Multi-biomarker response of cyanobacteria Synechocystis salina and Microcystis aeruginosa to diclofenac.

The cyanobacterial response to pharmaceuticals is less frequently investigated compared to green algae. Pharmaceuticals can influence not only the growth rate of cyanobacteria culture, but can also cause changes at the cellular level. The effect of diclofenac (DCF) as one of the for cyanobacteria has been rarely tested, and DCF has never been applied with cellular biomarkers. The aim of this work was to test the response of two unicellular cyanobacteria (Synechocystis salina and Microcystis aeruginosa) toward DCF (100 mg L-1) under photoautotrophic growth conditions. Such endpoints were analyzed as cells number, DCF uptake, the change in concentrations of photosynthetic pigments, the production of toxins, and chlorophyll a in vivo fluorescence. It was noted that during a 96 h exposure, cell proliferation was not impacted. Nevertheless, a biochemical response was observed. The increased production of microcystin was noted for M. aeruginosa. Due to the negligible absorption of DCF into cells, it is possible that the biochemical changes are induced by an external signal. The application of non-standard biomarkers demonstrates the effect of DCF on microorganism metabolism without a corresponding effect on biomass. The high resistance of cyanobacteria to DCF and the stimulating effect of DCF on the secretion of toxins raise concerns for environment biodiversity.

Harmful algal blooms and their effects in coastal seas of Northern Europe.

Harmful algal blooms (HAB) are recurrent phenomena in northern Europe along the coasts of the Baltic Sea, Kattegat-Skagerrak, eastern North Sea, Norwegian Sea and the Barents Sea. These HABs have caused occasional massive losses for the aquaculture industry and have chronically affected socioeconomic interests in several ways. This status review gives an overview of historical HAB events and summarises reports to the Harmful Algae Event Database from 1986 to the end of year 2019 and observations made in long term monitoring programmes of potentially harmful phytoplankton and of phycotoxins in bivalve shellfish. Major HAB taxa causing fish mortalities in the region include blooms of the prymnesiophyte Chrysochromulina leadbeateri in northern Norway in 1991 and 2019, resulting in huge economic losses for fish farmers. A bloom of the prymesiophyte Prymnesium polylepis (syn. Chrysochromulina polylepis) in the Kattegat-Skagerrak in 1988 was ecosystem disruptive. Blooms of the prymnesiophyte Phaeocystis spp. have caused accumulations of foam on beaches in the southwestern North Sea and Wadden Sea coasts and shellfish mortality has been linked to their occurrence. Mortality of shellfish linked to HAB events has been observed in estuarine waters associated with influx of water from the southern North Sea. The first bloom of the dictyochophyte genus Pseudochattonella was observed in 1998, and since then such blooms have been observed in high cell densities in spring causing fish mortalities some years. Dinoflagellates, primarily Dinophysis spp., intermittently yield concentrations of Diarrhetic Shellfish Toxins (DST) in blue mussels, Mytilus edulis, above regulatory limits along the coasts of Norway, Denmark and the Swedish west coast. On average, DST levels in shellfish have decreased along the Swedish and Norwegian Skagerrak coasts since approximately 2006, coinciding with a decrease in the cell abundance of D. acuta. Among dinoflagellates, Alexandrium species are the major source of Paralytic Shellfish Toxins (PST) in the region. PST concentrations above regulatory levels were rare in the Skagerrak-Kattegat during the three decadal review period, but frequent and often abundant findings of Alexandrium resting cysts in surface sediments indicate a high potential risk for blooms. PST levels often above regulatory limits along the west coast of Norway are associated with A. catenella (ribotype Group 1) as the main toxin producer. Other Alexandrium species, such as A. ostenfeldii and A. minutum, are capable of producing PST among some populations but are usually not associated with PSP events in the region. The cell abundance of A. pseudogonyaulax, a producer of the ichthyotoxin goniodomin (GD), has increased in the Skagerrak-Kattegat since 2010, and may constitute an emerging threat. The dinoflagellate Azadinium spp. have been unequivocally linked to the presence of azaspiracid toxins (AZT) responsible for Azaspiracid Shellfish Poisoning (AZP) in northern Europe. These toxins were detected in bivalve shellfish at concentrations above regulatory limits for the first time in Norway in blue mussels in 2005 and in Sweden in blue mussels and oysters (Ostrea edulis and Crassostrea gigas) in 2018. Certain members of the diatom genus Pseudo-nitzschia produce the neurotoxin domoic acid and analogs known as Amnesic Shellfish Toxins (AST). Blooms of Pseudo-nitzschia were common in the North Sea and the Skagerrak-Kattegat, but levels of AST in bivalve shellfish were rarely above regulatory limits during the review period. Summer cyanobacteria blooms in the Baltic Sea are a concern mainly for tourism by causing massive fouling of bathing water and beaches. Some of the cyanobacteria produce toxins, e.g. Nodularia spumigena, producer of nodularin, which may be a human health problem and cause occasional dog mortalities. Coastal and shelf sea regions in northern Europe provide a key supply of seafood, socioeconomic well-being and ecosystem services. Increasing anthropogenic influence and climate change create environmental stressors causing shifts in the biogeography and intensity of HABs. Continued monitoring of HAB and phycotoxins and the operation of historical databases such as HAEDAT provide not only an ongoing status report but also provide a way to interpret causes and mechanisms of HABs.

