(2011a). ecosystem through geochemical, biomarker profiling, and molecular ecology studies. The chemistry of ABT-888 (Veliparib) the benthic water was similar to the rest of the water column, except for variable amounts of ammonium (up to 2.8 ppm) ABT-888 (Veliparib) and nitrate (up to 0.13 ppm). A existence detector chip having a 300-antibody microarray exposed the presence of biomass in the form of exopolysaccharides and additional microbial markers connected to several phylogenetic organizations and potential microaerobic and anaerobic metabolisms such as nitrate reduction. DNA analyses showed that 27% of the Archaea sequences corresponded to a group of ammonia-oxidizing archaea (AOA) related (97%) to spp. and spp. (Thaumarchaeota), and 4% of Bacteria sequences to nitrite-oxidizing bacteria from your genus, suggesting a coupling between ammonia and nitrite oxidation. Mesocosm experiments with the specific AOA inhibitor 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) shown an AOA-associated ammonia oxidation activity with the simultaneous build up of nitrate and sulfate. The results showed a rich benthic microbial community dominated by microaerobic and anaerobic metabolisms flourishing under aphotic, low temp (4C), and relatively high pressure, that might be a suitable terrestrial analog of additional planetary settings. case and underwater flashlights, together with an aluminium lander for cams and lamps, and; (iv) an Ekman grab (May) for sample collection sediments down to approximately 10 cm. ABT-888 (Veliparib) A 1.8 L sample (S1) was collected around the 5th of April 2015, at 264 m depth, at coordinates S 333839.6, W 700742.9. One month later (5th of May) a 2.0 L (including water and sediments) of a second sample (S2) was collected 541 m far from the first one and from 269 m depth, at coordinates S 333842.9, W 700722.26. Each sample was distributed into 3C4 500 mL bottles, and immediately kept in a cooler, stored refrigerated, and one bottle shipped to Madrid (Spain) for analysis. Samples were stored in a chilly room (4C) until utilized for LDChip and DNA extraction (2 months later) and Mesocosms experiment (9 months later). Temperature at the lake bed was 4C and was measured with a YSI 6600 multi-parameter probe onboard the lake lander platform. Geochemical Analysis In previous work we reported the geochemistry of the Laguna Negra waters down to 20 m depth from samples collected and filtered on site (Echeverra-Vega et al., 2018). In the present work, the samples were stored at 4C and geochemical analysis was carried out 2 months after sampling. To determine the anion content (inorganic ones such as Cl-, Br-, NO3-, NO2-, PO42-, SO42-, and small organic ones such as acetate, formate, propionate, tartrate, oxalate) in the water IFNG around the samples, 2 g of wet sediment were centrifuged at 2000 for 10 min to separate the interstitial water (IW) from your coarse solid material. Then, the supernatant was directly analyzed by ion chromatography using a Metrohm 861 Advanced Compact Ion Chromatographer IC (Metrohm AG, Herisau, Switzerland), set up to detect all the anions indicated above in a single run, as explained in Parro et al. (2011a). The ion chromatograph was calibrated for measuring, in a single run, the presence of several inorganic and organic anions. For each anion, 6 different concentration within the range shown below were used to make the calibration curves: Fluoride (2C0.08 ppm), Chloride (10C0.4 ppm), Nitrite (5C0.2 ppm), Bromide (2C0.08 ppm), Nitrate (50C2 ppm), Sulfate (200C8 ppm), Acetate (5C0.2 ppm), Propionate (2C0.08 ppm), Formate (2C0.08 ppm), Phosphate (2C0.08 ppm), Tartrate (2C0.08 ppm), and Oxalate (2C0.08 ppm). Under these conditions the limit of detection is in the range of 0.005C0.010 ppm in the run sample. Ammonium concentration was determined with a colorimetric method with the Reflectoquant? 20C180 mg L-1 Ammonium Test kit (Merk) following the providers instructions. Antibody Microarrays: Printing LDChip and Fluorescent Sandwich Immunoassay The Life Detector Chip (LDChip) is an antibody microarray-based biosensor specifically developed for planetary exploration and environmental monitoring (Rivas et al., 2008; Parro et al., 2011a). The LDChip used in this work contained over 300 antibodies including antibodies reported previously (Parro et al., 2011a, 2018) and new ones (Supplementary Table S1). The new set of rabbit polyclonal antibodies were produced, as previously reported (Rivas et al., 2008), against exopolysaccharide (EPS) material and whole cellular lysates from several strains of psychrophilic microorganisms (Supplementary Table S1) isolated from High Canadian Arctic (Prof. Lyle Whyte, McGill University or college collection) and perchlorate reducing bacteria (from Prof. John Coates, Berkeley University or college). The strains belong to.