Phenotypic and phylogenetic studies of benthic mat-forming cyanobacteria on the NW Svalbard

Abstract

Cold habitats are diminishing as a result of climate change, while at the same time little is known of the diversity or biogeography of microbes that thrive in such environments. Furthermore, despite the evident importance of cyanobacteria in polar areas, there are hardly any studies focusing on the phylogenetic relationship between the Arctic and Antarctic cyanobacteria. Here, we described cyanobacterial mats as well as epi- and endoliths collected from shallow streams and rocks, respectively, in the northwestern part of Svalbard. Thirteen populations were identified and characterized by employing morphological and molecular (16S rRNA gene sequences) techniques. Our results were compared to analogous information (available from the GenBank) and related to organisms from similar environments located in the Northern and Southern Hemispheres. In general, the morphological and molecular characterizations complemented each other, and the identified Arctic populations belonged to the following orders: Oscillatoriales (6), Nostocales (6), and Chroococcales (1). Twelve of the identified polar populations showed high similarity (94–99% 16S rRNA gene sequence) when compared to other Arctic and Antarctic cyanobacteria. Mat builder Phormidium autumnale shared only 88% similarity with sequences deposited in the GenBank. Our results demonstrate remarkable similarities of microbial life of Svalbard to that in Antarctica and the High Himalayas. Our findings are a starting point for future comparative research of the benthic as well as endolithic populations of cyanobacteria from the Arctic and Antarctica that will yield new insights into the cold and dry limits of life on Earth. They imply global distributions of the low-temperature cyanobacterial populations throughout the cold terrestrial biosphere.