New data on the flora of Centrophyceae (Bacillariophyta) in the Neva Bay of the Gulf of Finland (Russia)

This scanning electron microscopy study of phytoplankton from the Neva Bay and analysis of valve images from S.I. Genkal’s iconotheka have provided new data on centric diatoms of the Neva Bay. Representatives of the genera Aulacoseira scalaris and Stephanodiscus lacustris, new to the flora of the Bay, have been identified. The systematic position and distribution of 14 species and varieties of Centrophyceae from the genera Aulacoseira, Conticribra, Cyclostephanos, Ellerbeckia, Handmannia, Pantocsekiella, Stephanodiscus, Thalassiosira have been refined and specified. The species composition of the class Centrophyceae of the Neva Bay has been expanded. Now it includes 42 species and varieties from 17 genera.

Some strains from microalgae collection IBASU-A (Ukraine) as an object of biotechnology

An information on the collection of strains of biotechnological application as an integral part of Microalgal Culture Collection of the M.G. Kholodny Institute of Botany of NAS of Ukraine (IBASU-A) is given. The base of its funds contains some green algal strains belonging to the families of Dunaliellaceae, Chlorellaceae, Scenedesmaceae and Selenastraceae. They have been isolated from different regions of Ukraine in order to find cultures of phototrophic microorganisms – promising for biotechnology, in particular, obtaining biologically active additives for the needs of the food industry, medicine, agriculture, raw materials for the production of biofuels, as well as bioindication, biomonitoring, bioremediation of aquatic objects of the environment, etc. Overall, this special collection includs 90 strains of halophile and freshwater microalgae of 30 species, 15 genera, 7 families, 4 orders, 2 classes. All of them are considered as important objects for industrial cultivation, solution of environmental problems, and the basis for further biotechnological research.

The roles of carbonic anhydrases in сarbon concentrating mechanisms of aquatic photoautotrophs

The article surveys multiple roles of carbonic anhydrases (CAs) in inorganic carbon (Ci) acquisition by cyanobacteria, microalgae, and macrophytes under Ci limiting conditions. Slow Ci diffusion in aquatic environments imposes the need for carbon concentrating mechanisms (also named CO2 concentrating mechanisms, CCMs) in aquatic photoautotrophs to transport Ci against the gradient and ensure CO2 supply to photosynthesis. There are common requirements for efficient CCM functioning in cyanobacteria, algae, and aquatic angiosperms, including active transport of HCO3- to the Ci-concentrating compartment and CO2 generation from the HCO3- pool in the Rubisco-enriched subcompartment. Facilitating Ci diffusion in aqueous solutions and across lipid bilayers, CAs play essential roles in CCMs that are best studied in cyanobacteria, green algae, and diatoms. Roles of CAs in CCMs depend on their localization and include facilitation of active transmembrane Ci uptake by its supplying at the outer surface (Role 1) and removal at the inner surface (Role 2), as well as the acceleration of CO2 production from HCO3- near Rubisco (Role 3) in a special CO2-tight compartment, carboxysome in cyanobacteria or pyrenoid in microalgae. The compartmentalization of CAs is also critical because, if activated in the HCO3- –concentrating compartment, they can easily eliminate the Ci gradient created by CCMs.

The effect of culture medium of Interfillum terricola (J.B.Petersen) Mikhailyuk et al. (Charophyta) on allelopathic, microbiological, agrophysical and agrochemical characteristics of soil

