| Summary: | Thermal spring microbial mats serve as excellent models to study microbial community ecology as well as a source of novel taxa. Cyanobacteria are integral part of such ecosystems. We sampled thermal springs, spanning from Iceland and Poland to Greece and Tajikistan. Thirteen strains of cyanobacteria were isolated and characterized with taxonomic indices and molecular markers (16S-23S rRNA region and cpcBA gene), and their thermotolerance was evaluated. Screening for the presence of genes encoding three heat shock proteins, non-ribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) was performed. We described two new genera (Hillbrichtia and Amphirytos) with type species (Hillbrichtia pamiria and Amphirytos necridicus) representing Oscillatoriales and Synechococcales orders, respectively. We also found unique lineages inside the genus Thermoleptolyngbya, describing a novel species (T. hindakiae). Isolated strains differed in their thermophilic ability; with the strains best adapted to high temperatures exhibiting presence of all three investigated heat shock proteins’ as well as studied PKS and NRPS genes. Gradual decrease of these genes number complemented the lower tolerance to high temperatures. Additionally, Hillbrichtia pamiria demonstrated production of debromoaplysiatoxin. In this work, we show novel cyanobacteria diversity from thermal springs from disparate environments and possible correlation of thermotolerance and their genetic background.
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