Siderite-based anaerobic iron cycle driven by autotrophic thermophilic microbial consortium.

Using a sample from a terrestrial hot spring (pH 6.8, 60 °C), we enriched a thermophilic microbial consortium performing anaerobic autotrophic oxidation of hydrothermal siderite (FeCO), with CO/bicarbonate as the electron acceptor and the only carbon source, producing green rust and acetate. In order to reproduce Proterozoic environmental conditions during the deposition of banded iron formation (BIF), we incubated the microbial consortium in a bioreactor that contained an unmixed anoxic layer of siderite, perfectly mixed N/CO-saturated liquid medium and microoxic (2% O) headspace.

Symbiotic cooperation between freshwater rock-boring bivalves and microorganisms promotes silicate bioerosion.

Bioerosion is a process with a high socio-economic impact that contributes to coastal retreat, and likely to increase with climate change. Whereas limestone bioerosion is well explained by a combination of mechanical and chemical pathways, the bioerosion mechanisms of silicates, which are harder and chemically more resistant, remain elusive. Here we investigated the interface between siltstone and freshwater rock-boring bivalves Lignopholas fluminalis (Bivalvia: Pholadidae).

Syntrophic growth of alkaliphilic anaerobes controlled by ferric and ferrous minerals transformation coupled to acetogenesis.

Redox-active iron minerals can act as energy sources or electron-transferring mediators in microbial syntrophic associations, being important means of interspecies metabolic cooperation in sedimentary environments. Alkaline conditions alter the thermodynamic stability of iron minerals, influencing their availability for interspecies syntrophic interactions. We have modeled anaerobic alkaliphilic microbial associations in ethanol-oxidizing co-culture of an obligate syntroph Candidatus "Contubernalis alkalaceticum" and a facultative lithotroph Geoalkalibacter ferrihydriticus, which is capable of dissimilatory Fe(III) reduction and homoacetogenic oxidation of Fe(II) with CO.

Cryovolcanism on the Earth: Origin of a Spectacular Crater in the Yamal Peninsula (Russia).

Geological activity on icy planets and planetoids includes cryovolcanism. Until recently, most research on terrestrial permafrost has been engineering-oriented, and many related phenomena have received too little attention. Although fast processes in the Earth's cryosphere were known before, they have never been attributed to cryovolcanism.

Discovery of a silicate rock-boring organism and macrobioerosion in fresh water.

Macrobioerosion is a common process in marine ecosystems. Many types of rock-boring organisms break down hard substrates, particularly carbonate rocks and calcareous structures such as dead corals and shells. In paleontology, the presence of rocks with boreholes and fossil macroboring assemblage members is one of the primary diagnostic features of shallow marine paleo-environments.