Effects of light intensity, temperature, and salinity in allelopathic interactions between coexisting Synechococcus sp. phenotypes.

Organisms from the Synechococcus genus constitute one of the major contributors to oceanic primary production, broadly distributed in waters with wide range of environmental conditions. This work investigated the influence of abiotic factors (temperature, irradiance, and salinity) on the strength of allelopathic interactions between different phenotypes of picoplanktonic cyanobacteria of the genus Synechococcus sp. (Type 1, Type 2, and Type 3a) employing mixed cultures and cell-free filtrate assays. The response variables studied were population growth and content of photosynthetic pigments: chlorophyll a (Chl a), carotenoids (Car), phycocyanin (PC), phycoerythrin (PE), and allophycocyanin (APC). Temperature was shown to be the most significant abiotic factor impacting the allelopathy of Synechococcus sp. phenotypes, with the Type 2 most significantly impacted. Irradiance also had a significant effect, having the largest effect on allelopathy of Type 3a phenotype. Changes in salinity had the greatest effect on allelopathy of Type 1. Our study has shown the significant influence of temperature, irradiance, and salinity on the strength of allelopathic compounds secreted by Synechococcus sp. phenotypes, with temperature the most significantly affecting allelopathic properties. Moreover, we discovered that the allelopathic response to changing environmental factors is highly phenotype-specific. This differential response of allelopathy could help different phenotypes of Synechococcus sp. to coexist in the water column.

Macroalgal Defense against Competitors and Herbivores.

Macroalgae are the source of many harmful allelopathic compounds, which are synthesized as a defense strategy against competitors and herbivores. Therefore, it can be predicted that certain species reduce aquaculture performance. Herein, the allelopathic ability of 123 different taxa of green, red, and brown algae have been summarized based on literature reports. Research on macroalgae and their allelopathic effects on other animal organisms was conducted primarily in Australia, Mexico, and the United States. Nevertheless, there are also several scientific reports in this field from South America and Asia; the study areas in the latter continents coincide with areas where aquaculture is highly developed and widely practiced. Therefore, the allelopathic activity of macroalgae on coexisting animals is an issue that is worth careful investigation. In this work, we characterize the distribution of allelopathic macroalgae and compare them with aquaculture locations, describe the methods for the study of macroalgal allelopathy, present the taxonomic position of allelopathic macroalgae and their impact on coexisting aquatic competitors (Cnidaria) and herbivores (Annelida, Echinodermata, Arthropoda, Mollusca, and Chordata), and compile information on allelopathic compounds produced by different macroalgae species. This work gathers the current knowledge on the phenomenon of macroalgal allelopathy and their allelochemicals affecting aquatic animal (competitors and predators) worldwide and it provides future research directions for this topic.

Changes in Growth, Photosynthesis Performance, Pigments, and Toxin Contents of Bloom-Forming Cyanobacteria after Exposure to Macroalgal Allelochemicals.

Macroalgae can directly restrict the growth of various phytoplankton species by releasing allelopathic compounds; therefore, considerable attention should be paid to the allelopathic potential of these organisms against harmful and bloom-forming cyanobacteria. The main aim of this study was to demonstrate for the first time the allelopathic activity of Ulva intestinalis on the growth, the fluorescence parameters: the maximum PSII quantum efficiency (Fv/Fm) and the effective quantum yield of PSII photochemistry (ΦPSII), the chlorophyll a (Chl a) and carotenoid (Car) content, and the microcystin-LR (MC-LR) and phenol content of three bloom-forming cyanobacteria, Aphanizomenon sp., Nodularia spumigena, and Nostoc sp. We found both negative and positive allelopathic effects of U. intestinalis on tested cyanobacteria. The study clearly showed that the addition of the filtrate of U. intestinalis significantly inhibited growth, decreased pigment content and Fv/Fm and ΦPSII values of N. spumigena and Nostoc sp., and stimulated Aphanizomenon sp. The addition of different concentrations of aqueous extract also stimulated the cyanobacterial growth. It was also shown that the addition of extract obtained from U. intestinalis caused a significant decrease in the MC-LR content in Nostoc sp. cells. Moreover, it the phenol content in N. spumigena cells was increased. On the other hand, the cell-specific phenol content for Aphanizomenon sp. decreased due to the addition of the filtrate. In this work, we demonstrated that the allelopathic effect of U. intestinalis depends on the target species' identity as well as the type of allelopathic method used. The study of the allelopathic Baltic macroalgae may help to identify their possible role as a significant biological factor influencing harmful cyanobacterial blooms in brackish ecosystems.

