Carbon dioxide sequestration into biomineral armor by ants

Over geologic time, Earth’s climate has been shaped by the capture and conversion of atmospheric carbon dioxide (CO2) into stable carbonate minerals, including dolomite [CaMg(CO3)2]. Accelerating natural carbon mineralization offers significant potential for mitigating anthropogenic climate change. Using stable carbon isotope tracking, nano-scale secondary ion mass spectrometry, and 13C solid-state nuclear magnetic resonance spectroscopy, we show that, paralleling global biosphere-level processes, Sericomyrmex amabilis fungus-farming ants rapidly convert CO2 in their nest chambers into a biomineral layer covering their exoskeletons. We further reveal that biogenic carbon mineralization by these ants produces partially ordered dolomite that significantly hardens the exoskeleton, representing a previously unappreciated example of biomineralizing dolomite achieved under ambient conditions that challenge synthetic approaches. This rapid sequestration of CO2 with 60–86 µg per ant (up to 7% body dry weight) into defensive armor provides a fascinating natural system of low-energy-cost mediation of potentially toxic accumulation of atmospheric CO2 that could inform human efforts to mitigate climate change.