Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES FROM BASCIFLIK POTATO

Potato (Solanum tuberosum L.) is a significant vegetable and one of the most widely consumed crops.Photochemical investigation revealed that the potatoes had antibacterial, anticancer and antioxidantproperties. In this study, Basciflik Potato Genotype (BPG) was used for the synthesis of silver nanoparticles.The BPG was extracted with distilled water. After filtration, the solution was treated with silver nitrate at50°C to yield silver nanoparticles (AgNPs). The color change indicated the formation of AgNPs. Moreover,the structure AgNPs was elucidated by spectroscopic techniques such as Fourier transform infraredspectroscopy (FTIR), Ultraviolet-visible (UV-Vis), X-ray diffraction (XRD), and Scanning electronmicroscope (SEM). The characteristic functional groups were presented by FTIR. The signal observed at3267 cm-1 corresponded to the hydroxyl group. The absorption at 430 nm in UV-Vis spectrum showedestablishment of AgNPs. The crystalline structure of AgNPs was confirmed by XRD analysis. SEM analysisalso revealed the desired product with the average size of 37.31 nm. The antibacterial activity of AgNPs wascarried out using Staphylococcus aerus, Salmonella Enteritidis, Escherichia coli, Listeria monocytogenesbacteria. The AgNPs have considerable antibacterial activity at Minimum Inhibition Concentration (MIC),0.5 mg/mL except for E. coli which revealed the activity at 0.25 mg/mL.</p

Biogenic synthesis of silver nanoparticles using Sambucus nigra leaves: elucidation, antimicrobial, antioxidant activities and quantification of phenolics

Biogenic production of silver nanoparticles (sn-AgNPs) was accomplished by Sambucus nigra. The identification of structures was performed by a wide spectroscopic study. Ultraviolet–visible (UV–Vis) spectroscopic study indicated the maximum absorption of nanoparticles at 480 nm. Scanning electron microscopy (SEM) presented the nanoparticles as spherical shapes. X-ray diffraction (XRD) signals (2θ) at the degrees of 38.20°, 44.40°, 64.61°, 77.61°, and 81.76° corresponded to [111, 020, 202, 131, and 222] facet, respectively, confirming the nanostructure as face-centered cubic structure. The size of the nanoparticles was determined as 28.6 nm and 27.4 nm by SEM and TEM images, respectively. Zeta potential presented the stability of the product (− 51.3 mV). Furthermore, the histogram of dynamic light scattering (DLS) displayed the particle size of the nanostructure as 31.01 nm. HPLC analysis was used to determine the phenolics in S. nigra aerial part quantitatively and chlorogenic acid was the main product (10.76 mg/g extract). sn-AgNPs showed the substantial antioxidant effect as 12.1 ± 0.19 (µg/mL, lC50) and 3.1 ± 0.1 (lC50) for DPPH• and ABTS•+ assays, respectively. Antibacterial activity of extract and sn-AgNPs was executed. Both extract and Sn-AgNPs exhibited considerable activity

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.Peer reviewe

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L−1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4°C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature