Carbon fixation from mineral carbonates.

ABSTRACT: Photoautotrophs assimilate oxidized carbon obtained from one of two sources: dissolved or atmospheric. Despite its size, the pool of lithospheric carbonate is not known to be a direct source for autotrophy. Yet, the mechanism that euendolithic cyanobacteria use to excavate solid carbonates suggests that minerals could directly supply CO₂ for autotrophy. Here, we use stable isotopes and NanoSIMS to show that the cyanobacterium Mastigocoleus testarum derives most of its carbon from the mineral it excavates, growing preferentially as an endolith when lacking dissolved CO₂. Furthermore, natural endolithic communities from intertidal marine carbonate outcrops present carbon isotopic signatures consistent with mineral-sourced autotrophy. These data demonstrate a direct geom

SUBMITTER: Guida BS 

PROVIDER: S-EPMC5715163 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature