Summary Extracellular electron transport (EET) is a microbial process that allows microorganisms to transport electrons to and from insoluble substrates outside of the cell. Although progress has been made in understanding how microbes transfer electrons to insoluble substrates, the process of receiving electrons has largely remained unexplored. We investigated redox potentials favourable for donating electrons to dissolved an...

Summary Serpentinization is a geologic process that produces highly reduced, hydrogen‐rich fluids that support microbial communities under high pH conditions. We investigated the activity of microbes capable of extracellular electron transfer in a terrestrial serpentinizing system known as ‘The Cedars’. Measuring current generation with an on‐site two‐electrode system, we observed daily oscillations in current with the current...

Summary Yellowstone Lake is central to the balanced functioning of the Yellowstone ecosystem, yet little is known about the microbial component of its food chain. A remotely operated vehicle provided video documentation ( http://www.tbi.montana.edu/media/videos/ ) and allowed sampling of dilute surface zone waters and enriched lake floor hydrothermal vent fluids. Vent emissions contained substantial H 2 S, CH 4 , CO 2 and H 2...

Culture‐dependent and independent methods were used to evaluate the microbial communities in cores collected at depths up to 200 m in oil‐bearing and oil‐free strata near the Sagara oil reservoir near Shizuoka, Japan. Direct microbial counts revealed much higher numbers (2.2 × 10 4 −7.9 × 10 6 /g) of microbes in the oil‐bearing strata than in the oil‐free zones, where counts were uniform at approximately 1.0 × 10 4 /g. Molecul...

Summary Within a phylum Crenarchaeota , only some members of the hyperthermophilic class Thermoprotei , have been cultivated and characterized. In this study, we have constructed a metagenomic library from a microbial mat formation in a subsurface hot water stream of the Hishikari gold mine, Japan, and sequenced genome fragments of two different phylogroups of uncultivated thermophilic Crenarchaeota : (i) hot water crenarchaeo...

Summary We report the isolation and properties of several species of bacteria from Siberian permafrost. Half of the isolates were spore‐forming bacteria unable to grow or metabolize at subzero temperatures. Other Gram‐positive isolates metabolized, but never exhibited any growth at − 10°C. One Gram‐negative isolate metabolized and grew at − 10°C, with a measured doubling time of 39 days. Metabolic studies of several isolates s...

Biology is believed to play a large role in the cycling of iron and manganese in many freshwater environments, but specific microbial groups indigenous to these systems have not been well characterized. To investigate the populations of Bacteria and Archaea associated with metal‐rich sediments from Green Bay, WI, we extracted nucleic acids and analysed the phylogenetic relationships of cloned 16S rRNA genes. Because nucleic ac...