The current state of knowledge on taxonomy, modulating factors, ecological roles, and mode of action of phytoplankton allelochemicals.

Allelopathy is widespread in marine, brackish, and freshwater habitats. Literature data indicate that allelopathy could offer a competitive advantage for some phytoplankton species by reducing the growth of competitors. It is also believed that allelopathy may affect species succession. Thus, allelopathy may play a role in the development of blooms. Over the past few decades, the world's coastal waters have experienced increases in the numbers of cyanobacterial and microalgal blooming events. Understanding how allelopathy is implicated with other biological and environmental factors as a bloom-development mechanism is an important topic for future research. This review focuses on a taxonomic overview of allelopathic cyanobacteria and microalgae, the biological and environmental factors that affect allelochemical production, their role in ecological dynamics, and their physiological modes of action, as well as potential industrial applications of allelopathic compounds.

Assessment of the Allelochemical Activity and Biochemical Profile of Different Phenotypes of Picocyanobacteria from the Genus Synechococcus.

Organisms belonging to Synechococcus sp. genera are observed in all freshwater, brackish, and marine waters of the world. They play a relevant role in these ecosystems, since they are one of the main primary producers, especially in open ocean. Eventually, they form mass blooms in coastal areas, which are potentially dangerous for the functioning of marine ecosystems. Allelopathy could be an important factor promoting the proliferation of these organisms. According to the authors' best knowledge, there is no information on the allelopathic activity and allelopathic compounds exhibited by different Synechococcus sp. phenotypes. Therefore, the research conducted here aimed to study the bioactivity of compounds produced by three phenotypes of Synechococcus sp. by studying their influence on the growth, chlorophyll fluorescence, and photosynthetic pigments of eighteen cyanobacteria and microalgae species. We demonstrated that three different Synechococcus sp. phenotypes, including a phycocyanin (PC)-rich strain (Type 1; green strain) and phycoerythrin (PE)-rich strains containing phycoerythrobilin (PEB) and phycocyanobilin (PCB) (Type 2; red strain and Type 3a; brown strain), had a significant allelopathic effect on the selected species of cyanobacteria, diatoms, and green algae. For all green algae, a decrease in cell abundance under the influence of phenotypes of donor cyanobacteria was shown, whereas, among some target cyanobacteria and diatom species, the cell-free filtrate was observed to have a stimulatory effect. Our estimates of the stress on photosystem II (Fv/Fm) showed a similar pattern, although for some diatoms, there was an effect of stress on photosynthesis, while a stimulatory effect on growth was also displayed. The pigment content was affected by allelopathy in most cases, particularly for chlorophyll a, whilst it was a bit less significant for carotenoids. Our results showed that Synechococcus sp. Type 3a had the strongest effect on target species, while Synechococcus sp. Type 1 had the weakest allelopathic effect. Furthermore, GC-MS analysis produced different biochemical profiles for the Synechococcus strains. For every phenotype, the most abundant compound was different, with oxime-, methoxy-phenyl- being the most abundant substance for Synechococcus Type 1, eicosane for Synechococcus Type 2, and silanediol for Synechococcus Type 3a.

Growth phase-dependent biochemical composition of green microalgae: Theoretical considerations for biogas production.

One of the most efficient and promising technique for biofuel production from microalgae biomass is an anaerobic fermentation. The goal of this work was to investigate changes in the biochemical composition during the long-term cultivation period of 15 green microalgal strains originating from the Baltic Sea. Subsequently, their theoretical methane potential (TMP), which is strictly determined by an algal growth phase and thus physiological state, was established. Based on the full spectrum of changes in the percentage share of lipids, carbohydrates, and proteins in biomass, it was shown that the TMP values differed among strains as well as fluctuated during cultivation. The common trend, i.e., lipids accumulation and proteins breakdown in the late growth phase, was observed for most of the strains; others, however, preferred carbohydrates as storage material. The TMP data obtained herein allows developing a strategy for the design and production of algal biomass biochemically suited for fermentation.

Physiological Effects on Coexisting Microalgae of the Allelochemicals Produced by the Bloom-Forming Cyanobacteria Synechococcus sp. and Nodularia Spumigena.

