Publication Abstracts
Liistro et al. 2026, in press
Liistro, E., B. Boccia, M.N. Parenteau, , and N. La Rocca, 2026: Is constitutive red-shift an advantage for oxygenic photosynthesis under M-dwarf starlight? Insights from Acaryochloris marina sp. str. Moss Beach. FEMS Microbes, in press, doi:10.1093/femsmc/xtag042.
In the next decades, space telescope missions will search for life evidence on exoplanets, focusing on robust biosignatures associated with oxygenic photosynthesis, including atmospheric oxygen accumulation and the Vegetation Red-Edge in surface reflectance spectra. Many habitable rocky exoplanets orbit M dwarf stars, whose spectral energy distribution may condition the rise and evolution of oxygenic photosynthesis. M dwarf stars emit predominantly far-red (700-750 nm) and near-infrared (750-1000 nm) light, and relatively little visible (400-700 nm) radiation, which on Earth predominantly drives photochemistry in most oxygenic phototrophs. Previous experiments proved some oxygenic phototrophs can photosynthesize under simulated M dwarf light but less efficiently than under solar radiation simulated in the range 365-780 nm. Indeed, tested organisms present photosynthetic apparatus evolved to harvest Sun's visible light, however, M dwarfs' irradiation might select adaptations optimized for harvesting far-red / near-infrared light. We measured sensitivities of a far-red/near-infrared-utilizing cyanobacterium, Acaryochloris marina sp. str. Moss Beach to simulated M dwarf spectrum and primeval anoxic, CO2-rich atmosphere. This strain constitutively presents a high content of chlorophyll d, with in vivo absorption peak at 710 nm. Its permanently red-shifted photosynthetic apparats required no acclimation to the stellar spectrum, maintaining strong growth and oxygen production, higher than that registered under simulated solar light.
Moreover, abundant chlorophyll d caused a shift in whole-cell reflectance: the red-edge was beyond 700 nm, resulting in a Chl d-near-infrared-edge. Overall, a potentially similar metabolism on exoplanets orbiting M dwarfs could successfully produce both a gaseous biosignature and a characteristic surface biosignature.
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BibTeX Citation
@unpublished{li00610e,
author={Liistro, E. and Boccia, B. and Parenteau, M. N. and Kiang, N. Y. and La Rocca, N.},
title={Is constitutive red-shift an advantage for oxygenic photosynthesis under M-dwarf starlight? Insights from Acaryochloris marina sp. str. Moss Beach},
year={2026},
journal={FEMS Microbes},
doi={10.1093/femsmc/xtag042},
note={Manuscript accepted for publication}
}
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RIS Citation
TY - INPR ID - li00610e AU - Liistro, E. AU - Boccia, B. AU - Parenteau, M. N. AU - Kiang, N. Y. AU - La Rocca, N. PY - 2026 TI - Is constitutive red-shift an advantage for oxygenic photosynthesis under M-dwarf starlight? Insights from Acaryochloris marina sp. str. Moss Beach JA - FEMS Microbes DO - 10.1093/femsmc/xtag042 ER -
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