Steffen Buessecker

All Publications

• Biosignature Molecules Accumulate and Persist in Evaporitic Brines: Implications for Planetary Exploration. Astrobiology Pozarycki, C., Seaton, K. M., C Vincent, E., Novak Sanders, C., Nuñez, N., Castillo, M., Ingall, E., Klempay, B., Pontefract, A., Fisher, L. A., Paris, E. R., Buessecker, S., Alansson, N. B., Carr, C. E., Doran, P. T., Bowman, J. S., Schmidt, B. E., Stockton, A. M. 2024; 24 (8): 795-812

  Abstract

  The abundance of potentially habitable hypersaline environments in our solar system compels us to understand the impacts of high-salt matrices and brine dynamics on biosignature detection efforts. We identified and quantified organic compounds in brines from South Bay Salt Works (SBSW), where evapoconcentration of ocean water enables exploration of the impact of NaCl- and MgCl2-dominated brines on the detection of potential biosignature molecules. In SBSW, organic biosignature abundance and distribution are likely influenced by evapoconcentration, osmolyte accumulation, and preservation effects. Bioluminescence assays show that adenosine triphosphate (ATP) concentrations are higher in NaCl-rich, low water activity (aw) samples (<0.85) from SBSW. This is consistent with the accumulation and preservation of ATP at low aw as described in past laboratory studies. The water-soluble small organic molecule inventory was determined by using microchip capillary electrophoresis paired with high-resolution mass spectrometry (µCE-HRMS). We analyzed the relative distribution of proteinogenic amino acids with a recently developed quantitative method using CE-separation and laser-induced fluorescence (LIF) detection of amino acids in hypersaline brines. Salinity trends for dissolved free amino acids were consistent with amino acid residue abundance determined from the proteome of the microbial community predicted from metagenomic data. This highlights a tangible connection up and down the "-omics" ladder across changing geochemical conditions. The detection of water-soluble organic compounds, specifically proteinogenic amino acids at high abundance (>7 mM) in concentrated brines, demonstrates that potential organic biomarkers accumulate at hypersaline sites and suggests the possibility of long-term preservation. The detection of such molecules in high abundance when using diverse analytical tools appropriate for spacecraft suggests that life detection within hypersaline environments, such as evaporates on Mars and the surface or subsurface brines of ocean world Europa, is plausible and argues such environments should be a high priority for future exploration. Key Words: Salts-Analytical chemistry-Amino acids-Biosignatures-Capillary electrophoresis-Preservation. Astrobiology 24, 795-812.

  View details for DOI 10.1089/ast.2023.0122

  View details for PubMedID 39159437

• Mcr-dependent methanogenesis in Archaeoglobaceae enriched from a terrestrial hot spring. The ISME journal Buessecker, S., Chadwick, G. L., Quan, M. E., Hedlund, B. P., Dodsworth, J. A., Dekas, A. E. 2023

  Abstract

  The preeminent source of biological methane on Earth is methyl coenzyme M reductase (Mcr)-dependent archaeal methanogenesis. A growing body of evidence suggests a diversity of archaea possess Mcr, although experimental validation of hypothesized methane metabolisms has been missing. Here, we provide evidence of a functional Mcr-based methanogenesis pathway in a novel member of the family Archaeoglobaceae, designated Methanoglobus nevadensis, which we enriched from a terrestrial hot spring on the polysaccharide xyloglucan. Our incubation assays demonstrate methane production that is highly sensitive to the Mcr inhibitor bromoethanesulfonate, stimulated by xyloglucan and xyloglucan-derived sugars, concomitant with the consumption of molecular hydrogen, and causing a deuterium fractionation in methane characteristic of hydrogenotrophic and methylotrophic methanogens. Combined with the recovery and analysis of a high-quality M. nevadensis metagenome-assembled genome encoding a divergent Mcr and diverse potential electron and carbon transfer pathways, our observations suggest methanogenesis in M. nevadensis occurs via Mcr and is fueled by the consumption of cross-fed byproducts of xyloglucan fermentation mediated by other community members. Phylogenetic analysis shows close affiliation of the M. nevadensis Mcr with those from Korarchaeota, Nezhaarchaeota, Verstraetearchaeota, and other Archaeoglobales that are divergent from well-characterized Mcr. We propose these archaea likely also use functional Mcr complexes to generate methane on the basis of our experimental validation in M. nevadensis. Thus, divergent Mcr-encoding archaea may be underestimated sources of biological methane in terrestrial and marine hydrothermal environments.

