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Meyer NR, Morono Y, Dekas AE. Single-cell analysis reveals an active and heterotrophic microbiome in the Guaymas Basin deep subsurface with significant inorganic carbon fixation by heterotrophs. Appl Environ Microbiol 2024; 90:e0044624. [PMID: 38709099 PMCID: PMC11334695 DOI: 10.1128/aem.00446-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 04/04/2024] [Indexed: 05/07/2024] Open
Abstract
The marine subsurface is a long-term sink of atmospheric carbon dioxide with significant implications for climate on geologic timescales. Subsurface microbial cells can either enhance or reduce carbon sequestration in the subsurface, depending on their metabolic lifestyle. However, the activity of subsurface microbes is rarely measured. Here, we used nanoscale secondary ion mass spectrometry (nanoSIMS) to quantify anabolic activity in 3,203 individual cells from the thermally altered deep subsurface in the Guaymas Basin, Mexico (3-75 m below the seafloor, 0-14°C). We observed that a large majority of cells were active (83%-100%), although the rates of biomass generation were low, suggesting cellular maintenance rather than doubling. Mean single-cell activity decreased with increasing sediment depth and temperature and was most strongly correlated with porewater sulfate concentrations. Intracommunity heterogeneity in microbial activity decreased with increasing sediment depth and age. Using a dual-isotope labeling approach, we determined that all active cells analyzed were heterotrophic, deriving the majority of their cellular carbon from organic sources. However, we also detected inorganic carbon assimilation in these heterotrophic cells, likely via processes such as anaplerosis, and determined that inorganic carbon contributes at least 5% of the total biomass carbon in heterotrophs in this community. Our results demonstrate that the deep marine biosphere at Guaymas Basin is largely active and contributes to subsurface carbon cycling primarily by not only assimilating organic carbon but also fixing inorganic carbon. Heterotrophic assimilation of inorganic carbon may be a small yet significant and widespread underappreciated source of labile carbon in the global subsurface. IMPORTANCE The global subsurface is the largest reservoir of microbial life on the planet yet remains poorly characterized. The activity of life in this realm has implications for long-term elemental cycling, particularly of carbon, as well as how life survives in extreme environments. Here, we recovered cells from the deep subsurface of the Guaymas Basin and investigated the level and distribution of microbial activity, the physicochemical drivers of activity, and the relative significance of organic versus inorganic carbon to subsurface biomass. Using a sensitive single-cell assay, we found that the majority of cells are active, that activity is likely driven by the availability of energy, and that although heterotrophy is the dominant metabolism, both organic and inorganic carbon are used to generate biomass. Using a new approach, we quantified inorganic carbon assimilation by heterotrophs and highlighted the importance of this often-overlooked mode of carbon assimilation in the subsurface and beyond.
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Affiliation(s)
- Nicolette R. Meyer
- Department of Earth System Science, Stanford University, Stanford, California, USA
| | - Yuki Morono
- Kochi Institute for Core Sample Research, Institute for Extra-cutting-edge Science and Technology Avantgarde Research (X-STAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Nankoku, Kochi, Japan
| | - Anne E. Dekas
- Department of Earth System Science, Stanford University, Stanford, California, USA
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Burr DJ, Drauschke J, Kanevche K, Kümmel S, Stryhanyuk H, Heberle J, Perfumo A, Elsaesser A. Stable Isotope Probing-nanoFTIR for Quantitation of Cellular Metabolism and Observation of Growth-Dependent Spectral Features. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2400289. [PMID: 38708804 DOI: 10.1002/smll.202400289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 04/16/2024] [Indexed: 05/07/2024]
Abstract
This study utilizes nanoscale Fourier transform infrared spectroscopy (nanoFTIR) to perform stable isotope probing (SIP) on individual bacteria cells cultured in the presence of 13C-labelled glucose. SIP-nanoFTIR simultaneously quantifies single-cell metabolism through infrared spectroscopy and acquires cellular morphological information via atomic force microscopy. The redshift of the amide I peak corresponds to the isotopic enrichment of newly synthesized proteins. These observations of single-cell translational activity are comparable to those of conventional methods, examining bulk cell numbers. Observing cells cultured under conditions of limited carbon, SIP- nanoFTIR is used to identify environmentally-induced changes in metabolic heterogeneity and cellular morphology. Individuals outcompeting their neighboring cells will likely play a disproportionately large role in shaping population dynamics during adverse conditions or environmental fluctuations. Additionally, SIP-nanoFTIR enables the spectroscopic differentiation of specific cellular growth phases. During cellular replication, subcellular isotope distribution becomes more homogenous, which is reflected in the spectroscopic features dependent on the extent of 13C-13C mode coupling or to specific isotopic symmetries within protein secondary structures. As SIP-nanoFTIR captures single-cell metabolism, environmentally-induced cellular processes, and subcellular isotope localization, this technique offers widespread applications across a variety of disciplines including microbial ecology, biophysics, biopharmaceuticals, medicinal science, and cancer research.
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Affiliation(s)
- David J Burr
- Department of Physics, Experimental Biophysics and Space Sciences, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Janina Drauschke
- Department of Physics, Experimental Biophysics and Space Sciences, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Katerina Kanevche
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Steffen Kümmel
- Department of Technical Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Hryhoriy Stryhanyuk
- Department of Technical Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Joachim Heberle
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Amedea Perfumo
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Polar Terrestrial Environmental Systems, Telegrafenberg, 14473, Potsdam, Germany
| | - Andreas Elsaesser
- Department of Physics, Experimental Biophysics and Space Sciences, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
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Arandia-Gorostidi N, Parada AE, Dekas AE. Single-cell view of deep-sea microbial activity and intracommunity heterogeneity. THE ISME JOURNAL 2023; 17:59-69. [PMID: 36202927 PMCID: PMC9750969 DOI: 10.1038/s41396-022-01324-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 09/08/2022] [Accepted: 09/12/2022] [Indexed: 12/15/2022]
Abstract
Microbial activity in the deep sea is cumulatively important for global elemental cycling yet is difficult to quantify and characterize due to low cell density and slow growth. Here, we investigated microbial activity off the California coast, 50-4000 m water depth, using sensitive single-cell measurements of stable-isotope uptake and nucleic acid sequencing. We observed the highest yet reported proportion of active cells in the bathypelagic (up to 78%) and calculated that deep-sea cells (200-4000 m) are responsible for up to 34% of total microbial biomass synthesis in the water column. More cells assimilated nitrogen derived from amino acids than ammonium, and at higher rates. Nitrogen was assimilated preferentially to carbon from amino acids in surface waters, while the reverse was true at depth. We introduce and apply the Gini coefficient, an established equality metric in economics, to quantify intracommunity heterogeneity in microbial anabolic activity. We found that heterogeneity increased with water depth, suggesting a minority of cells contribute disproportionately to total activity in the deep sea. This observation was supported by higher RNA/DNA ratios for low abundance taxa at depth. Intracommunity activity heterogeneity is a fundamental and rarely measured ecosystem parameter and may have implications for community function and resilience.
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Affiliation(s)
| | - A E Parada
- Department of Earth System Science, Stanford University, Stanford, CA, USA
| | - A E Dekas
- Department of Earth System Science, Stanford University, Stanford, CA, USA.
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Cyle KT, Klein AR, Aristilde L, Martínez CE. Dynamic utilization of low-molecular-weight organic substrates across a microbial growth rate gradient. J Appl Microbiol 2022; 133:1479-1495. [PMID: 35665577 DOI: 10.1111/jam.15652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/05/2022] [Accepted: 05/31/2022] [Indexed: 11/28/2022]
Abstract
AIM Low-molecular-weight organic substances (LMWOSs) are at the nexus between microorganisms, plant roots, detritus, and the soil mineral matrix. Nominal oxidation state of carbon (NOSC) has been suggested a potential parameter for modeling microbial uptake rates of LMWOSs and the efficiency of carbon incorporation into new biomass. METHODS AND RESULTS In this study, we assessed the role of compound class and oxidation state on uptake kinetics and substrate-specific carbon use efficiency (SUE) during the growth of three model soil microorganisms, a fungal isolate (Penicillium spinulosum) and two bacterial isolates (Paraburkholderia solitsugae, and Ralstonia pickettii). Isolates were chosen that spanned a growth rate gradient (0.046-0.316 h-1 ) in media containing 34 common LMWOSs at realistically low initial concentrations (25 μM each). Clustered, co-utilization of LMWOSs occurred for all three organisms. Potential trends (p < 0.05) for early utilization of more oxidized substrates were present for the two bacterial isolates (P. solitsugae and R. pickettii), but high variability (R2 < 0.15) and a small effect of NOSC indicate these relationships are not useful for prediction. The SUEs of selected substrates ranged from 0.16-0.99 and there was no observed relationship between NOSC and SUE. CONCLUSION Our results do not provide compelling population-level support for NOSC as a predictive tool for either uptake kinetics or the efficiency of use of LMWOS in soil solution. SIGNIFICANCE AND IMPACT OF THE STUDY Metabolic strategies of organisms are likely more important than chemical identity in determining LMWOS cycling in soils. Previous community-level observations may be biased towards fast-responding bacterial community members.
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Affiliation(s)
- K Taylor Cyle
- Soil and Crop Sciences, School of Integrative Plant Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Annaleise R Klein
- Department of Biological and Environmental Engineering, Cornell University, Riley-Robb Hall, Ithaca, NY 14853.,Australian Synchrotron, Australian Nuclear Science and Technology Organisation, Clayton, VIC 3168, Australia
| | - Ludmilla Aristilde
- Department of Biological and Environmental Engineering, Cornell University, Riley-Robb Hall, Ithaca, NY 14853.,Department of Civil and Environmental Engineering, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL, 60208, USA
| | - Carmen Enid Martínez
- Soil and Crop Sciences, School of Integrative Plant Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, 14853, USA
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