The Effect of Copper and Selenium Nanocarboxylates on Biomass Accumulation and Photosynthetic Energy Transduction Efficiency of the Green Algae Chlorella Vulgaris

Abstract

Nanoaquachelates, the nanoparticles with the molecules of water and/or carboxylic acids as ligands, are used in many fields of biotechnology. Ultra-pure nanocarboxylates of microelements are the materials of spatial perspective. In the present work, the effects of copper and selenium nanoaquachelates carboxylated with citric acid on biomass accumulation of the green algae Chlorella vulgaris were examined. Besides, the efficiency of the reactions of the light stage of photosynthesis was estimated by measuring chlorophyll a fluorescence. The addition of 0.67–4 mg L−1 of Cu nanocarboxylates resulted in the increase in Chlorella biomass by ca. 20%; however, their concentrations ranging from 20 to 40 mg L−1 strongly inhibited algal growth after the 12th day of cultivation. Se nanocarboxylates at 0.4–4 mg L−1 concentrations also stimulated the growth of C. vulgaris, and the increase in biomass came up to 40–45%. The addition of Se nanocarboxylates at smaller concentrations (0.07 or 0.2 mg L−1) at first caused the retardation of culture growth, but that effect disappeared after 18–24 days of cultivation. The addition of 2–4 mg L−1 of Cu nanocarboxylates or 0.4–4 mg L−1 of Se nanocarboxylates caused the evident initial increase in such chlorophyll a fluorescence parameters as maximal quantum yield of photosystem II photochemistry (F v/F m) and the quantum yield of photosystem II photochemistry in the light-adapted state (F v'/F m'). Photochemical fluorescence quenching coefficients declined after 24 days of growth with Cu nanocarboxylates, but they increased after 6 days of the addition of 2 or 4 mg L−1 Se nanocarboxylates. Those alterations affected the overall quantum yield of the photosynthetic electron transport in photosystem II.

Nanoparticle Exposure and Hormetic Dose–Responses: An Update

“…The hormetic phenomenon described by Zhu et al [ 23 ] was also confirmed by the results obtained with Cu nano-aquachelates carboxylated with citric acid on the biomass accumulation of the green algae Chlorella vulgaris [ 24 ]. This latter finding may be dependent on the increase in inorganic copper concentration which may impair biochemical and physiological processes in algal cells.…”

“…For example, stimulatory action of Ag-NPs was greater for NP formulations with a smaller diameter in human cell [ 12 ], plant [ 26 ] and larval models [ 34 ], than for NPs with a greater size [ 13 ]. Therefore, it can be speculated that factors other than size, including the original state of the material, e.g., powder vs. colloidal dispersion [ 12 ], the NP chemical composition [ 14 , 16 , 23 , 24 ] ( Figure 4 ), the agglomeration status [ 12 ], and ENM surface functionalization [ 13 , 16 , 26 ] ( Figure 4 ), should be considered as possible key factors in the hormetic response to NP insults.…”

“…In the same experimental model, increasing concentrations of CdSe/ZnS-QDs did not induced a hormetic response (modified by Morelli et al [ 46 ]). ( E , F ) Cu-NPs and Se-NPs induced a different kind of biphasic response related to the grown of Chlorella vulgaris (modified by Mykhaylenko and Zolotareva, [ 24 ]). * Indicates statistical significance ( p < 0.05).…”

Effects of Cu²⁺ and Hg²⁺ on Growth and Photosynthesis of Two <i>Scenedesmus</i> Species

“…Similar to previous reports [8,30], treatments with Cu 2+ depressed cell growth and decreased contents of photosynthetic pigments (chl-a, car or chl-b) in S. quadricauda and S. acutus, demonstrating that high levels of Cu 2+ triggered severe environmental concerns. A high level of Cu 2+ blocked the electron transport and subsequently inhibited PSII activity [31], which further decreased F ν /F m and adversely affected photosynthesis of algae [31][32][33][34][35]. In the present study, treatments with high levels of Cu 2+ decreased contents of photosynthetic pigments, rETR max and I k in both S. quadricauda and S. acutus, suggesting that the photosynthetic process was inhibited.…”

Biosorption combined with lipid production and growth inhibition of copper on the microalgal Pediastrum sp.

“…Previous studies have reported that Cu is an essential nutrient to nearly all species from animal to algae [15,16]. However, high concentration of Cu in water environment may result in toxicity to aquatic organisms [17]. In addition, Cu can generate various toxic effects on different aquatic species [18].…”