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Sub‐lithic photosynthesis in hot desert habitats
Author(s) -
Gwizdala Michal,
Lebre Pedro H.,
MaggsKölling Gillian,
Marais Eugene,
Cowan Don A.,
Krüger Tjaart P. J.
Publication year - 2021
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.15505
Subject(s) - biology , photosynthesis , desiccation , photon flux , microorganism , arid , metagenomics , biofilm , botany , cyanobacteria , habitat , ecology , adaptation (eye) , phototroph , extremophile , bacteria , gene , paleontology , photon , biochemistry , physics , quantum mechanics , neuroscience
Summary In hyper‐arid soil environments, photosynthetic microorganisms are largely restricted to hypolithic (sub‐lithic) habitats: i.e., on the ventral surfaces of translucent pebbles in desert pavements. Here, we combined fluorometric, spectroscopic, biochemical and metagenomic approaches to investigate in situ the light transmission properties of quartz stones in the Namib Desert, and assess the photosynthetic activity of the underlying hypolithic cyanobacterial biofilms. Quartz pebbles greatly reduced the total photon flux to the ventral surface biofilms and filtered out primarily the short wavelength portion of the solar spectrum. Chlorophylls d and f were not detected in biofilm pigment extracts; however, hypolithic cyanobacterial communities showed some evidence of adaptation to sub‐lithic conditions, including the prevalence of genes encoding Helical Carotenoid Proteins, which are associated with desiccation stress. Under water‐saturated conditions, hypolithic communities showed no evidence of light stress, even when the quartz stones were exposed to full midday sunlight. This initial study creates a foundation for future in‐situ and laboratory exploration of various adaptation mechanisms employed by photosynthetic organisms forming hypolithic microbial communities.