Sub-lithic photosynthesis in hot desert habitats.
Michal GwizdalaPedro H LebreGillian Maggs-KöllingEugene MaraisDon A CowanTjaart P J KrügerPublished in: Environmental microbiology (2021)
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.
Keyphrases
- candida albicans
- spinal cord
- biofilm formation
- deep brain stimulation
- pseudomonas aeruginosa
- staphylococcus aureus
- risk factors
- molecular docking
- stress induced
- prefrontal cortex
- genome wide
- urinary tract
- magnetic resonance
- spinal cord injury
- magnetic resonance imaging
- cystic fibrosis
- escherichia coli
- computed tomography
- multidrug resistant
- gram negative
- genome wide identification
- single molecule