A new species ofScytonemaisolated from Bilaspur, Chhattisgarh, India

Abstract

Filamentous cyanobacterium (strain 10C-PS) isolated from a fresh water body of Bilaspur, Chhattisgarh, India is being described as new species of the polyphyletic genus Scytonema. Phenotypic, molecular and phylogenetic characterization was performed and the combined results validated the strain as a new species. Careful observations of the filaments, presence of a distinctly textured sheath throughout the length of the trichome, differences in the shape and dimensions of the vegetative cells, and heterocytes provided reliable morphological signals that the strain differed from rest of the closely related species. Sequencing of the 16S rRNA gene showed 96.89% sequence similarity with Scytonema hofmanni PCC 7110 while rbcl and psbA sequencing showed 95% and 92% similarities with Scytonema hofmanni PCC 7110 and Nostoc sp. PCC 7524 respectively while the nifD gene sequence similarity was found to be 96% with Scytonema hofmanni PCC 7110. The PC-IGS region was sequenced and concatenated cpcB, IGS and cpcA regions indicated 97% closest similarity with Scytonema sp. PCC 7110 and Scytonema bohnerii Ind24. Subsequent phylogenetic analyses gave a strong pattern of distinct clustering in case of all the molecular markers. The phenotypic, genetic and phylogenetic observations prove conclusively that the strain 10C-PS is a new species in the genus Scytonema with the name proposed being Scytonema bilaspurensis.Key words: 16S rRNA, cpcB, cyanobacterium, IGS and cpcA, phylogeny, psbA gene, rbcl gene, Scytonema bilaspurensis.A long evolutionary history, morphological intricacies and culturing problems have made cyanobacterial taxonomy, an exhaustive but interesting field of study. Advent of quality sequence data and phylogenetic approaches have helped in providing a better resolution of cyanobacterial phylogeny and evolution. Substantial taxonomic assignments of the recent years (Anagnostidis & Kom arek, 1985, 1988, 1990Kom arek & Anagnostidis, 1986, 1989B€ udel & Kauff, 2012) have helped in developing a better understanding of cyanobacterial systematics. The recent, S€ ußwasserflora series on the cyanoprokaryotes (cyanobacteria) has been shaped up to accommodate both morphological and genotypic data in congruence along with supporting more revisionary work in terms of discovering new genera and species (Kom arek, 2013). Kom arek et al. (2014) have placed the genus Scytonema in the family Scytonemataceae of the order Nostocales. As per the recent S€ ußwasserflora series it is well established that this group is indeed a species-rich group of isopolar, falsebranching heterocytous cyanobacteria. This group has also been revised through a polyphasic approach and hence, taxonomic changes can be expected. Initial investigations of some of the workers (Fiore et al., 2007;Aguiar et al., 2008;Sant'anna et al., 2011;Vaccarino & Johansen, 2011; Becerra-Absal on et al., 2013; Kom arek, 2013) have shown that at least the genera Scytonema and Brasilonema form a monophyletic clade, based on a 16S rRNA data analysis. Some of the definin...

Polyphasic evaluation and cytotoxic investigation of isolated cyanobacteria with an emphasis on potent activities of a Scytonema strain

“…Thus, based on the most closet 16S rRNA gene sequence similarity and phylogenetic relatedness to Scytonema bilaspurense 10C-PS, strain NK13 was provisionally identified as Scytonema bilaspurense . In addition, the appearance of strain NK13 was in congruence with the description of Scytonema bilaspurense (Singh et al, 2016 ) by double/single false branching, shape, and dimension of vegetative cells/heterocysts. Therefore, based on polyphasic evaluations (morphology, molecular characterization, and freshwater habitat), strain NK13 was classified as Scytonema bilaspurense .…”

“…Strain NK13 shared the highest 16S rRNA sequence similarity of 99.76 % with strain Scytonema bilaspurense 10C-PS ( Table 2 ), and both strains clustered with the typical Scytonema strains, including Scytonema hofmanni PCC7110 and Scytonema pachmarhiense 10A1-PS (Komárek et al, 2013 ; Singh et al, 2016 ; Saraf et al, 2018 ), by a relatively high SH-aLRT/BS/BPP values of 97.9/99/1 ( Figure 2 , cluster E). The phylogenetic tree based on rbcL gene sequences further supported the placement of strain NK13 in the genus Scytonema ( Figure 3 ), in which it shared 100% and 99.63% rbcL gene sequence similarity with Scytonema sp.…”