Basin-specific changes in filamentous cyanobacteria community composition across four decades in the Baltic Sea.

Almost every summer, dense blooms of filamentous cyanobacteria are formed in the Baltic Sea. These blooms may cause problems for tourism and ecosystem services, where surface accumulations and beach fouling are commonly occurring. Future changes in environmental drivers, including climate change and other anthropogenic disturbances, may further enhance these problems. By compiling monitoring data from countries adjacent to the Baltic Sea, we present spatial and temporal genus-specific distribution of diazotrophic filamentous cyanobacteria (Nostocales) during four decades (1979-2017). While the summer surface salinity decreased with a half up to one unit, the surface temperature in July-August increased with 2-3 °C in most sub-basins of the Baltic Sea, during the time period. The biovolumes of the toxic Nodularia spumigena did not change in any of the sub-basins during the period. On the other hand, the biovolume of the non-toxic Aphanizomenon sp. and the potentially toxic Dolichospermum spp. increased in the northern parts of the Baltic Sea, along with the decreased salinity and elevated temperatures, but Aphanizomenon sp. decreased in the southern parts despite decreased salinity and increased temperatures. These contradictory changes in biovolume of Aphanizomenon sp. between the northern and southern parts of the Baltic Sea may be due to basin-specific effects of the changed environmental conditions, or can be related to local adaptation by sub-populations of the genera. Overall, this comprehensive dataset presents insights to genus-specific bloom dynamics by potentially harmful diazotrophic filamentous cyanobacteria in the Baltic Sea.

The variability of Hg concentration and composition of marine phytoplankton.

Mercury is a toxic element. It undergoes biomagnification in the marine trophic chain, which is why it is significant to identify the factors influencing its bioaccumulation on the first level of the trophic chain. At present, the input of heavy metals to the southern Baltic is being reduced. On the other hand, the parameters influencing mercury remobilisation in the environment are a subject to a long-time trend associated with climate changes. Examples include growing number of heavy rain events causing surges or floods, and increased frequency of storm winds leading to increased coastal erosion as well as overall temperature increase. The present studies were carried out in the coastal zone of the Gulf of Gdansk (southern Baltic) for 18 months at two stations (Chalupy and Oslonino) located in the Puck Lagoon, and for 12 months in Gdynia. Climate changes influence the abundance and species composition of phytoplankton, which in consequence has an effect on Hg accumulation and magnification in the trophic chain, and in the human body as a result. Extreme phenomena such as land erosion or floods resulted in an additional inflow of nutrients, but also toxic substances, into the coastal zone. The bioconcentration factor (BCF) increased almost four times after abrasion of cliff. That was conducive to the growth of microflora, as well as increased Hg accumulation. The highest bioconcentration of Hg in phytoplankton was observed when the Mesodinium rubrum (spring and autumn) and Diatomophyceae (winter) prevailed in biomass. The BCF was then almost tenfold higher than during the rest of the year.

Mercury in the Diatoms of Various Ecological Formations.

