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Many species of microalgae produce a relatively diverse range of metabolites that are interesting for biotechnological applications, and among them exopolysaccharides attract attention due to their structural complexity, biological activities, biodegradability or biocompatibility. An exopolysaccharide of high molecular weight (Mp) of 6.8 × 105 g/mol was obtained by cultivation of the freshwater green coccal microalga Gloeocystis vesiculosa Nägeli 1849 (Chlorophyta). Chemical analyses revealed a dominance of Manp (63.4 wt%), Xylp and its 3-O-Me-derivative (22.4 wt%), and Glcp (11.5 wt%) residues. The results of the chemical and NMR analyses showed an alternating branched 1,2- and 1,3-linked α-D-Manp backbone terminated by a single β-D-Xylp and its 3-O-methyl derivative at O2 of the 1,3-linked α-D-Manp residues. The α-D-Glcp residues were found mainly as 1,4-linked and to a lesser extent as the terminal sugar, indicating partial contamination of β-D-xylo-α-D-mannan with amylose (∼10 wt%) in G. vesiculosa exopolysaccharide.

Sampling of fungi in a grassland on a hill in Rojkov, Central Slovakia, revealed a new species of Luticola (Diadesmidaceae). Its terrestrial populations were found close to the basis of the fertile part of the geoglossoid fungi (Geoglossaceae) that were overgrown with filamentous cyanobacteria of the orders Oscillatoriales and Synechococcales. Luticola rojkoviensis sp. nov. is characterized by the valve outline and the structure of the external valve face: valves are weakly dorsiventrally asymmetrical, rhombic-lanceolate in larger cells to rhombic-elliptic and tri-undulate in smaller cells, with shortly protracted and broadly rounded valve apices. Valve face is minimally concave, as the axial area is lowered and the area around distal raphe elevated. The surface of the valve is mostly uneven due to many depressions, so the external shape of the areolae and the impression of irregular longitudinal rows depend on the extent of these valve ornamentations. Proximal raphe endings are unilaterally slightly deflected, expanded into small central pores. The shape of both the proximal and the distal raphe fissures is slightly asymmetrical. The morphological characteristics of Luticola rojkoviensis sp. nov. are remarkably similar to those of L. hustedtii Levkov, Metzeltin et A.Pavlov, L. ectorii Levkov, Metzeltin et A.Pavlov and L. acidoclinata Lange-Bertalot. The association of Luticola rojkoviensis sp. nov. with geoglossoid fungi and epiphytic cyanobacteria is discussed.

Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by several freshwater species of cyanobacteria. Its high chemical stability and wide biological activity pose a series of threats for human and animal morbidity and mortality. The biggest risk of CYN exposure for human organism comes from the consumption of contaminated water, fish or seafood. Very important for effective monitoring of the occurrence of CYN in aquatic environment is accurate identification of cyanobacteria species, that are potentially able to synthesize CYN. In this review we collect data about the discovery of CYN production in cyanobacteria and present the morphological changes between all its producers. Additionally we set together the results describing the catalytic decomposition of CYN.

Among littoral mats of an irrigation canal in South Slovakia, long filaments of a heterocytous cyanobacterium were found that were longitudinally attached to filaments of Mougeotia sp. and the centric diatom Aulacoseira italica (Ehrenberg) Simonsen. Similar heterocytous taxa attached to other algae have been described, but without akinetes, so their life cycle is incompletely known and their taxonomic position remains unclear. The presence of a sheath and the observation of solitary akinetes allowed us to classify our specimens as a representative of the genus Aulosira Bornet et Flahault. Our study lead us to propose a new combination — Aulosira epiphytica (Gardner) Hindakova et Hindak, comb. nova, using Nodularia epiphytica Gardner 1927 as basionym.

