scholarly journals Response of Chlorophyll Fluorescence Characteristics and Dissolved Organic Matter for Marine Diatom Skeletonema dohrnii under Stress from Penicillin and Zn2+

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2684
Author(s):  
Yang Liu ◽  
Xiaofang Liu ◽  
Jun Sun
Keyword(s):  
Organic Matter ◽  
Chlorophyll Fluorescence ◽  
Dissolved Organic Matter ◽  
Environmental Stress ◽  
Metal Ion ◽  
Physiological State ◽  
Marine Diatom ◽  
Chlorophyll Fluorescence Characteristics ◽  
Marine Habitats ◽  
Fluorescence Characteristics

Skeletonema dohrnii is a good model diatom for studying environmental stress and has promising applications and prospects in various fields. Antibiotics and heavy metals are commonly exceeded in the nearshore marine habitats. In this work, we investigated the effects of an antibiotic (penicillin, 2 µg/L) and a heavy metal ion (Zn2+, 10 µmol/L) stress on marine diatom S. dohrnii, mainly using excitation-emission matrices (EEMs) fluorescence methods and OJIP test. Results indicated that algal cells grown with the antibiotic showed higher biomass, specific growth rate, doubling time, chlorophyll a, and chlorophyll fluorescence variables. Moreover, excess zinc had negative effects on S. dohrnii. We found that zinc not only inhibited the relative photosynthetic electron transfer efficiency but also reduced the Chl a content, which ultimately affected algal growth and organic matter production. In addition, the combined effect of penicillin and Zn2+ further affected the physiological state of S. dohrnii. The dissolved organic matter (DOM) characteristics of the four cultures were also different, including fluorescence indices (fluorescence index, biological index, β/α, and humification index) and fluorescence peaks (peaks A, C, M and T). In brief, characterization of chlorophyll fluorescence characteristics and DOM-related variables are important for understanding the effects of environmental stress on microalgae.

scholarly journals Cu and Pb accumulation by the marine diatom Thalassiosira weissflogii in the presence of humic acids

2010 ◽  
Vol 7 (3) ◽  
pp. 309 ◽  
Author(s):  
Paula Sánchez-Marín ◽  
Vera I. Slaveykova ◽  
Ricardo Beiras
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Humic Acids ◽  
Metal Ion ◽  
Cell Membranes ◽  
Marine Diatom ◽  
Membrane Properties ◽  
Thalassiosira Weissflogii ◽  
Cell Surfaces ◽  
Free Metal

Environmental context.Dissolved organic matter protects aquatic microorganisms from toxic metals by complexing and decreasing the concentration of the biologically reactive species such as free metal ions. However, there are some cases of enhancement of toxic effects when humic acids are present, which is thought to be due to effects of adsorbed humic acids on cell membranes. For a marine diatom, humic acids adsorbed to cell surfaces enhanced metal adsorption, whereas intracellular metal contents decreased as a result of metal binding by humic acids. These findings suggest that the diatom wall, the frustule, presents a barrier against direct effects of adsorbed humic acids on the plasma membrane. Abstract.Metal complexation by dissolved organic matter, as humic acids, is considered to decrease metal bioavailability by lowering the free metal ion concentration. However, dissolved organic matter adsorption on cell surfaces can modify cell membrane properties, which can also influence metal uptake. Copper and lead accumulation and internalisation by the marine diatom Thalassiosira weissflogii were studied in the absence and presence of humic acids, and adsorption of humic acids to cell surfaces was evaluated. Both Pb and Cu intracellular concentrations decreased in the presence of humic acids according to labile metal concentrations measured by anodic stripping voltammetry, whereas total (intracellular plus adsorbed) metal content was enhanced in the presence of humic acids, probably owing to enhanced metal plus humics adsorption to cell surfaces. The results of the present work stress the importance of differentiating between intracellular and total cellular metal in bioavailability studies, and suggest that the silica frustule of diatoms represents a barrier against humic acids effects on cell membranes.

Features of algae tests of samples containing dissolved organic matter

2020 ◽  
pp. 40-45
Author(s):  
Elena V. Fedoseeva ◽  
Iya Yu. Grigorieva ◽  
Olga V. Nikolaeva ◽  
Vera A. Terekhova
Keyword(s):  
Organic Matter ◽  
Chlorophyll Fluorescence ◽  
Dissolved Organic Matter ◽  
Marine Algae ◽  
Cultivation Conditions ◽  
High Reproducibility ◽  
Test Culture ◽  
Production And Consumption ◽  
Number Of Cells ◽  
Consumption Waste

Algae tests are widely used due to the availability of cultivation conditions and high reproducibility. Freshwater and marine algae are used to estimate the toxicity of drinking, natural and wastewater, water extracts from soils, sewage sludge and production and consumption waste. The presence of dissolved organic matter in the samples, stimulating the growth of algae and the intensity of chlorophyll fluorescence, can significantly affect the result of algae tests, and therefore on the decision on the presence or absence of a toxic effect. When choosing algae as a test culture to determine toxic effects, it is necessary to take into account the possibility of hyperstimulating the number of cells with dissolved organic matter.

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