Mercury is a neurotoxin, its main source in the human organism being fish and seafood. The first level in the marine food web is formed of planktonic and benthic photosynthetic microorganisms, which form a biofilm on the surface of the hard bottom (epilithon) or plants (epiphyton). They are carriers of nutritional as well as toxic substances and pass these on to subsequent levels of the trophic web. Their biomass is often dominated by diatoms. This was the basis for the presented study into Hg accumulation in epilithic, epiphytic and planktonic diatoms, which was carried out in 2012-2013 in the coastal zone of the Puck Lagoon and the Gulf of Gdansk (southern Baltic). In this coastal area, both micro- and macroorganisms develop particularly intensively. The collected results indicate an increase in Hg concentration in the biofilm during the warm season which, with the lengthening of the vegetative period due to global warming in recent years, is of great significance. As a consequence, the annual mercury load entering the trophic web is larger in comparison with a year in which there is a long, cold winter. An important parameter influencing the accumulation of Hg was the function of those organisms from the biofilm-forming communities. In this case, the highest concentrations of Hg were measured in organisms forming high-profile guilds.

Simple screening technique for determination of adsorbed and absorbed mercury in particulate matter in atmospheric and aquatic environment.

The threat connected to mercury results from its capacity to be transported over long distances and its ability to bioaccumulate and biomagnify in the trophic chain, making it a global problem. Humans are situated at the top of the trophic ladder, and excess mercury manifests itself mainly in the onset of neurological conditions. The toxicity of mercury, as well as its residence time, depends on the form in which it occurs. However, analysis of mercury speciation is time-consuming and poses a high risk of additional or negative contamination. Hence, the mercury thermodesorption method, and particularly its use for fractionating Hg, offers many new possibilities. Here, the thermodesorption technique was applied to the determination of mercury fraction in particulate matter using a DMA-80 direct mercury analyser (Milestone, Italy). The presented method allows direct (without prior mineralisation) determination of labile and stabile mercury fractions within a relatively short time. Heating sample in subsequent temperatures enables determination the share of mercury adsorbed on the surface (mainly associated with halogenides (Hgads1) and HgSO4/HgO/HgF2 (Hgads2), as well as absorbed within the suspended particulate organic matter (Hgabs), in a relatively short time. This fractionation is of great importance in terms of estimating the transfer of mercury to and along the trophic chain. This method determines the contribution of two stable mercury fractions:: HgS and residual Hg, strongly bound to particulate matter matrix (Hgres). The novelty of this technique is also its joint ability to determine gaseous mercury bound to airboirne particulate matter, which will enable better understand Hg cycling in the atmosphere as well as mercury fraction in dry deposition flux. This method enables assessment of global mercury circulation in environment.

Distribution of invasive Cylindrospermopsis raciborskii in the East-Central Europe is driven by climatic and local environmental variables.

Mechanisms behind expansion of an invasive cyanobacterium Cylindrospermopsis raciborskii have not been fully resolved, and different hypotheses, such as global warming, are suggested. In the East-Central Europe, it is widely occurring in western part of Poland but only in single locations in the East due to some limiting factors. Therefore, broad-scale phytoplankton survey including 117 randomly selected lakes in Poland and Lithuania was conducted. The results showed that C. raciborskii occurred widely in western part of Poland but was absent from other regions and Lithuania except one lake. The regions in which C. raciborskii was present had higher annual mean air temperature, higher maximum air temperature of the warmest month and higher minimum temperature of the coldest month, demonstrating that average air temperature, and indirectly, the duration of growing season might be more important factor driving C. raciborskii distribution than measured in situ water temperature. In turn, the presence of C. raciborskii in single localities may be more related to physiological adaptations of separated ecotype. Collectively, these results provide novel evidence on the influence of temperature on C. raciborskii distribution in East-European regions but also indicate high ecological plasticity of this species.

Assessment of the cell biovolume of phytoplankton widespread in coastal and inland water bodies.

