Bacterial communities were detected in deep crystalline rock aquifers within the Columbia River Basalt Group (CRB). CRB ground waters contained up to 60 μM dissolved H 2 and autotrophic microorganisms outnumbered heterotrophs. Stable carbon isotope measurements implied that autotrophic methanogenesis dominated this ecosystem and was coupled to the depletion of dissolved inorganic carbon. In laboratory experiments, H 2 , a potential energy source for bacteria, was produced by reactions between crushed basalt and anaerobic water. Microcosms containing only crushed basalt and ground water supported microbial growth. These results suggest that the CRB contains a lithoautotrophic microbial ecosystem that is independent of photosynthetic primary production.

Many global environmental agendas, including halting biodiversity loss, reversing land degradation, and limiting climate change, depend upon retaining forests with high ecological integrity, yet the scale and degree of forest modification remain poorly quantified and mapped. By integrating data on observed and inferred human pressures and an index of lost connectivity, we generate a globally consistent, continuous index of forest condition as determined by the degree of anthropogenic modification. Globally, only 17.4 million km2 of forest (40.5%) has high landscape-level integrity (mostly found in Canada, Russia, the Amazon, Central Africa, and New Guinea) and only 27% of this area is found in nationally designated protected areas. Of the forest inside protected areas, only 56% has high landscape-level integrity. Ambitious policies that prioritize the retention of forest integrity, especially in the most intact areas, are now urgently needed alongside current efforts aimed at halting deforestation and restoring the integrity of forests globally.

Bacillus infernus sp. nov. was isolated from ca. 2,700 m below the land surface in the Taylorsville Triassic Basin in Virginia. B. infernus was a strict anaerobe that grew on formate or lactate with Fe(III), MnO,, trimethylamine oxide, or nitrate (reduced to nitrite) as an electron acceptor, and it also grew fermentatively on glucose. Type strain TH-23 and five reference strains were gram-positive rods that were thermophilic (growth occurred at 61"C), halotolerant (good growth occurred in the presence of Na+ concentrations up to 0.6 M), and very slightly alkaliphilic (good growth occurred at pH 7.3 to 7.8). A phylogenetic analysis of its 16s rRNA indicated that B. infernus should be classified as a new species of the genus Bacilius. B. infernus is the only strictly anaerobic species in the genus Bacillus.

Abiotic production of H 2 from basalt reactions in aqueous solutions is hypothesized to support microbial ecosystems in deep subsurface aquifers, such as those found in the Columbia River Basalt group (CRB). We investigated factors controlling this phenomenon, including rock composition, pH, temperature, sterilization method, reducing agents, and product removal. Ferrous silicate minerals were found to be the basalt components responsible for H 2 production from anaerobic water-rock interactions. H 2 evolution was faster at pH < 7 but occurred from pH 5 to pH 11, which covers the pH range (7-10) measured in CRB groundwaters. The onset of H 2 evolution coincided with the appearance of dissolved Fe 2+ , and an apparent alkaline inhibition could be alleviated by the addition of excess FeCl 2 . This may reflect, in part, the low redox conditions needed for H 2 evolution and suggests that H 2 may be controlled by reaction rates of ferrous silicate minerals. Rates were higher at 60°C than at 30°C, suggesting that the geothermal gradient may lead to increased H 2 production at depth. The results were consistent with the hypothesis that basalt-redox reactions support primary production by microorganisms in some terrestrial subsurface environments.

The microbial diversity in two deep, confined aquifers, the Grande Ronde (1270 m) and the Priest Rapids (316 m), Hanford Reservation, Washington, USA, was investigated by sampling from artesian wells. These basaltic aquifers were alkaline (pH 8.5 to 10.5) and anaerobic (Eh -200 to -450 mV). The wells were allowed to free-flow until pH and Eh stabilized, then the microflora was sampled with water filtration and flow-through sandtrap methods. Direct microscopic counts showed 7.6 × 10(5) and 3.6 × 10(3) bacteria ml(-1) in water from the Grande Ronde and Priest Rapids aquifers, respectively. The sand filter method yielded 5.7 × 10(8) and 1.1 × 10(5) cells g(-1) wet weight of sand. The numbers of bacteria did not decrease as increasing volumes of water were flushed out. The heterotrophic diversity of these bacterial populations was assessed using enrichments for 20 functional groups. These groups were defined by their ability to grow in a matrix of five different electron acceptors (O2, Fe(III), NO3 (-), SO4 (2-), HCO3 (-)) and four groups of electron donors (fermentation products, monomers, polymers, aromatics) in a mineral salts medium at pH 9.5. Growth was assessed by protein production. Culture media were subsequently analyzed to determine substrate utilization patterns. Substrate utilization patterns proved to be more reliable indicators of the presence of a particular physiological group than was protein production. The sand-trap method obtained a greater diversity of bacteria than did water filtration, presumably by enriching the proportion of normally sessile bacteria relative to planktonic bacteria. Substrate utilization patterns were different for microflora from the two aquifers and corresponded to their different geochemistries. Activities in the filtered water enrichments more closely matched those predicted by aquifer geochemistry than did the sand-trap enrichments. The greatest activities were found in Fe(III)-reducing enrichments from both wells, SO4-reducing enrichments from the Grande Ronde aquifer, and methanogenic enrichments from the Priest Rapids aquifer. Organisms from these aquifers may be useful for high-pH bioremediation applications as well as production of biotechnological products. These organisms may also be useful for modeling potential reactions near buried concrete, as might be found in subsurface waste depositories.