Characterization of cyanobacteria isolated from thermal muds of Balaruc-Les-Bains (France) and description of a new genus and species Pseudochroococcuscouteii

Cyanobacteria are able to synthesize a high diversity of natural compounds that account for their success in the colonization of a variety of ecological niches. Many of them have beneficial properties. The mud from the thermal baths of Balaruc-Les-Bains, one of the oldest thermal baths in France, has long been recognized as a healing treatment for arthro-rheumatic diseases. To characterize the cyanobacteria living in these muds and the metabolites they potentially produce, several strains were isolated from the water column and biofilms of the retention basin and analyzed using a polyphasic approach. Morphological, ultrastructural and molecular (16S rRNA gene and 16S-23S ITS region sequencing) methods were employed to identify nine cyanobacterial strains belonging to the orders Chroococcales, Synechococcales, Oscillatoriales and Nostocales. The combination of morphological and genetic characteristics supported the description of a new genus and species with the type species as Pseudo-chroococcus couteii. The high taxonomic diversity in the muds of the thermal baths of Balaruc-Les-Bains along with literature reports of the potential for bioactive metabolite synthesis of these taxa allowed us to hypothesize that some of the metabolites produced by these strains could contribute to the therapeutic properties of the muds from Thermes de Balaruc-Les-Bains.