Cave Pools in Carlsbad Caverns National Park Contain Diverse Bacteriophage Communities and Novel Viral Sequences.

Viruses are the most abundant biological entities on Earth, and they play a critical role in the environment and biosphere where they regulate microbial populations and contribute to nutrient cycling. Environmental viruses have been the most studied in the ocean, but viral investigations have now spread to other environments. Here, viral communities were characterized in four cave pools in Carlsbad Caverns National Park to test the hypotheses that (i) viral abundance is ten-fold higher than prokaryotic cell abundance in cavern pools, (ii) cavern pools contain novel viral sequences, and (iii) viral communities in pools from developed portions of the cave are distinct from those of pools in undeveloped parts of the same cave.

Radiolytic support for oxidative metabolism in an ancient subsurface brine system.

Long-isolated subsurface brine environments (Ma-Ga residence times) may be habitable if they sustainably provide substrates, e.g. through water-rock reactions, that support microbial catabolic energy yields exceeding maintenance costs.

To form or not to form a reaction complex: exploring ion-molecule reactions between CH isomers and Xe and O.

Ion-molecule reactions are an essential contributor to the chemistry of a diverse range of environments. While a great deal of work has been done to understand the fundamental mechanisms driving these reactions, there is still much more to discover. Here, we expand upon prior studies on ion-molecule reactions involving two isomers of CH, allene (HCH) and propyne (HCH).

Radiolytically reworked Archean organic matter in a habitable deep ancient high-temperature brine.

Investigations of abiotic and biotic contributions to dissolved organic carbon (DOC) are required to constrain microbial habitability in continental subsurface fluids. Here we investigate a large (101-283 mg C/L) DOC pool in an ancient (>1Ga), high temperature (45-55 °C), low biomass (10-10 cells/mL), and deep (3.2 km) brine from an uranium-enriched South African gold mine.

Kr excess and other noble gases identify a billion-year-old radiogenically-enriched groundwater system.

Deep within the Precambrian basement rocks of the Earth, groundwaters can sustain subsurface microbial communities, and are targets of investigation both for geologic storage of carbon and/or nuclear waste, and for new reservoirs of rapidly depleting resources of helium. Noble gas-derived residence times have revealed deep hydrological settings where groundwaters are preserved on millions to billion-year timescales. Here we report groundwaters enriched in the highest concentrations of radiogenic products yet discovered in fluids, with an associated Kr excess in the free fluid, and residence times >1 billion years.