Only a few studies have documented the physiological effects of allelopathy from cyanobacteria against coexisting microalgae. We investigated the allelopathic ability of the bloom-forming cyanobacteria Synechococcus sp. and Nodularia spumigena filtrates on several aspects related to the physiology of the target species: population growth, cell morphology, and several indexes of photosynthesis rate and respiration. The target species were the following: two species of green algae (Oocystis submarina, Chlorella vulgaris) and two species of diatoms (Bacillaria paxillifer, Skeletonema marinoi). These four species coexist in the natural environment with the employed strains of Synechococcus sp. and N. spumigena employed. The tests were performed with single and repeated addition of cyanobacterial cell-free filtrate. We also tested the importance of the growth phase in the strength of the allelopathic effect. The negative effects of both cyanobacteria were the strongest with repeated exudates addition, and generally, Synechococcus sp. and N. spumigena were allelopathic only in the exponential growth phase. O. submarina was not negatively affected by Synechococcus filtrates in any of the parameters studied, while C. vulgaris, B. paxillifer, and S. marinoi were affected in several ways. N. spumigena was characterized by a stronger allelopathic activity than Synechococcus sp., showing a negative effect on all target species. The highest decline in growth, as well as the most apparent cell physical damage, was observed for the diatom S. marinoi. Our findings suggest that cyanobacterial allelochemicals are associated with the cell physical damage, as well as a reduced performance in respiration and photosynthesis system in the studied microalgae which cause the inhibition of the population growth. Moreover, our study has shown that some biotic factors that increase the intensity of allelopathic effects may also alter the ratio between bloom-forming cyanobacteria and some phytoplankton species that occur in the same aquatic ecosystem.

Allelopathic and Bloom-Forming Picocyanobacteria in a Changing World.

Picocyanobacteria are extremely important organisms in the world's oceans and freshwater ecosystems. They play an essential role in primary production and their domination in phytoplankton biomass is common in both oligotrophic and eutrophic waters. Their role is expected to become even more relevant with the effect of climate change. However, this group of photoautotrophic organisms still remains insufficiently recognized. Only a few works have focused in detail on the occurrence of massive blooms of picocyanobacteria, their toxicity and allelopathic activity. Filling the gap in our knowledge about the mechanisms involved in the proliferation of these organisms could provide a better understanding of aquatic environments. In this review, we gathered and described recent information about allelopathic activity of picocyanobacteria and occurrence of their massive blooms in many aquatic ecosystems. We also examined the relationships between climate change and representative picocyanobacterial genera from freshwater, brackish and marine ecosystems. This work emphasizes the importance of studying the smallest picoplanktonic fractions of cyanobacteria.

[Patented photobioreactor to commercial production of new drugs and nutraceuticals from microalgae]. / Opatentowany fotobioreaktor do produkcji nowych leków i nutraceutyków wytwarzanych na bazie mikroalg.

Microalgae - microscopic photosynthetic plants are an inexhaustible source of compounds with potential pharmaceutical applications. However, the development of microalgal biotechnology in particular for the production of new drugs and nutraceuticals has been slowed by the limited growth performance of algae in industrial photobioreactors. This is due to low light intensity, necessary for photosynthesis, which causes growth of algae. Flat-Plate photobioreactor with a solar-tracker system which is reported to protect with the Patent Office of RP enables optimal positioning of culture vessel to the direction of the sun's rays and thus can increase the efficiency of biomass growth (by 30%) and lipid content, compared with photobioreactors without it. The use of the invention in industrial plants can significantly contribute to lower costs and make all the technology more profitable.

Acute toxicity assessment of perfluorinated carboxylic acids towards the Baltic microalgae.

The presence of high-energy carbon-fluorine bonds in perfluoro compounds lends them great stability and causes them to be environmentally persistent. Relatively little is known about the acute toxicity of perfluorinated carboxylic acids (PFCAs) to ecotoxicological markers such as aquatic plants and animals. This study tested the toxicity of these compounds to the green alga Chlorella vulgaris, the diatom Skeletonema marinoi and the blue-green alga Geitlerinema amphibium, which are species representative of the algal flora of the Baltic Sea. The EC(50) values obtained range from 0.28 mM to 12.84 mM. A distinct relationship between hydrophobicity and toxicity is demonstrated. For every extra perfluoromethylene group in the alkyl chain, the toxicity increases twofold. LogEC(50) values are very well correlated linearly with both the number of carbon atoms in the perfluoroalkyl chain and the partition coefficients. The results also indicate that there are clear differences between the responses of particular taxonomic groups of algae: blue-green algae and diatoms are far more sensitive to PFCAs than green algae, probably because of differences in cell wall structure.

