Substantial near-infrared radiation-driven photosynthesis of chlorophyll f -containing cyanobacteria in a natural habitat

Far-red absorbing chlorophylls are constitutively present as chlorophyll (Chl) in the cyanobacterium , or dynamically expressed by synthesis of Chl , red-shifted phycobiliproteins and minor amounts of Chl via far-red light photoacclimation in a range of cyanobacteria, which enables them to use near-infrared-radiation (NIR) for oxygenic photosynthesis. While the biochemistry and molecular physiology of Chl -containing cyanobacteria has been unraveled in culture studies, their ecological significance remains unexplored and no data on their in situ activity exist. With a novel combination of hyperspectral imaging, confocal laser scanning microscopy, and nanoparticle-based O imaging, we demonstrate substantial NIR-driven oxygenic photosynthesis by endolithic, Chl -containing cyanobacteria within natural beachrock biofilms that are widespread on (sub)tropical coastlines. This indicates an important role of NIR-driven oxygenic photosynthesis in primary production of endolithic and other shaded habitats.