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Silverman SN, Wijker RS, Sessions AL. Biosynthetic and catabolic pathways control amino acid δ 2H values in aerobic heterotrophs. Front Microbiol 2024; 15:1338486. [PMID: 38646628 PMCID: PMC11026604 DOI: 10.3389/fmicb.2024.1338486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 02/20/2024] [Indexed: 04/23/2024] Open
Abstract
The hydrogen isotope ratios (δ2HAA values) of amino acids in all organisms are substantially fractionated relative to growth water. In addition, they exhibit large variations within microbial biomass, animals, and human tissues, hinting at rich biochemical information encoded in such signals. In lipids, such δ2H variations are thought to primarily reflect NADPH metabolism. Analogous biochemical controls for amino acids remain largely unknown, but must be elucidated to inform the interpretation of these measurements. Here, we measured the δ2H values of amino acids from five aerobic, heterotrophic microbes grown on different carbon substrates, as well as five Escherichia coli mutant organisms with perturbed NADPH metabolisms. We observed similar δ2HAA patterns across all organisms and growth conditions, which-consistent with previous hypotheses-suggests a first-order control by biosynthetic pathways. Moreover, δ2HAA values varied systematically with the catabolic pathways activated for substrate degradation, with variations explainable by the isotopic compositions of important cellular metabolites, including pyruvate and NADPH, during growth on each substrate. As such, amino acid δ2H values may be useful for interrogating organismal physiology and metabolism in the environment, provided we can further elucidate the mechanisms underpinning these signals.
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Affiliation(s)
- Shaelyn N. Silverman
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States
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Muñoz-Marín MDC, López-Lozano A, Moreno-Cabezuelo JÁ, Díez J, García-Fernández JM. Mixotrophy in cyanobacteria. Curr Opin Microbiol 2024; 78:102432. [PMID: 38325247 DOI: 10.1016/j.mib.2024.102432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 12/22/2023] [Accepted: 01/10/2024] [Indexed: 02/09/2024]
Abstract
Cyanobacteria evolved the oxygenic photosynthesis to generate organic matter from CO2 and sunlight, and they were responsible for the production of oxygen in the Earth's atmosphere. This made them a model for photosynthetic organisms, since they are easier to study than higher plants. Early studies suggested that only a minority among cyanobacteria might assimilate organic compounds, being considered mostly autotrophic for decades. However, compelling evidence from marine and freshwater cyanobacteria, including toxic strains, in the laboratory and in the field, has been obtained in the last decades: by using physiological and omics approaches, mixotrophy has been found to be a more widespread feature than initially believed. Furthermore, dominant clades of marine cyanobacteria can take up organic compounds, and mixotrophy is critical for their survival in deep waters with very low light. Hence, mixotrophy seems to be an essential trait in the metabolism of most cyanobacteria, which can be exploited for biotechnological purposes.
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Affiliation(s)
- María Del Carmen Muñoz-Marín
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Universitario ceiA3, Universidad de Córdoba, Edificio Severo Ochoa, planta 1, ala Este, Campus de Rabanales, 14071 Córdoba, Spain
| | - Antonio López-Lozano
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Universitario ceiA3, Universidad de Córdoba, Edificio Severo Ochoa, planta 1, ala Este, Campus de Rabanales, 14071 Córdoba, Spain
| | - José Ángel Moreno-Cabezuelo
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Universitario ceiA3, Universidad de Córdoba, Edificio Severo Ochoa, planta 1, ala Este, Campus de Rabanales, 14071 Córdoba, Spain
| | - Jesús Díez
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Universitario ceiA3, Universidad de Córdoba, Edificio Severo Ochoa, planta 1, ala Este, Campus de Rabanales, 14071 Córdoba, Spain.
| | - José Manuel García-Fernández
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Universitario ceiA3, Universidad de Córdoba, Edificio Severo Ochoa, planta 1, ala Este, Campus de Rabanales, 14071 Córdoba, Spain.
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Millette NC, Gast RJ, Luo JY, Moeller HV, Stamieszkin K, Andersen KH, Brownlee EF, Cohen NR, Duhamel S, Dutkiewicz S, Glibert PM, Johnson MD, Leles SG, Maloney AE, Mcmanus GB, Poulton N, Princiotta SD, Sanders RW, Wilken S. Mixoplankton and mixotrophy: future research priorities. JOURNAL OF PLANKTON RESEARCH 2023; 45:576-596. [PMID: 37483910 PMCID: PMC10361813 DOI: 10.1093/plankt/fbad020] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 04/14/2023] [Indexed: 07/25/2023]
Abstract
Phago-mixotrophy, the combination of photoautotrophy and phagotrophy in mixoplankton, organisms that can combine both trophic strategies, have gained increasing attention over the past decade. It is now recognized that a substantial number of protistan plankton species engage in phago-mixotrophy to obtain nutrients for growth and reproduction under a range of environmental conditions. Unfortunately, our current understanding of mixoplankton in aquatic systems significantly lags behind our understanding of zooplankton and phytoplankton, limiting our ability to fully comprehend the role of mixoplankton (and phago-mixotrophy) in the plankton food web and biogeochemical cycling. Here, we put forward five research directions that we believe will lead to major advancement in the field: (i) evolution: understanding mixotrophy in the context of the evolutionary transition from phagotrophy to photoautotrophy; (ii) traits and trade-offs: identifying the key traits and trade-offs constraining mixotrophic metabolisms; (iii) biogeography: large-scale patterns of mixoplankton distribution; (iv) biogeochemistry and trophic transfer: understanding mixoplankton as conduits of nutrients and energy; and (v) in situ methods: improving the identification of in situ mixoplankton and their phago-mixotrophic activity.
