Benthic cyanobacteria of the genus Nodularia are non-toxic, without gas vacuoles, able to glide and genetically more diverse than planktonic Nodularia

Abstract

Diversity and ecological features of cyanobacteria of the genus Nodularia from benthic, periphytic and soil habitats are less well known than those of Nodularia from planktonic habitats. Novel benthic Nodularia strains were isolated from the Baltic Sea and their morphology, the presence of gas vacuoles, nodularin production, gliding, 16S rRNA gene sequences, rpoB, rbcLX and ndaF genes, and gvpA-IGS regions were examined, as well as short tandemly repeated repetitive sequence fingerprints. Strains were identified as Nodularia spumigena, Nodularia sphaerocarpa or Nodularia harveyana on the basis of the size and shape of the different types of cells and the presence or absence of gas vacuoles. The planktonic strains of N. spumigena mostly had gas vacuoles and produced nodularin, whereas the benthic strains of N. sphaerocarpa and N. harveyana lacked gas vacuoles and did not produce nodularin (except for strain PCC 7804). The benthic strains were also able to glide on surfaces. In the genetic analyses, the planktonic N. spumigena and benthic N. sphaerocarpa formed monophyletic clusters, but the clusters were very closely related. Benthic strains determined as N. harveyana formed the most diverse and distant group of strains. In addition to phylogenetic analyses, the lack of the gvpA-IGS region and ndaF in N. sphaerocarpa and N. harveyana distinguished these species from the planktonic N. spumigena. Therefore, ndaF can be considered as a potential diagnostic tool for detecting and quantifying Baltic Sea bloom-forming, nodularin-producing N. spumigena strains. The data confirm that only one morphologically and genetically distinct planktonic species of Nodularia, N. spumigena, and at least two benthic species, N. sphaerocarpa and N. harveyana, exist in the Baltic Sea.

Taxonomy of cyanobacteria: a contribution to consensus approach

“…There are several examples showing the clear necessity of applying polyphasic approach in taxonomy of cyanobacteria (Castenholz, 1992;Palinska et al, 1996;Otsuka et al, 2000;Lyra et al, 2005;Rajaniemi et al, 2005). Palinska et al (1996) indicated in their studies on Synechococcus/Synechocystis/ Merismopedia/Eucapsis complex that the great morphological diversity observed in nature and (partially) in culture does not necessarily reflect genetic diversity.…”

“…chromatic adaptations, salinity tolerance, vitamin requirements) were proved to be variable with changing environmental and culture conditions (Rippka et al, 1979;Dor & Hornhoff, 1985;Holtkamp, 1985;Castenholz & Waterbury, 1989;Palinska et al, 1996;Otsuka et al, 2000;Lyra et al, 2005;Rajaniemi et al, 2005).…”

Phylogenetic evaluation of cyanobacteria preserved as historic herbarium exsiccata

“…the Baltic Sea (Mazur & Pliń ski, 2003), whereas other forms of Nodularia are benthic and non-toxic (Lyra et al, 2005). Nodularia spumigena var.…”

“…Furthermore, similarity between the 16S rRNA gene sequence of the herbarium Nodularia and Nodularia spumigena strain PCC 73104, the non-toxic type strain for Nodularia spumigena, was 99?7 %. According to Lyra et al (2001Lyra et al ( , 2005 and Moffitt et al (2001), Nodularia spumigena is a planktonic, toxin-producing organism with extremely high 16S rRNA gene sequence similarity values ranging from 98?5-100 %. Both non-toxic strains (PCC 73104 and UTEX B 2092) were isolated from the same ecological niche (alkaline soil) and shared less gene sequence similarity (99?7 %) with the herbarium Nodularia spumigena than with other planktonic Nodularia.…”

Phylogenetic analysis of heterocystous cyanobacteria (Subsections IV and V) using highly iterated palindromes as molecular markers

“…The genus Cylindrospermum whose four strains were under study, again vehemently supported the intermixing clustering pattern of heterocystous cyanobacteria with all the four strains showing shifting phylogenetic affiliations in all the trees and the PCA analyses along with, showing proximity with even false branched and true branched heterocystous cyanobacteria . The strain Calothrix whose three strains were incorporated in the study showed once again very true resemblance with the affinities that were obtained in the structural and the functional gene phylogenetic schemes with all the strains showing phylogenetic affinities of shifting patterns (Rasmussen and Svenning 1998;Lyra et al 2005;Singh et al 2013). PCA analysis placed the Calothrix strains at different levels and clusters with its affinities being evident with unbranched, false branched, and even true branched strains.…”