Geobacter pickeringii sp. nov., Geobacter argillaceus sp. nov. and Pelosinus fermentans gen. nov., sp. nov., isolated from subsurface kaolin lenses

Abstract

The goal of this project was to isolate representative Fe(III)-reducing bacteria from kaolin clays that may influence iron mineralogy in kaolin. Two novel dissimilatory Fe(III)-reducing bacteria, strains G12T and G13T, were isolated from sedimentary kaolin strata in Georgia (USA). Cells of strains G12T and G13T were motile, non-spore-forming regular rods, 1–2 μm long and 0.6 μm in diameter. Cells had one lateral flagellum. Phylogenetic analyses using the 16S rRNA gene sequence of the novel strains demonstrated their affiliation to the genus Geobacter. Strain G12T was most closely related to Geobacter pelophilus (94.7 %) and Geobacter chapellei (94.1 %). Strain G13T was most closely related to Geobacter grbiciae (95.3 %) and Geobacter metallireducens (95.1 %). Based on phylogenetic analyses and phenotypic differences between the novel isolates and other closely related species of the genus Geobacter, the isolates are proposed as representing two novel species, Geobacter argillaceus sp. nov. (type strain G12T=ATCC BAA-1139T=JCM 12999T) and Geobacter pickeringii sp. nov. (type strain G13T=ATCC BAA-1140T=DSM 17153T=JCM 13000T). Another isolate, strain R7T, was derived from a primary kaolin deposit in Russia. The cells of strain R7T were motile, spore-forming, slightly curved rods, 0.6×2.0–6.0 μm in size and with up to six peritrichous flagella. Strain R7T was capable of reducing Fe(III) only in the presence of a fermentable substrate. 16S rRNA gene sequence analysis demonstrated that this isolate is unique, showing less than 92 % similarity to bacteria of the Sporomusa–Pectinatus–Selenomomas phyletic group, including ‘Anaerospora hongkongensis’ (90.2 %), Acetonema longum (90.6 %), Dendrosporobacter quercicolus (90.9 %) and Anaerosinus glycerini (91.5 %). On the basis of phylogenetic analysis and physiological tests, strain R7T is proposed to represent a novel genus and species, Pelosinus fermentans gen. nov., sp. nov. (type strain R7T=DSM 17108T=ATCC BAA-1133T), in the Sporomusa–Pectinatus–Selenomonas group.

Ferrihydrite-associated organic matter (OM) stimulates reduction by <i>Shewanella oneidensis</i> MR-1 and a complex microbial consortia

“…These bacteria can use H 2 as an electron donor and acetate as a carbon source, and are also capable of fermenting citrate, lactate, and organic impurities. Pelosinus has also been shown to reduce small concentrations of anthraquinone-2.6-disulfonate (AQDS), a synthetic quinone, in the presence of citrate or lactate (Shelobolina et al, 2007). The ability of these microorganisms to use AQDS as an electron sink under reducing conditions might explain their enrichment during our incubations.…”

“…Pelosinus spp. have been characterized as fermentative bacteria which utilize Fe(III) as an electron sink (Shelobolina et al, 2007). These bacteria can use H 2 as an electron donor and acetate as a carbon source, and are also capable of fermenting citrate, lactate, and organic impurities.…”

Geobacter uraniireducens sp. nov., isolated from subsurface sediment undergoing uranium bioremediation

“…The 16S rRNA gene was amplified as described previously (Shelobolina et al, 2007b). The 16S rRNA gene sequence of strain Rf4 T had 97.3-99.2 % similarity to Geobacter sequences 14o40, 27o254 and 34o239 found in a 16S rRNA gene clone library from groundwater taken at the same time as the source sediment (Fig.…”

“…Physiological characteristics were determined by previously described methods (Shelobolina et al, 2007b). Results are given in the species description.…”

Draft Genome Sequences for Two Metal-Reducing Pelosinus fermentans Strains Isolated from a Cr(VI)-Contaminated Site and for Type Strain R7

“…elosinus fermentans strain R7 was isolated as a representative iron-reducing bacterium from Russian kaolin clays and as the type strain for a new genus (11). P. fermentans 16S rRNA gene sequences dominated iron-reducing enrichments derived from geochemically different soils obtained from the Melton Branch Watershed, near Oak Ridge, TN, which suggests physiological flexibility within the species (4).…”