Porphyrosiphon annulatus sp. nov. (Oscillatoriales, Cyanobacteria) isolated on moist soil in Suwon, Republic of Korea

Abstract

Porphyrosiphon annulatus sp. nov. belonging to Microcoleaceae, Oscillatoriales was collected from the moist soil under the rock in the Gwanggyo Mountain of Suwon City, Gyeonggi Province, Korea and cultured. Using the raw and cultured samples of the collected strains, we observed their morphological features through LM and TEM. Furthermore, their 16S rRNA gene and 16S–23S rRNA intergenic transcribed spacer (ITS) sequences were determined to be used phylogenetic analyses. We affirmed that thick sheath of the cells possessed transversely annular and longitudinal lamellations. The ultrastructure of thylakoids was a radial arrangement, which corresponds with a characteristic of the Microcoleaceae. In addition, P. annulatus displays the most similar morphology with type species P. notarisii; however, it differently holds the transversely annular lamellations with a shorter cell length and relatively dense trichome. Our 16S rRNA gene phylogeny showed that P. annulatus formed a clade with P. notarisii, and their DNA similarity was calculated to be 96.2%. The family Microcoleaceae was found to be paraphyletic with a distinct linage of the genus Porphyrosiphon. The ITS sequence of P. annulatus was unique in length and nucleotide composition, with different secondary structures of D1–D1ʹ and Box-B helices compared to those of close relatives. Overall, morphology and genetic traits of the Korean Porphyrosiphon suggest that P. annulatus should be considered to be a novel species.