Proposal of Purpurea gen. nov. (Nostocales, Cyanobacteria), a novel cyanobacterial genus from wet soil samples in Tibet, China

Abstract

A new cyanobacterial strain CHAB5880 morphologically identified to the Nostoc-like genus was isolated from wet soil samples in Tibet of China, and it was taxonomically and phylogenetically characterized based on the polyphasic approach combining morphological, genetic and ecological characteristics. Colonies of this strain were usually purple to black, irregularly clustering, forming diffluent mucilage. The phylogenetic tree based on 16S rRNA gene indicated that the novel strain formed a unique cluster, and separated from the 'Nostoc sensu stricto' clade and from the clades of the morphologically similar genera Aliinostoc, Desmonostoc and Holatia. The secondary structure of ITS between 16S-23S rRNA gene in the strain CHAB5880 showed unique patterns of D1-D1', Box-B and V3 helix, which distinguished it from other heterocytous genera. Purpurea tibecum sp. nov. was designated as the type species of the genus.