Thermincola ferriacetica sp. nov., a new anaerobic, thermophilic, facultatively chemolithoautotrophic bacterium capable of dissimilatory Fe(III) reduction

Abstract

A moderately thermophilic, sporeforming bacterium able to reduce amorphous Fe(III)-hydroxide was isolated from ferric deposits of a terrestrial hydrothermal spring, Kunashir Island (Kurils), and designated as strain Z-0001. Cells of strain Z-0001 were straight, Gram-positive rods, slowly motile. Strain Z-0001 was found to be an obligate anaerobe. It grew in the temperature range from 45 to 70 degrees C with an optimum at 57-60 degrees C, in a pH range from 5.9 to 8.0 with an optimum at 7.0-7.2, and in NaCl concentration range 0-3.5% with an optimum at 0%. Molecular hydrogen, acetate, peptone, yeast and beef extracts, glycogen, glycolate, pyruvate, betaine, choline, N-acetyl-D-glucosamine and casamino acids were used as energy substrates for growth in presence of Fe(III) as an electron acceptor. Sugars did not support growth. Magnetite, Mn(IV) and anthraquinone-2,6-disulfonate served as the alternative electron acceptors, supporting the growth of isolate Z-0001 with acetate as electron donor. Formation of magnetite was observed when amorphous Fe(III) hydroxide was used as electron acceptor. Yeast extract, if added, stimulated growth, but was not required. Isolate Z-0001 was able to grow chemolithoautotrophicaly with molecular hydrogen as the only energy substrate, Fe(III) as electron acceptor and CO(2) as the carbon source. Isolate Z-0001 was able to grow with 100% CO as the sole energy source, producing H(2) and CO(2), requiring the presence of 0.2 g l(-1) of acetate as the carbon source. The G+C content of strain Z-0001(T )DNA G+C was 47.8 mol%. Based on 16S rRNA sequence analyses strain Z-0001 fell into the cluster of family Peptococcaceae, within the low G+C content Gram-Positive bacteria, clustering with Thermincola carboxydophila (98% similarity). DNA-DNA hybridization with T. carboxydophila was 27%. On the basis of physiological and phylogenetic data it is proposed that strain Z-0001(T) (=DSMZ 14005, VKM B-2307) should be placed in the genus Thermincola as a new species Thermincola ferriacetica sp. nov.

A novel ecological role of the Firmicutes identified in thermophilic microbial fuel cells

“…Culture-based methods isolated dominant Firmicutes and confirm a previously unidentified electricity-producing role for members of this phylum. Independent anodic electron transfer by Firmicutes is consistent with physiological studies demonstrating that isolated members of this phylum can transfer electrons to solid phase electron acceptors, including iron and manganese, as part of a respiratory metabolism Weber et al, 2006;Zavarzina et al, 2007). Future physiological studies show promise toward unraveling the complexity of interactions in the anode biofilm as well as exploring mechanism of electron transfer to solid phase electron acceptors by Gram-positive bacteria.…”

The use of stable isotope probing to identify key iron-reducing microorganisms involved in anaerobic benzene degradation

“…The closest described representatives are thermophilic Thermincola carboxydiphila (92% sequence identity), (Sokolova et al, 2005) and Thermincola ferriacetica, a facultative anaerobe capable of reducing ferric iron (Zavarzina et al, 2007). Other relatives of the BF1-cluster comprise clones obtained from an in situ reactor treating groundwater contaminated with monochlorobenzene (Alfreider et al, 2002).…”

Carboxydothermus siderophilus sp. nov., a thermophilic, hydrogenogenic, carboxydotrophic, dissimilatory Fe(III)-reducing bacterium from a Kamchatka hot spring

“…An assumption has been made that these two types of chemolithotrophic growth (hydrogenogenic carboxydotrophy and ferric iron reduction) often co-exist in hydrothermal environments . The genera Carboxydothermus, Thermosinus, Thermincola and Thermolithobacter consist of hydrogenogenic carboxydotrophic and Fe(III)-reducing species (Svetlichny et al, 1991;Slobodkin et al, 2006;Sokolova et al, 2004Sokolova et al, , 2005Sokolova et al, , 2007Zavarzina et al, 2007). One of these organisms, Thermosinus carboxydivorans, grows on CO, producing molecular hydrogen, and simultaneously reduces Fe(III) to Fe(II) (Sokolova et al, 2004).…”