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Mehta N, Bradbury H, Benzerara K. Calcium isotope fractionation by intracellular amorphous calcium carbonate (ACC) forming cyanobacteria. GEOBIOLOGY 2024; 22:e12596. [PMID: 38591761 DOI: 10.1111/gbi.12596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/26/2024] [Accepted: 03/27/2024] [Indexed: 04/10/2024]
Abstract
The formation of intracellular amorphous calcium carbonate (ACC) by various cyanobacteria is a widespread biomineralization process, yet its mechanism and importance in past and modern environments remain to be fully comprehended. This study explores whether calcium (Ca) isotope fractionation, linked to ACC-forming cyanobacteria, can serve as a reliable tracer for detecting these microorganisms in modern and ancient settings. Accordingly, we measured stable Ca isotope fractionation during Ca uptake by the intracellular ACC-forming cyanobacterium Cyanothece sp. PCC 7425. Our results show that Cyanothece sp. PCC 7425 cells are enriched in lighter Ca isotopes relative to the solution. This finding is consistent with the kinetic isotope effects observed in the Ca isotope fractionation during biogenic carbonate formation by marine calcifying organisms. The Ca isotope composition of Cyanothece sp. PCC 7425 was accurately modeled using a Rayleigh fractionation model, resulting in a Ca isotope fractionation factor (Δ44Ca) equal to -0.72 ± 0.05‰. Numerical modeling suggests that Ca uptake by these cyanobacteria is primarily unidirectional, with minimal back reaction observed over the duration of the experiment. Finally, we compared our Δ44Ca values with those of other biotic and abiotic carbonates, revealing similarities with organisms that form biogenic calcite. These similarities raise questions about the effectiveness of using the Ca isotope fractionation factor as a univocal tracer of ACC-forming cyanobacteria in the environment. We propose that the use of Δ44Ca in combination with other proposed tracers of ACC-forming cyanobacteria such as Ba and Sr isotope fractionation factors and/or elevated Ba/Ca and Sr/Ca ratios may provide a more reliable approach.
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Affiliation(s)
- Neha Mehta
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique Des Matériaux et de Cosmochimie (IMPMC), Paris, France
- Department of Geosciences, Environment and Society, Université Libre de Bruxelles, Brussels, Belgium
| | - Harold Bradbury
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - Karim Benzerara
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique Des Matériaux et de Cosmochimie (IMPMC), Paris, France
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Garuglieri E, Marasco R, Odobel C, Chandra V, Teillet T, Areias C, Sánchez-Román M, Vahrenkamp V, Daffonchio D. Searching for microbial contribution to micritization of shallow marine sediments. Environ Microbiol 2024; 26:e16573. [PMID: 38217094 DOI: 10.1111/1462-2920.16573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 12/21/2023] [Indexed: 01/15/2024]
Abstract
Micritization is an early diagenetic process that gradually alters primary carbonate sediment grains through cycles of dissolution and reprecipitation of microcrystalline calcite (micrite). Typically observed in modern shallow marine environments, micritic textures have been recognized as a vital component of storage and flow in hydrocarbon reservoirs, attracting scientific and economic interests. Due to their endolithic activity and the ability to promote nucleation and reprecipitation of carbonate crystals, microorganisms have progressively been shown to be key players in micritization, placing this process at the boundary between the geological and biological realms. However, published research is mainly based on geological and geochemical perspectives, overlooking the biological and ecological complexity of microbial communities of micritized sediments. In this paper, we summarize the state-of-the-art and research gaps in micritization from a microbial ecology perspective. Since a growing body of literature successfully applies in vitro and in situ 'fishing' strategies to unveil elusive microorganisms and expand our knowledge of microbial diversity, we encourage their application to the study of micritization. By employing these strategies in micritization research, we advocate promoting an interdisciplinary approach/perspective to identify and understand the overlooked/neglected microbial players and key pathways governing this phenomenon and their ecology/dynamics, reshaping our comprehension of this process.
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Affiliation(s)
- Elisa Garuglieri
- Red Sea Research Center, Division of Biological Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Ramona Marasco
- Red Sea Research Center, Division of Biological Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Charlene Odobel
- Red Sea Research Center, Division of Biological Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Viswasanthi Chandra
- Ali I. Al-Naimi Petroleum Engineering Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Thomas Teillet
- Ali I. Al-Naimi Petroleum Engineering Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Camila Areias
- Department of Earth Sciences, Faculty of Science, Vrije Universiteit, Amsterdam, the Netherlands
| | - Mónica Sánchez-Román
- Department of Earth Sciences, Faculty of Science, Vrije Universiteit, Amsterdam, the Netherlands
| | - Volker Vahrenkamp
- Ali I. Al-Naimi Petroleum Engineering Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Daniele Daffonchio
- Red Sea Research Center, Division of Biological Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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