  View details for DOI 10.1038/s41396-023-01472-3

  View details for PubMedID 37452096

  View details for PubMedCentralID 5543129

• Mineral-catalysed formation of marine NO and N2O on the anoxic early Earth NATURE GEOSCIENCE Buessecker, S., Imanaka, H., Ely, T., Hu, R., Romaniello, S. J., Cadillo-Quiroz, H. 2022; 15 (12): 1056-+

  View details for DOI 10.1038/s41561-022-01089-9

  View details for Web of Science ID 000928399600009

• Coupled abiotic-biotic cycling of nitrous oxide in tropical peatlands. Nature ecology & evolution Buessecker, S., Sarno, A. F., Reynolds, M. C., Chavan, R., Park, J., Fontanez Ortiz, M., Perez-Castillo, A. G., Panduro Pisco, G., Urquiza-Munoz, J. D., Reis, L. P., Ferreira-Ferreira, J., Furtunato Maia, J. M., Holbert, K. E., Penton, C. R., Hall, S. J., Gandhi, H., Boechat, I. G., Gucker, B., Ostrom, N. E., Cadillo-Quiroz, H. 2022

  Abstract

  Atmospheric nitrous oxide (N2O) is a potent greenhouse gas thought to be mainly derived from microbial metabolism as part of the denitrification pathway. Here we report that in unexplored peat soils of Central and South America, N2O production can be driven by abiotic reactions (≤98%) highly competitive to their enzymatic counterparts. Extracted soil iron positively correlated with in situ abiotic N2O production determined by isotopic tracers. Moreover, we found that microbial N2O reduction accompanied abiotic production, essentially closing a coupled abiotic-biotic N2O cycle. Anaerobic N2O consumption occurred ubiquitously (pH 6.4-3.7), with proportions of diverse clade II N2O reducers increasing with consumption rates. Our findings show that denitrification in tropical peat soils is not a purely biological process but rather a 'mosaic' of abiotic and biotic reduction reactions. We predict that hydrological and temperature fluctuations differentially affect abiotic and biotic drivers and further contribute to the high N2O flux variation in the region.

  View details for DOI 10.1038/s41559-022-01892-y

  View details for PubMedID 36202923

• An essential role for tungsten in the ecology and evolution of a previously uncultivated lineage of anaerobic, thermophilic Archaea. Nature communications Buessecker, S., Palmer, M., Lai, D., Dimapilis, J., Mayali, X., Mosier, D., Jiao, J., Colman, D. R., Keller, L. M., St John, E., Miranda, M., Gonzalez, C., Gonzalez, L., Sam, C., Villa, C., Zhuo, M., Bodman, N., Robles, F., Boyd, E. S., Cox, A. D., St Clair, B., Hua, Z., Li, W., Reysenbach, A., Stott, M. B., Weber, P. K., Pett-Ridge, J., Dekas, A. E., Hedlund, B. P., Dodsworth, J. A. 2022; 13 (1): 3773

  Abstract

  Trace metals have been an important ingredient for life throughout Earth's history. Here, we describe the genome-guided cultivation of a member of the elusive archaeal lineage Caldarchaeales (syn. Aigarchaeota), Wolframiiraptor gerlachensis, and its growth dependence on tungsten. A metagenome-assembled genome (MAG) of W. gerlachensis encodes putative tungsten membrane transport systems, as well as pathways for anaerobic oxidation of sugars probably mediated by tungsten-dependent ferredoxin oxidoreductases that are expressed during growth. Catalyzed reporter deposition-fluorescence in-situ hybridization (CARD-FISH) and nanoscale secondary ion mass spectrometry (nanoSIMS) show that W. gerlachensis preferentially assimilates xylose. Phylogenetic analyses of 78 high-quality Wolframiiraptoraceae MAGs from terrestrial and marine hydrothermal systems suggest that tungsten-associated enzymes were present in the last common ancestor of extant Wolframiiraptoraceae. Our observations imply a crucial role for tungsten-dependent metabolism in the origin and evolution of this lineage, and hint at a relic metabolic dependence on this trace metal in early anaerobic thermophiles.

  View details for DOI 10.1038/s41467-022-31452-8

  View details for PubMedID 35773279