Microflora of cyanobacteria and algae of small forest dystrophic Lake Sęczek located in the Masurian Lake District, NE Poland, was investigated in 2012 and 2013. A total of 16 genera with 7 species of cyanobacteria and 56 genera with 74 species, 6 varietas and forms of algae were determined. Most of them represented commonly occurring microorganisms of slightly acidic waters, but some of them are considered rare, i.e. the oscillatorian cyanobacterium Katagnymene accurata Geitler (for the first time found in Poland), and green algae Coenochloris sphagnicola Hindák, Mucidosphaerium sphagnale (Hindák) C. Bock, Pröschold et Krienitz, Closterium navicula (Bréb.) Lütkem., and Cosmarium cf. aphaerosporum var. corribense (W. et G.S. West) Krieger et Gerloff., which are described in more detail. As regards the species diversity, the plankton of the lake was rather species-poor in contrast to the algal communities in the Sphagnum littoral.

The seasonal development of the phytoplankton, phytobenthos, zooplankton, and microbenthos in a high eutrophised intravilan water reservoir was studied. Finally, 25 genera with 44 species of Cyanobacteria/Cyanophytes and 67 genera with 102 species as well as infraspecific taxa of different groups of microscopic algae were identified. The phytoplankton in most parts of the water basin was strongly dominated by green colonial alga Golenkiniopsis longispina. From October until December a cyanophyte species Aphanocapsa delicatissima with typical cell dimensions of picoplankton/ was found in large amounts/predominated. As early as spring, a plankton bloom in all its components was observed. At that time, also a high concentration of total phosphorus was recorded, which in the second half of April dropped rapidly. The concentration of chlorophyll-a increased from 162.7 μg/L in March to 2322 μg/L in September. Massive occurrence of benthic protozoa in the plankton, as a consequence of anoxia, has been observed. Further, the detritivore and omnivore ciliate species Coleps hirtus dominated in the microbenthos. Altogether 74 of ciliate taxa were detected. Their abundance and biomass reached peak in April, but these steadily decreased from May until the end of the year. Extreme values of zooplankton density (54,016 ind/L) were recorded in spring followed by a sudden fall in summer and autumn. The contribution of rotifers (Brachionus spp., Filinia longiseta) in the total zooplankton density and biomass was 98%. Relatively a low species richness of crustaceans (4 Cladocera and 3 Copepoda) was observed.

We studied the diversity of the photosynthetic microscopic epilithon overgrowing the concrete walls of a cooling tower of the power plant at Bełchatów, central Poland. Epilithon samples were collected from the open upper part of concrete walls of a cooling tower in March 2006 and examined in labs as dried material in September 2006, and again in March 2011. The aerophytic assemblages were strongly dominated by a nostocalean cyanobacterium, Scytonema myochrous C. Agardh ex Bornet et Flahault. Other cyanobacteria and algae occurred very sporadically and in low abundance. The trichome morphology of S. myochrous growing directly on the tower differs considerably from that of lab-cultured ones. Trichomes from field material were very long, conspicuously sheathed and dark brown, with relatively sparse ramification and with cylindrical cells and heterocytes. Trichomes cultivated in the laboratory were shorter and thicker, with thin, hyaline sheaths which were not layered; they were frequently ramified, and the cells and heterocytes were discoid. Besides Scytonema myochrous, the first revitalized cyanobacteria growing in laboratory conditions included Nostoc sp., Leptolyngbya gracillima (Zopf ex Hansgirg) Anagnostidis et Komárek, and Gloeothece rupestris (Lyngbye) Bornet in Witrock et Nordstedt.

The invasion and spread of non-native species of many different kinds of organisms is of increasing interest to researchers. Invasions by microscopic organisms, however, are poorly understood, and their impact on the environment is probably underestimated. We collected available data on non-native and invasive/expansive algae and cyanobacteria in the Czech Republic; we mapped their distribution and assessed their impact on local species and other real or potential risks resulting from their spread. The list of alien species in the Czech Republic contains 10 species of cyanobacteria, 9 species of Bacillariophyceae, 1 species of Dinophyta, 1 species of Ulvophyceae, 2 species of Chlorophyceae, and 1 species complex of Zygnematopyceae. The literature on the worldwide occurrence of these taxa is also reviewed.

The morphology of Makinoella tosaensis Okada 1949, a chlorococcalean coenobial alga described from Japan and since then observed only in Korea, has been studied under the LM from field material and in laboratory cultures. Its collection from a small fountain in the campus park of the Slovak Academy of Sciences in Bratislava, Slovakia, is the first record outside East Asia. The morphology of coenobia and cells in this material is in agreement with published data of the species.

