Based on daily rates of carbon uptake, the team estimates that these microbialites can absorb the equivalent of nine to 16 kilograms of carbon dioxide every year per square meter. That’s like a tennis court-sized area absorbing as much CO2 every year as three acres of forest, making these systems one of the most efficient biological mechanisms for long-term carbon storage observed in nature.
2. Nature Communication (08 December 2025) (https://www.nature.com/articles/s41467-025-66552-8) (https://doi.org/10.1038/s41467-025-66552-8)
Integration of multiple metabolic pathways supports high rates of carbon precipitation in living microbialites
Authors: Rachel E. Sipler, Eric W. Isemonger, Samantha C. Waterworth, Steffen H. Büttner, Thomas G. Bornman, Ross-Lynne A. Gibb, Xavier Siwe Noundou, Siddarthan Venkatachalam & Rosemary A. Dorrington
Abstract: Microbialites are lithifying microbial mats that form multi-layered structures via biological carbon (C) uptake and carbonate precipitation. Here we relate C uptake and precipitation rates to taxonomic diversity and functional capacity of bacterial communities in supratidal freshwater microbialites. Diel assays and analysis of functional gene capacity reveal that photosynthesis is bolstered by light-independent, biological C uptake mechanisms, including biomineralization and chemoautotrophy. Through integration of these mechanisms, microbialites can capture inorganic C over a 24-hour cycle at a rate of 7-12 g C m-2 24 h-1. Notably, up to 87 % of the C taken up is precipitated as inorganic carbon, capturing 2.4 − 4.3 kg C m-2 year-1. Based on observed porosity and laboratory-based accretion rates, this equates to 13-23 mm of vertical calcium carbonate accumulation per year. Hence, contemporary microbialites provide a highly effective biological mechanism to precipitate dissolved CO2 as geologically stable carbonate mineral deposits.
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