Geoalkalibacter subterraneus sp. nov., an anaerobic Fe(III)- and Mn(IV)-reducing bacterium from a petroleum reservoir, and emended descriptions of the family Desulfuromonadaceae and the genus Geoalkalibacter.

A strictly anaerobic Fe(III)-reducing bacterium, designated strain Red1(T), was isolated from the production water of the Redwash oilfield, USA. The cells were motile rods (1-5x0.5-0.6 microm) that stained Gram-negative and possessed polar flagella. Strain Red1(T) obtained energy from the reduction of Fe(III), Mn(IV), nitrate, elemental sulfur and trimethylamine N-oxide in the presence of a wide range of electron donors, including a variety of organic acids, alcohols, biological extracts and hydrogen. Strain Red1(T) was incapable of fermentative growth. The novel isolate grew optimally at 40 degrees C (temperature range for growth, 30-50 degrees C) and at pH 7 (pH range, 6-9) with 2 % (w/v) NaCl (NaCl range, 0.1-10 %, w/v). The DNA G+C content was 52.5 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain Red1(T) was a member of the order Desulfuromonadales within the class Deltaproteobacteria and most closely related to Geoalkalibacter ferrihydriticus Z-0531(T) (95.8 %), Desulfuromonas palmitatis SDBY1(T) (92.5 %) and 'Desulfuromonas michiganensis' BB1 (92.4 %). On the basis of phenotypic and phylogenetic differences, the novel strain is proposed to represent a novel species, Geoalkalibacter subterraneus sp. nov. (type strain Red1(T)=JCM 15104(T)=KCTC 5626(T)).