Comparison of green algae Cladophora sp. and Enteromorpha sp. as potential biomonitors of chemical elements in the southern Baltic.

The contents of Cd, Cu, Ni, Pb, Zn, Mn, K, Na, Ca and Mg were determined in the green algae Cladophora sp. from coastal and lagoonal waters of the southern Baltic. Factor analysis demonstrated spatial differences between concentration of chemical elements. The algae from the southern Baltic contained more Na and K while the anthropogenic impact of Cu, Pb and Zn was observed in the case of Cladophora sp. and Enteromorpha sp. from the Gulf of Gdansk at the vicinity of Gdynia. This area is exposed to emission of heavy metals from municipal and industrial sources with the main contribution of shipbuilding industry and seaport. The statistical evaluation of data has demonstrated that there exists a correlation between concentrations of Cu, Pb and Zn in both green algae collected at the same time and sampling sites of the Gulf of Gdansk. Our results show that in the case of absence of one species in the investigated area it is still possible to continue successfully the biomonitoring studies with its replacing by second one, i.e. Cladophora sp. by Enteromorpha sp. and vice versa; in consequence reliable results may be obtained.

Distribution and relationships between selected chemical elements in green alga Enteromorpha sp. from the southern Baltic.

The concentrations of heavy metals (Cd, Cu, Ni, Pb, Zn and Mn) and macroelements (K, Na, Ca and Mg) were determined in green alga Enteromorpha sp. from the coastal zone of the southern Baltic including Gulf of Gdansk and Vistula Lagoon in 2000-2003. In order to estimate the degree of accumulation of each element by the green alga, concentration and discrimination factors (CFs) with respect to seawater were calculated. The results of factor analysis (FA) and ANOVA clearly indicate geographical differences between concentrations of chemical elements. Enteromorpha sp. from Vistula Lagoon and the southern Baltic exhibited higher levels of Mn and Ni, and Na and K, respectively. Anthropogenic impact of Cu, Pb and Zn, possibly originated from municipal sewage, was identified in alga samples collected in the Gulf of Gdansk, especially in the vicinity of Gdynia. From comparison our data with those published earlier results that Pb content in Enteromorpha sp. from the Gulf of Gdansk decreased within 1978-2003 reflecting reducing use of leaded petrol in Baltic countries in this period. The alga Enteromorpha sp. can be used for biomonitoring surveys of metal contaminants in coastal areas of the Baltic Sea.

Marine toxicity assessment of imidazolium ionic liquids: acute effects on the Baltic algae Oocystis submarina and Cyclotella meneghiniana.

Interest in ionic liquids for their potential in different chemical processes is increasing, as they are claimed to be environmentally benign and are very good non-volatile solvents for a wide range of applications. With regard to their physical and chemical characteristics, the properties of ionic liquids can be modified over a wide range because the cation's fine structure and the anion's identity can be altered. Since millions of ion combinations are possible it is of the highest importance to outline rational guidelines to develop technologically suitable but also environmentally harmless ionic liquids. This paper presents the results of a preliminary assessment of the toxicity of selected imidazolium ionic liquids towards marine algae. The selection of chemical entities was based on the t-SAR approach (thinking in terms of structure-activity relationships) focusing on the length (C(2)

[Fungi growth in buildings]. / Wystepowanie grzybów strzepkowych w obiektach budowlanych.

The results of research into occurrence of fungi in buildings are hereby presented. Indoor air pollution balanced between 10(2)-10(3) cfu/m3. Examined building surfaces have been found significantly mouldy. Total number of fungi ranged from 3.28 x 10(5) to 9.75 x 10(10) cfu/100 cm2. The results of the research show the active development of this group of microorganisms. In rooms, over 30 fungi species belonging to 11 genera have been detected. The most frequently occurring ones were fungi genera: Cladosporium, Penicillium, Aspergillus and Acremonium. Among those, potentially toxinogenic species have been separated (Aspergillus ochraceus, Cladosporium cladosporioides, Penicillium chrysogenum, Penicillium notatum). Apart from micotoxins they have been found to produce huge amounts of conidia which can cause allergy in sensitive people. Hence, people should definitely avoid fungi in their environment.