreducens, is proposed.

Humics as an electron donor for anaerobic respiration

“…G. sulphurreducens does not reduce nitrate, but can use fumarate as a terminal electron acceptor (Caccavo et al, 1994). Cell suspensions of G. sulphurreducens exhibited fumarate-dependent AHQDS oxidation ( Fig.…”

Geobacter sp. SD‐1 with enhanced electrochemical activity in high‐salt concentration solutions

“…Only Geobacter sulfurreducens has so far been shown to be able to produce a current comparable to those of mixed cultures, and microorganisms most similar to this species are commonly found to predominate the biofilms of mixed cultures (Bond and Lovley, 2003;Nevin et al, 2008;Call et al, 2009;Torres et al, 2009;Sun et al, 2012). The type strain G. sulfurreducens PCA was first isolated as a dissimilatory metal-reducing bacteria (DMRB) from sediments, and later used in BESs (Caccavo et al, 1994).…”

Chemical property based sequence characterization of PpcA and its homolog proteins PpcB-E: A mathematical approach

“…Firstly, we calculate the percentage of occurrence of amino acids from each chemical group using the following equation Eq (2). If there are n number of sequences which are denoted as S 1 , S 2 , .…”

“…Five homologous triheme cytochromes (PpcA-E) are identified in G. sulfurreducens periplasm and gene knockout studies revealed their involvement in Fe(III) and U(VI) extracellular reduction [1,2]. Cytochromes have been thoroughly studied for laboratory experiments because of their small size (about 90 amino acids).…”

“…Geobacter sulfurreducens is one of the predominant metal and sulphur reducing bacteria [1]. The organism Geobacter sulfurreducens is known to act as an electron donar and participate in redox reaction [2]. Periplasmic c7 type cytochrome A (PpcA) protein along with its four additional homologs (PpcB-E: PpcB, PpcC, PpcD, PpcE) are identified in Geobacter sulfurreducens genome [3][4][5][6].…”