Quantification of silver nanoparticle toxicity to algae in soil via photosynthetic and flow-cytometric analyses

Abstract

Soil algae, which have received attention for their use in a novel bioassay to evaluate soil toxicity, expand the range of terrestrial test species. However, there is no information regarding the toxicity of nanomaterials to soil algae. Thus, we evaluated the effects of silver nanoparticles (0–50 mg AgNPs/kg dry weight soil) on the soil alga Chlamydomonas reinhardtii after six days, and assessed changes in biomass, photosynthetic activity, cellular morphology, membrane permeability, esterase activity, and oxidative stress. The parameters measured were markedly affected by AgNP-induced stress at 50 mg AgNPs/kg dry weight soil, where soil algal biomass, three measures of photosynthetic activity (area, reaction center per absorption flux, and reaction center per trapped energy flux), and esterase activity decreased. AgNPs also induced increases in both cell size and membrane permeability at 50 mg AgNPs/kg dry weight soil. In addition to the increase in cell size observed via microscopy, a mucilaginous sheath formed as a protective barrier against AgNPs. Thus, the toxicity of AgNPs can be effectively quantified based on the physiological, biochemical, and morphological responses of soil algae, where quantifying the level of toxicity of AgNPs to soil algae could prove to be a useful method in terrestrial ecotoxicology.

Effects of PEG-Coated Silver and Gold Nanoparticles on Spirulina platensis Biomass during Its Growth in a Closed System

“…The effects of AgNPs (0-50 mg AgNPs/kg dry weight soil) on the soil alga Chlamydomonas reinhardtii after a six-day exposure were evaluated. The photosynthetic activity of Chlamydomonas reinhardtii in AgNP-treated soils decreased at 50 mg AgNPs/kg treated soil in comparison to the control [42].…”

“…In the study of Hazeem et al [41], it was shown that AgNPs affected Chlorella vulgaris viability only at high AgNP concentrations (>100 mg/L). AgNPs inhibited the growth of Chlamydomonas reinhardtii at concentrations of 40 and 50 mg AgNPs/kg soil [42]. The highest toxicity effect on Dunaliella salina biomass was recorded at 1 mg/L of AgNPs at salinities (35,70, and 140 g/L) [43].…”

A study into the species sensitivity of green algae towards imidazolium-based ionic liquids using flow cytometry

“…This phenomenon usually occurs because of increased cell size or cell deformation (Franqueira et al, 2000;Franklin et al, 2001). However, an alternative explanation for this change in scattering intensity may be the formation of a mucilaginous sheath around the algal cells, as a protective barrier against the IL (Nam et al, 2018). When CIL <50 mg/L, the MFIs increased generally with CIL.…”

Nanoimpact in Plants: Lessons from the Transcriptome

“…Green Algae 6.1.1. Chlamydomonas Reinhardtii Unicellular, green algae have been widely used as sentinel species for ecotoxicological studies both in freshwater and soil ecosystems [43]. Thus, one of the first attempts to establish the potential impact of novel nanopollutans by using transcriptomics approaches was carried out in the model species C. reinhardtii [31].…”