December 8, 2025Open Access

Integration of multiple metabolic pathways supports high rates of carbon precipitation in living microbialites

RSRachel E. Sipler EIEric W. Isemonger SWSamantha C. Waterworth

Key Points

Integration of metabolic pathways enhances carbon precipitation in microbialites, leading to significant rates of inorganic carbon capture.
Bacterial communities exhibit diverse functional capacities, with up to 87% of carbon taken up being precipitated as calcium carbonate.
Diel assays show that microbialites capture carbon at rates of 7-12 g C m−2 24 h−1, emphasizing their efficiency in carbon uptake.
Microbialites serve as effective biological mechanisms for precipitating dissolved CO2 into stable carbonate mineral deposits.

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.

اسأل الذكاء الاصطناعي

Bookmark

View Full Paper