Phylogeny and taxonomy of Synechococcus-like cyanobacteria

Abstract

Unicellular cyanobacteria constitute a substantial, ecologically important part of freshwater and marine microflora. Solitary, elongated cyanobacterial cells without apparent slime envelopes and dividing in a single plane perpendicular to the longitudinal axis were traditionally classified into the genus Synechococcus. The type species originates from a freshwater benthic habitat while a number of other Synechococcus-like species were described from diverse environments. Morphologically similar, unicellular populations of "Synechococcus" belong to the most abundant oxygen evolving prokaryotes inhabiting freshwater and oceanic picoplanktic communities. Other species from extreme thermal habitats were described from temperatures over 70 °C. Recent molecular analyses, particularly the 16S rRNA gene and other multi-locus gene based phylogenies of Synechococcus-like species reveal the polyphyly and phylogenetic diversity of such simple cyanobacteria emphasizing the necessity of their accurate polyphasic taxonomic re-classification. To better understand the phylogeny of different Synechococcus-like species, we constructed a genome-derived phylogenetic tree using 133 cyanobacterial and eubacterial genomes as well as a 16S rRNA gene phylogenetic tree. Both trees indicate existence of deep splits between individual Synechococcus lineages corresponding with indistinct ecological and cytomorphological differences. The generic units derived from the traditional concept of the genus Synechococcus based on the combined traits and markers must be defined and validly described. The comparative taxonomic classification of phylogenetic clusters corresponding to various morphotypes and genotypes similar to the genus Synechococcus (Cyanobium, Parasynechococcus, Picosynechococcus, Prochlorococcus, Thermosynechococcus, Thermostichus) are discussed in the article.

Coexistence of dominant marine phytoplankton species sustained by nutrient specialization

“…Marine Synechococcus and Prochlorococcus are estimated to have sequentially diverged from a common ancestor during the Devonian, at about 413 million years ago (Mya), and Carboniferous, at around 360 Mya and 341 Mya, respectively 50 . During these periods, a number of genus-level lineages likely evolved within both Synechococcus and Prochlorococcus [51][52][53] , and our data suggest that many others are still waiting to be described (Fig. S6).…”

“…Taxonomic grouping of picocyanobacteria was annotated following recent studies [51][52][53] , individual phylogenetic lineages were subsequently assigned to the traditional ecological scheme of low-light vs.…”

Establishment of a New Filamentous Cyanobacterial Genus, Microcoleusiopsis gen. nov. (Microcoleaceae, Cyanobacteria), from Benthic Mats in Open Channel, Jiangxi Province, China

“…During the field investigation, Oscillatorean cyanobacteria were found to be the main dominant species in the algal mats, and their characterization and correct identification based on the modern taxonomic system should be emphasized. It is expected that the ideal cyanobacteria genera and species in the current cyanobacterial taxonomy should be monophyletic, which means the need to make constant revisions to have this goal achieved [8,14,[35][36][37][38].…”

“…The problem that morphological characteristics could not be well integrated with phylogeny was so evident that it became urgent to revise the existing classification system of cyanobacteria from a more phylogenetic perspective. Thus, based on the polyphasic method, Komárek et al proposed the eight-order system, later the ten-order system, resolving some phylogenetic issues [2,[4][5][6][7][8].…”

Debottlenecking Thermophilic Cyanobacteria Cultivation and Harvesting through the Application of Inner-Light Photobioreactor and Chitosan

“…In recent years we have developed a strain of thermophilic unicellular cyanobacteria of a hot-spring abundant genus Thermosynechococcus [ 25 ] into a promising thermophilic photosynthetic cell factory for CO 2 utilisation [ 5 ]. One of the biggest challenges in using this strain as a cell factory was to develop an efficient cultivation and harvesting method that could be employed in a large scale that allows sufficient amounts of biomass for the production of valuable compounds such as phycocyanins.…”