Identification of far-red light acclimation in an endolithic Chroococcidiopsis strain and associated genomic features: Implications for oxygenic photosynthesis on exoplanets

Daniela Billi; Alessandro Napoli; Claudia Mosca; Claudia Fagliarone; Roberto de Carolis; Amedeo Balbi; Matteo Scanu; Vera M Selinger; Laura A Antonaru; Dennis J Nürnberg

doi:10.3389/fmicb.2022.933404

Identification of far-red light acclimation in an endolithic Chroococcidiopsis strain and associated genomic features: Implications for oxygenic photosynthesis on exoplanets

Front Microbiol. 2022 Aug 4:13:933404. doi: 10.3389/fmicb.2022.933404. eCollection 2022.

Authors

Affiliations

¹ Department of Biology, University of Rome Tor Vergata, Rome, Italy.
² Ph.D. Program in Cellular and Molecular Biology, Department of Biology, University of Rome Tor Vergata, Rome, Italy.
³ Department of Physics, University of Rome Tor Vergata, Rome, Italy.
⁴ Department of Physics, Biochemistry and Biophysics of Photosynthetic Organisms, Freie Universität Berlin, Berlin, Germany.

Abstract

Deserts represent extreme habitats where photosynthetic life is restricted to the lithic niche. The ability of rock-inhabiting cyanobacteria to modify their photosynthetic apparatus and harvest far-red light (near-infrared) was investigated in 10 strains of the genus Chroococcidiopsis, previously isolated from diverse endolithic and hypolithic desert communities. The analysis of their growth capacity, photosynthetic pigments, and apcE2-gene presence revealed that only Chroococcidiopsis sp. CCMEE 010 was capable of far-red light photoacclimation (FaRLiP). A total of 15 FaRLiP genes were identified, encoding paralogous subunits of photosystem I, photosystem II, and the phycobilisome, along with three regulatory elements. CCMEE 010 is unique among known FaRLiP strains by undergoing this acclimation process with a significantly reduced cluster, which lacks major photosystem I paralogs psaA and psaB. The identification of an endolithic, extremotolerant cyanobacterium capable of FaRLiP not only contributes to our appreciation of this phenotype's distribution in nature but also has implications for the possibility of oxygenic photosynthesis on exoplanets.

Keywords: Chroococcidiopsis; FaRLiP; astrobiology; biosignature; desert cyanobacteria.