Searching for ultraviolet protectors in terrestrial coccoid cyanobacteria from the Atlantic Rain Forest, SP, Brazil

Abstract

Ultraviolet radiation (UV) (<400 nm in wavelength) is very harmful to living organisms, due to the ionizing power that affects DNA and produces reactive oxygen species (ROS). However, many organisms can produce shields to protect themselves against UV, and cyanobacteria are some of them. They have lived on Earth since before the Ozone layer formation, that is, they have had very long time to evolve. Besides, they have been exposed to strong elements that have driven them to develop very efficient physiological adaptations. A proof of this is their capacity to produce two main sunscreens: mycosporine-like amino acids (MAAs) and scytonemin, the former found in different organisms, and the latter exclusively found in cyanobacteria. However, just a few cyanobacterial strains have been studied according to the presence of these protectants, and terrestrial coccoid cyanobacteria show a great potential to produce them: firstly, because coccoid cyanobacteria frequently produce a lot of mucilage, mainly colored, which is an indicative of scytonemin presence and secondly, terrestrial environments, such as bare rocks and soils, can be considered extreme habitats, and the organisms living there must be adapted to hazardous elements of the weather. Thus, our main goal is to investigate the capacity of terrestrial coccoid cyanobacterium strains to produce MAAs and scytonemin. All strains were isolated from the Atlantic Rainforest, Southeastern Brazil. Both investigating methods are spectrometry-based; the first was performed with methanol and the second with acetone. (AU)