The biovolume of phytoplankton must be assessed accurately in order to identify the ecological status of water bodies in line with the WFD requirements. Hence, the current study has been carried out to verify and improve the precision of as well as to facilitate and accelerate estimations of phytoplankton biovolume by reviewing and rearranging the basic geometrical shapes of these organisms applied in such evaluations. The latest standards comprise 17 geometric shapes and equations suitable for estimations of cell/filament/colony biovolume and additionally include taxa-specific 'geometric correction factors' to fit real shapes and 'hidden dimension factors' to achieve data on hardly measureable dimensions. This paper also discusses possible obstacles to making correct biovolume assessments, especially when analyzing taxa of special concern, e.g. Ceratium hirundinella, C. furcoides or Pediastrum duplex and Pseudopediastrum boryanum. Our comparison of two approaches, the previous and the new one, revealed that they yield statistically significantly different biovolume results of these species. Some recommendations how to deal with the new and old methods of biovolume estimations and how to reduce the possibility of errors with overestimation and underestimation were also given. The more recent method can be said to give more precise estimates of phytoplankton biovolume. Besides, it facilitates more rapid phytoplankton analyses in most cases, which is very useful when assessing the ecological status of lakes during routine monitoring programs.

Mercury concentration in phytoplankton in response to warming of an autumn - winter season.

Among other climate changes in the southern Baltic, there is a tendency towards warming, especially in autumn-winter. As a result, the ice cover on the coastal zone often fails to occur. This is conducive to the thriving of phytoplankton, in which metals, including mercury, can be accumulated. The dry deposition of atmospheric Hg during heating seasons is more intense than in non-heating seasons, owing to the combustion of fossil fuels for heating purposes. This has resulted in studies into the role of phytoplankton in the introduction of Hg into the first link of trophic chain, as a function of autumn and winter warming in the coastal zone of the lagoon. The studies were conducted at two stations in the coastal zone of the southern Baltic, in the Puck Lagoon, between December 2011 and May 2013. The obtained results show that, in the estuary region, the lack of ice cover can lead to a 30% increase and during an "extremely warm" autumn and winter an increase of up to three-fold in the mean annual Hg pool in phytoplankton (mass of Hg in phytoplankton per liter of seawater). The Hg content in phytoplankton was higher when Mesodinium rubrum was prevalent in the biomass, while the proportion of dinoflagellates was small.

The use of fosmid metagenomic libraries in preliminary screening for various biological activities.

BACKGROUND: It is generally believed that there are many natural sources of as yet unknown bioactive compounds with a high biotechnological potential. However, the common method based on the use of cell extracts in the preliminary screening for particular molecules or activities is problematic as amounts of obtained compounds may be low, and such experiments are hardly reproducible. Therefore, the aim of this work was to test whether a novel strategy to search for previously unknown biological activities can be efficient. This strategy is based on construction of metagenomic libraries and employment of Escherichia coli strains as cell factories producing compounds of properties potentially useful in biotechnology. RESULTS: Three cyanobacterial metagenomic libraries were constructed in the fosmid system. The libraries were screened for various biological activities. Extracts from selected E. coli clones bearing constructs with fragments of cyanobacterial genomes revealed antimicrobial or anticancer activities. Interestingly, stimulation of growth of host bacteria bearing particular plasmids with certain cyanobacterial genes was detected, suggesting a potential possibility for improvement of E. coli cultivation during biotechnological production. The most interesting plasmids were sequenced, and putative mechanisms of biological effects caused by cyanobacterial gene products are discussed. CONCLUSIONS: The strategy of exploring cyanobacteria as sources of bioactive compounds, based on E. coli cell factories producing compounds due to expression of genes from metagenomic libraries, appears to be effective.

Non-ribosomal peptides produced by Planktothrix agardhii from Siemianówka Dam Reservoir SDR (northeast Poland).

Planktothtrix agardhii (Oscillatoriales) is a filamentous cyanobacterium, which frequently forms blooms in shallow, polymictic and eutrophicated waters. This species is also a rich source of unique linear and cyclic peptides. In the current study, the profile of the peptides in samples from the P. agardhii-dominated Siemianówka Dam Reservoir (SDR) (northeast Poland) was analyzed for four subsequent years (2009-2012). The LC-MS/MS analyses revealed the presence of 33 peptides. Twelve of the most abundant ones, including five microcystins, five anabaenopeptins, one aeruginosin and one planktocyclin, were present in all field samples collected during the study. The detection of different peptides in two P. agardhii isolates indicated that the SDR population was composed of several chemotypes, characterized by different peptide patterns. The total concentration of microcystins (MCs) positively correlated with the biomass of P. agardhii. Between subsequent years, the changes in the ratio of the total MCs concentration to the biomass of P. agardhii were noticed, but they were less than threefold. This is the first study on the production of different classes of non-ribosomal peptides by freshwater cyanobacteria in Poland.