Strains Of Unicellular Cyanobacteria Research Articles

A new cyanobacterial genus Altericista and three species, A. lacusladogae sp. nov., A. violacea sp. nov., and A. variichlora sp. nov., described using a polyphasic approach.

Several strains of unicellular cyanobacteria from the culture collection of St. Petersburg State University, St. Petersburg, Russia (CALU), which were preliminary identified as Synechocystis sp., are reclassified in the new genus Altericista. Three new species are proposed, A. lacusladogae, A. violacea, and A. variichlora. The last species produces accessory chlorophylls d and f in cultures illuminated by far-red light, an attribute rarely observed in cyanobacteria, especially in unicellular strains. This genus is morphologically similar to Synechocysis having coccoid cells that divide in two successive planes at right angles, containing no sheath or capsule, and having the lamellar system represented by peripheral concentric thylakoids. Altericista shows ecological, biochemical, and physiological characters unlike those in Synechocystis and has the distinguishing phenotypic characters as follows: freshwater, non-halotolerant ecotype; palmitate and α-linoleate as major fatty acids; and the ability to photoacclimate, including several types of complementary chromatic adaptation. Genetic differences from Synechocystis sp. include 16S rRNA, rpoC1, and rbcL gene sequences, as well as sequence and folding of 16S-23S ITS.

The functioning of the CO2 concentrating mechanism in several cyanobacterial strains: a review of general physiological characteristics, genes, proteins, and recent advances

Cyanobacteria (blue-green algae) possess an environmental adaptation for survival at low CO2 concentrations. The adaptation is known as a CO2 concentrating mechanism (CCM), and it functions to actively transport and accumulate inorganic carbon ( and CO2; Ci) within the cell and then uses this Ci pool to provide elevated CO2 concentrations around the primary CO2-fixing enzyme, ribulose bisphosphate carboxylase-oxygenase (Rubisco). It appears that the site of CO2 elevation is within a unique microcompartment known as the carboxysome, which is a proteinaceous polyhedral body that contains most, if not all, of the Rubisco within the cell. This review covers comparative aspects of physiology, genetics, and proteins involved in the cyanobacterial CCM with particular focus on recent advances. This review highlights information on three strains of unicellular cyanobacteria, namely Synechocystis PCC6803 (freshwater strain; for which a full genome database is now available), Synechococcus PCC7002 (coastal marine strain) and Synechococcus PCC7942 (freshwater strain). Genes that may be involved in the CCM, directly or indirectly, are summarized in tabular form. For Synechocystis PCC6803, the number of genes related to CCM activity is now in excess of 50; however, 19 of these components have the potential to code for several distinct type-1, NADH dehydrogenase complexes.Key words: cyanobacteria, CO2 concentrating mechanism, carboxysomes, genes, photosynthesis, transporters.

Two unicellular cyanobacteria which reproduce by budding

Two strains of unicellular cyanobacteria which reproduce exclusively by budding are described and assigned to genus Chamaesiphon.

Lactate dehydrogenases in cyanobacteria

NAD-linked lactate dehydrogenases specific for the D- and L-lactate have been demonstrated in a number of strains of unicellular cyanobacteria. The D-lactate dehydrogenase of one strain (Synechococcus 6716) was partially purified and its properties were studied. The enzyme has a molecular weight of ca. 115000-120000, is highly specific, autooxidizable, and susceptible to inhibition by iodoacetamide, oxamate and ATP. The possible physiological functions of the enzyme in the metabolism of the organism were investigated. D-lactate carbon was incorporated in cell material during photosynthetic growth with CO2, but lactate was not used as sole source for carbon for photosynthetic or chemosynthetic development. D-lactate and pyruvate were oxidized aerobically in the dark by resting cell suspensions with the assimilation mainly of the C2 and the C3 carbon atoms. In the oxidation of lactate, acetate was excreted into the medium. No fermentation of glucose was found, but a small amount of D-lactate was detected as a product of endogenous dark metabolism of the cell. All enzymes required for the production of lactate from glucose and from glycogen were found in exponentially growing cells, but the activity of some key enzymes was low or undetectable in old cultures.