The unexpected megadiverse world of soil cyanobacteria

Abstract

This chapter will summarize current knowledge on soil cyanobacteria, an often neglected group of microorganisms that are almost ubiquitous on Earth, as cyanobacteria have been found in the most extreme environments, from arid deserts or hypersaline environments to tropical rainforests. However, their diversity and distribution are still poorly known due to the lack of cyanobacteria sampling on some habitats, though with current molecular techniques such as DNA barcoding from environmental samples, our capability to identify them in multiple environments has increased greatly. Firstly, a short review of the current status of cyanobacterial taxonomy, including the differences between botanical and microbiological classifications, the vast number of new genera and families, and novel groups derived mainly from genomic sequencing as the two groups of non-photosynthetic Cyanobacteria. Then morpho-functional adaptations will be discussed, namely the morphological diversity and derived functionality of photosynthetic cyanobacteria, including pigmentation, specialized cells, and multi-cellular lifestyles as filaments or colonies and the functional capabilities of soil cyanobacteria, including non-photosynthetic strategies. Then, in ecology of soil cyanobacteria, the environmental preferences of soil cyanobacteria will be described in the form of the type of habitats where soil cyanobacteria have been found and their edapho-climatic characteristics with a special dedication to biocrusts, a topsoil community where soil cyanobacteria are present and can play essential ecological roles. Then, a review on global distribution of soil cyanobacteria, including information from sampling campaigns around the world and research where their distribution is inferred through modeling. Finally, the chapter will end with a review of the current knowledge of the effects of climate change on these soil microorganisms, coming from multiple experimental works on this matter, and the future prospects on the effects of climate change on their diversity and distribution.