The influence of the cultural medium of the charophyte Interfillum terricola on the allelopathic, microbiological, agrophysical and agrochemical properties of the soil have been studied in model pot experiments. Allelopathic soil regime was assessed by biological testing methods for water-soluble compounds and direct biotesting, as well as by vital indicators of plants-phytometers of winter wheat (Triticum aestivum L., variety "Smuglyanka") and fodder corn (Zea mays L., variety "Kadr 267 MB"). The seeds were sown immediately after the introduction of the culture fluid. The number of germinated seeds was recorded from the 2nd to the 8th day after sowing. The vital condition of phytometer plants was evaluated at the end of the experiments by morphometric indicators of growth (leaf surface area, dry matter biomass of aboveground parts and roots) and the content of photosynthetic pigments in the leaves. When the experiment was completed, soil samples were taken to determine the cytostatic effect of water-soluble compounds and to carry out microbiological and biochemical analyzes. Phenolic compounds were isolated from the soil by ion exchange (desorption) using an ion exchanger KU-2-8 (Н+). In parallel, the electrical conductivity, redox potential, pH and content of nutrients in the soil were determined. The stimulating effect of cultural medium on seed germination, growth and development of assimilation organs of wheat and corn plants has been revealed. The strength of the effect did not depend on the concentration of growing medium, which is characteristic of signal allelopathically active substances. Allelopathic and cytostatic activity of the soil decreased with the use of Interfillum terricola growing medium. The introduction of the cultural fluid significantly affected the number of microorganisms of different ecological and trophic groups. The lowest number of microorganisms was observed at the minimum rate of introduction of microalga medium, and its increase contributed to the growth of the number of almost all studied groups of microorganisms, indicators of transformation and mineralization of organic matter. Under the influence of the cultural medium, the content of phenolic compounds in the soil decreased by 1.1–1.6 times, especially at the norm of 10 mL. The soil treated with cultural fluid had higher rates of transformation and mineralization of organic matter than untreated. The concentration of phenolic compounds in the soil decreased, apparently, due to the activation of the microbiota resulting in the intensification of the destruction processes. An increase in the electrical conductivity of the soil with the introduction of microalgae inoculum was recorded, which may indicate the release of metal ions into the substrate. This confirms the increase in Ca and Mg.

Features of the seasonal succession of phytoplankton in the Crimean coastal area (Black Sea) in years with different climatic conditions (2009–2014)

Under conditions of climatic changes, it is of great interest to study the dynamics of various functional complexes of phytoplankton species. The long-term influence of previous cold winters on the course of the seasonal succession of phytoplankton, as well as the intensity of blooms in the open waters of the Black Sea, were shown earlier. In the coastal zone, this relationship has not yet been sufficiently studied. Based on regular monitoring studies in the coastal area of Sevastopol from 2009–2014, features of the course of seasonal succession of phytoplankton in years with different climatic conditions were revealed: the “cold” years differed from the “warm” ones by a longer dominance of diatom complexes in terms of cell abundance, especially of small-celled species, which characterize the initial stage of seasonal succession of phytoplankton. The level of development of both diatoms and dinoflagellates was minimal compared to other years, with a shift in the periods of maxima to later months. In contrast, the "warm" years were characterized by the predominance of dinoflagellates for most of the study period, with a shift in timing of the maxima to earlier months. Both diatoms and dinoflagellates reached their maximal development in “warm” years in spring and autumn. In the “moderate” years, phytoplankton development proceeded either by analogy with the “cold” (2009) or “warm” (2011) years. The seasonal succession described above is typical for the northwestern Black Sea, in particular, the Sevastopol coastal area, and differs from the average pattern for the northwestern part described earlier for 1992–1993. The difference consisted of an increase in the proportion of stages I and III due to a decrease in stage II compared to 1992–1993.

Dynamics of periphytic Bacillariophyta at different stages of operation of the Chornobyl Nuclear Power Plant cooling pond (Ukraine)

The paper deals with the long-term dynamics of taxonomic composition of diatom periphyton in the Chornobyl nuclear power plant cooling pond (ChNPP cooling pond) at different stages of its operation: before the accident, after the accident and during the present period. The dominant complex of diatoms was marked by the highest diversity in the period after the accident, due to water temperature decreasing and new habitats appearing. The large-scale water-level drawdown in the present period caused the water table to reduce, and the habitats became less diverse. Owing to this, the number of dominant species decreased. Studying the present-day taxonomic composition of periphytic algae in the ChNPP cooling pond by way of light microscopy and scanning electron microscopy made it possible to identify 141 diatom species, represented by 143 infraspecific taxa, from 45 genera, 20 families, 12 orders and 3 classes. 14 species and infraspecific taxa of diatoms from genera Amphora, Cocconeis, Gomphonema, Hippodonta, Karayevia, Navicula, Placoneis, Planothidium, Psammothidium, Sellaphora are new for Ukrainian flora. High contamination of the ChNPP cooling pond with man-made radionuclides 90Sr, 137Cs and the large-scale water-level drawdown did not cause a significant degradation of diatom periphyton, which, in new ecological conditions, is distinguished by high taxonomic diversity and spatial heterogeneity.

