In the current review, we focus on UV-tolerant cyanobacteria which in desert environments, are principally composed of Scytonema and Nostoc species. These cyanobacteria live on the soil surface and possess direct adaptive mechanisms to the desert environment, particularly to temperature fluctuations and wet/dry cycles.
They have developed the ability to reversibly activate their metabolism, limiting photosynthesis and growth to wet periods when the cells are rehydrated. During hot, dry periods, the cells
enter into a quiescent state. Although photosystems I and II (PSI, PSII) are damaged during high light and dryness, in vitro studies have shown that PS I and PSII are self-repaired and operational within minutes of the cell’s rehydration