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Affiliation(s)
| | - Rebecca J Gast
- Woods Hole Oceanographic Institution, 266 Woods Hole Rd, Woods Hole, MA 02543, USA
| | - Jessica Y Luo
- NOAA Geophysical Fluid Dynamics Laboratory, 201 Forrestal Rd., Princeton, NJ 08540, USA
| | - Holly V Moeller
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, 1120 Noble Hall, Santa Barbara, CA 93106, USA
| | - Karen Stamieszkin
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - Ken H Andersen
- Center for Ocean Life, Natl. Inst. of Aquatic Resources, Technical University of Denmark, Kemitorvet, Bygning 202, Kongens Lyngby 2840, Denmark
| | - Emily F Brownlee
- Department of Biology, St. Mary’s College of Maryland, 18952 E. Fisher Road, St. Mary’s City, MD 20686, USA
| | - Natalie R Cohen
- Skidaway Institute of Oceanography, University of Georgia, 10 Ocean Science Circle, Savannah, GA 31411, USA
| | - Solange Duhamel
- Department of Molecular and Cellular Biology, The University of Arizona, 1007 E Lowell Street, Tucson, AZ 85721, USA
| | - Stephanie Dutkiewicz
- Center for Global Change Science, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02874, USA
| | - Patricia M Glibert
- Horn Point Laboratory, University of Maryland Center for Environmental Science, 2020 Horns Point Rd, Cambridge, MD 21613, USA
| | - Matthew D Johnson
- Woods Hole Oceanographic Institution, 266 Woods Hole Rd, Woods Hole, MA 02543, USA
| | - Suzana G Leles
- Department of Marine and Environmental Biology, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089, USA
| | - Ashley E Maloney
- Geosciences Department, Princeton University, Guyot Hall, Princeton, NJ 08544, USA
| | - George B Mcmanus
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Rd., Groton, CT 06340, USA
| | - Nicole Poulton
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - Sarah D Princiotta
- Biology Department, Pennsylvania State University, Schuylkill Campus, 200 University Drive, Schuylkill Haven, PA 17972, USA
| | - Robert W Sanders
- Department of Biology, Temple University, 1900 N. 12th St., Philadelphia, PA 19122, USA
| | - Susanne Wilken
- Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, Amsterdam, 1098 XH, The Netherlands
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Cross AT, van der Ent A, Wickmann M, Skates LM, Sumail S, Gebauer G, Robinson A. Capture of mammal excreta by Nepenthes is an effective heterotrophic nutrition strategy. ANNALS OF BOTANY 2022; 130:927-938. [PMID: 36306274 PMCID: PMC9851329 DOI: 10.1093/aob/mcac134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/27/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND AND AIMS While isotopic enrichment of nitrogen (15N) and carbon (13C) is often used to determine whether carnivorous plant species capture and assimilate nutrients from supplemental sources such as invertebrate prey or mammal excreta (heterotrophic nutrition), little is known about how successful the different strategies deployed by carnivorous plants are at obtaining supplemental nutrition. The collection of mammalian faeces by Nepenthes (tropical pitcher plants) is the result of a highly specialized biological mutualism that results in heterotrophic nitrogen gain; however, it remains unknown how effective this strategy is in comparison to Nepenthes species not known to collect mammalian faeces. METHODS We examined how isotopic enrichment varied in the diverse genus Nepenthes, among species producing pitchers for invertebrate capture and species exhibiting mutualisms for the collection of mammal excreta. Enrichment factors were calculated from δ15N and δ13C values from eight Nepenthes species and naturally occurring hybrids along with co-occurring reference (non-carnivorous) plants from three mountain massifs in Borneo: Mount Kinabalu, Mount Tambuyukon and Mount Trus Madi. RESULTS All Nepenthes examined, except N. edwardsiana, were significantly enriched in 15N compared to co-occurring non-carnivorous plants, and 15N enrichment was more than two-fold higher in species with adaptations for the collection of mammal excreta compared with other Nepenthes. CONCLUSIONS The collection of mammal faeces clearly represents a highly effective strategy for heterotrophic nitrogen gain in Nepenthes. Species with adaptations for capturing mammal excreta occur exclusively at high elevation (i.e. are typically summit-occurring) where previous studies suggest invertebrate prey are less abundant and less frequently captured. As such, we propose this strategy may maximize nutritional return by specializing towards ensuring the collection and retention of few but higher-value N sources in environments where invertebrate prey may be scarce.
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Affiliation(s)
- Adam T Cross
- School of Molecular and Life Sciences, Curtin University, Kent Street, Bentley, WA 6102, Australia
- Ecological Health Network, 1330 Beacon St., Suite 355a, Brookline, MA 02446, USA
| | - Antony van der Ent
- Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, QLD 4072, Australia
| | - Miriam Wickmann
- Laboratory of Isotope Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Germany
| | - Laura M Skates
- School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
- Kings Park Science, Department of Biodiversity Conservation and Attractions, 2 Kattidj Close, Kings Park, WA 6005, Australia
| | - Sukaibin Sumail
- Herbarium, Sabah Parks, PO Box 10626, Kota Kinabalu, Sabah 88806, Malaysia
| | - Gerhard Gebauer
- Laboratory of Isotope Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Germany
| | - Alastair Robinson
- National Herbarium of Victoria, Royal Botanic Gardens Victoria, Melbourne, VIC 3004, Australia
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