Comparative analysis of methods for assessing the safety of Dunaliella salina Teodoresco and Chlorococcum dissectum Korshikov (Chlorophyta) microalgae cultures after exposure to stress factors

The possibility of using various methods for determining the viability of cultures of microalgae Dunaliella salina and Chlorococcum dissectum before and after freezing-warming was investigated and analyzed. It has been established that the selection of an effective method should be carried out individually for each culture. For an integral assessment of the proliferative and metabolic activity of cells of both species of the studied microalgae, Alamar Blue-test and the ability to grow on liquid nutrient media can be used. The use of the Koch plate method, MTT-test and TTC staining is possible only for the microalga C. dissectum. Vital staining with trypan blue was found to be incorrect.

Allelopathic effect of microalgae on winter wheat plants

The results of the study of the allelopathic activity of the culture medium of two species of green and charophyte microalgae (Chlorella vulgaris Beijer. and Interfillum terricola (J.B.Petersen) Mikhailyuk et al.) to winter wheat (Triticum aestivum L.) in model pot experiments with the aim to discover of physiological mechanisms of allelopathy and finding effective and safe compounds with growth-promoting effects. The microalgae culture medium was applied in a rate of 1; 3 and 10 mL per a pot (250 mL) filled with sifted and sterilized gray podzolic soil, before sowing wheat seeds. Test plants were grown in a phytochamber under controlled conditions of light intensity, temperature and soil moisture. The number of germinated seeds was recorded from the 2nd to the 8th day after sowing. The vitality of winter wheat was evaluated at the end of the experiments using morphometric characteristics of growth (height of aboveground parts, leaf surface area, length of root system, number of lateral roots; dry matter mass of aboveground parts and roots) and content of photosynthetic pigments in leaves. At the end of the experiment, the indicators of electrical conductivity, redox potential, pH and content of nutrients in the soil were determined. The positive effect of microalgae on seed germination, growth and photosynthetic apparatus of T. aestivum plants was established. Culture medium of C. vulgaris showed a higher stimulating effect on seed germination and growth of wheat seedlings than I. terricola. The positive effect of microalgae on the photosynthetic activity of wheat and the content of organic carbon in the soil indicates the possibility of developing of biofertilizers based on them in order to improve the structural and functional organization of agroecosystems. The obtained results confirmed the prospects of C. vulgaris as a biofertilizer in crops. The allelopathic effect of I. terricola on vascular plants has been studied for the first time. The important role of indirect allelopathic mechanisms in the interactions between the studied species of microalgae and vascular plants has been established.

On morphological variability of some species of pennate (Bacillariophyta) from the reservoirs of the Chernobyl nuclear power plant exclusion zone (Ukraine)

This scanning electron microscopy study of the morphology of pennate diatoms (Achnanthidium eutrophilum (Lange-Bertalot) Lange-Bertalot, Aneumastis stroesei Mann et Stickle, Gomphonema italicum Kützing, G. pala Reichardt, G. vibrio Ehrenberg, Punctastriata ovalis Williams et Round) from phytoperiphytic communities in the cooling pond of the Chernobyl nuclear power plant and natural lakes of the Exclusion Zone (Glyboke and Daleke lakes) has revealed a higher variability in quantitative characteristics (valve length and width, number of striae in 10 µm). At the same time, no variability of qualitative features (shape of valve, axial and central area, raphe and striae arrangement) has been observed in these species. In A. eutrophilum, the number of striae in 10 µm differ from the published data, in A. stroesei – the valve length, in G. pala, G. vibrio and P. ovalis – the valve length and width. The range of variation in the number of striae in 10 µm in G. pala and the valve length and the number of striae in 10 µm in A. stroesei and G. italicum disagree with the literature data. The first electron micrographs of the inner surface of the valve and the corresponding data on its morphology are obtained for A. eutrophilum, A. stroesei, G. italicum, G. pala and G. vibrio.

The record of the diatom Cymbella australica (A.Schmidt) Cl. in water bodies of Kyiv (Ukraine)

The diatom Cymbella australica was found in some water bodies in research of the algaeflora of Kyiv. The Kyiv population of this species had some discrepancies with the diagnosis (Krammer, 2002) of cell size and coarse structure, which brought it closer to C. tumida (Bréb.) Van Heurck. However, the outlines of the sash clearly separated the Kyiv population of C. australica from C. tumida. It is proposed to expand the diagnosis of C. australica and to consider cell outlines as the only discriminatory feature between C. australica and C. tumida.