The cell morphology of Achnanthes thermalis var. rumrichorum Lange-Bertalot, a first record for the territory of Slovakia and in Europe, was studied under LM and SEM and documented by micrographs. This diatom was found in the benthos of a gravel-pit lake in Bratislava and in artificial thermal basins in the health-resort park of Piesťany, Western Slovakia. A discussion of the morphological features of this taxon and their taxonomic affinities with related species is presented.

The morphologies of 15 rare chlorococcalean algae, i.e. three species of the Characiaceae [Hydrianum crassiapex Korshikov, H. viride (Scherffel) H. Ettl, Characiellopsis skujae (Fott) Komarek], four taxa of the genus Pediastrum Meyen [Pediastrum privum (Printz) E. Hegewald, P. duplex Meyen var. rugulosum Raciborski, P. angulosum (Ehrenberg) ex Meneghini, Pediastrum biradiatum Meyen], a radiococcalean alga Phacomyxa sphagnicola Skuja, Pseudodictyosphaerium fluviatile (Hindak) Hindak from the Dictyosphaeriaceae, three representatives of the family Oocystaceae (Amphikrikos minutissimus Korshikov, Gloeotaenium loitlesbergianum Hansgirg, Chlorolobion obtusum Korshikov) and three species of the genus Scenedesmus Meyen (S. ginzbergeri Kammerer, S. incrassatulus Bohlin, S. parisiensis Deflandre), are documented by drawings and micrographs and their taxonomy is discussed. Of these, Hydrianum viride, Pediastrum duplex var. rugulosum, Scenedesmus ginzbergeri and S. parisiensis are recorded for the first time in Slovakia.

This paper presents data on the diversity of cyanobacteria and algae of nine gravel pit lakes situated within the city boundaries of Bratislava, W Slovakia. During more than 30 years of investigations 187 genera and 591 infrageneric taxa were determined, of which 40 genera and 58 species belong to Cyanobacteria, and 147 genera, 492 species, 2 subspecies, 35 varieties and 4 forms belong to various groups of algae. From gravel and sand pit lakes in Slovakia several new taxa were established, e.g. Cyanocatena planctonica Hindak, 1975 and Planktocyanocapsa stagnalis Hindak, 2002 from the cyanobacteria, or Catenococcus tortuosus Hindak, 1977, Posonia sestonica Hindak, 1982 and Catenocystis gerulata Hindak, 1988 from the chlorophytes. Many taxa found were new records for this country. The floristic composition of the lakes investigated was rich but due to the uniformity of environmental conditions more or less similar. The majority of the taxa were diatoms, while the chlorophytes represented about 22%. As a whole, the taxonomic structure is typical of mesotrophic to eutrophic, slightly saline water of temperate zones, but some taxa may be considered characteristic of oligotrophic lakes.

The genus Synechococcus represents an enigmatic group of cyanobacteria with very simple unicellular morphology and polyphyletic evolutionary origin. Here, we describe a new genus based on strain of Synechococcus-like cyanobacterium. The strain was isolated from the peat bog Klin (Slovakia), where it occupies different niches such as hyaline cells of Sphagnum, sheaths of cyanobacteria, dead cells of desmids, carapaces of dead crustaceans, and solitary in detritus. We describe this new genus using a combination of molecular, morphological and ecological features. A phylogeny of the 16S rRNA gene, 16S-23S ITS and rbcL loci showed a separate position of the investigated strain and its close proximity to filamentous cyanobacteria. Therefore, it is a novel lineage of Synechococcus-like cyanobacteria illustrating the polyphyletic nature of the genus Synechococcus. Moreover, the strain exhibits unique morphological and ecological features, which allow us to erect the new monospecific genus Neosynechococcus.

Morphology, ultrastructure and formation of resting cysts of E. agilis H.J. Carter and E. anabaena Mainx are described. The SEM micrographs of cysts of E. anabaena and E. agilis are presented for the first time. Information on the neuston film formed by these species is given. An ecological database and list of accompanying species is also included.