Extremophile cyanobacteria from thermo-mineral springs in Galicia (NW Spain)

Abstract

Cyanobacteria are photosynthetic prokaryotic organisms found in very diverse aquatic and terrestrial habitats. In aquatic environments, they develop in marine and fresh water where we can find them from ice to hot springs. To survive in such varied and sometimes extreme environments, they have a wide range of secondary metabolites to compete successfully in the different habitats of the planet. This has an enormous importance from a biotechnological and industrial point of view. We were studied the species composition of cyanobacteria assemblages in six thermo-mineral springs in Galicia (NW Spain). Four are considered hot and two cold, and some contain hydrogen sulphide. A total of 21 taxa have been recorded. Of the species identified, the most diverse genus is Leptolyngbya with four species, followed by Chroococcus with three species and Aphanocapsa, Phormidium and Lyngbya with two species. The most abundant species was Jaaginema angustissimum, followed by Leptolyngbya laminosa and Symploca thermalis. One of the most important parameters for cyanobacteria species diversity in hot springs is temperature. In the two cold springs, 7 different species were found, and only Aphanocapsa conferta was common to both springs. Cyanobacterial species were more numerous in the four hot springs, with 15 different species and only Calothrix thermalis common to these hot springs. It is difficult to establish a characteristic cyanobacterial flora for the thermal waters of the Galician springs since there are significant differences in the communities from the six sites studied.