Impact of silver nanoparticles on marine diatom Skeletonema costatum

Abstract

When silver nanoparticles (AgNPs) are used commercially at a large scale, they infiltrate the environment at a rapid pace. However, the impact of large quantities of AgNPs on aquatic ecosystems is still largely unknown. In aquatic ecosystems, the phytoplanktons have a vital ecological function and, therefore, the potential impact of AgNPs on the microalgae community has elicited substantial concern. Therefore, in this study, the impacts of AgNPs on a marine diatom, the Skeletonema costatum, are investigated, with a focus on their photosynthesis and associated mechanisms. Exposure to AgNPs at a concentration of 0.5 mg l À1 significantly induces excess intracellular reactive oxygen species (ROS, 122%) and reduces 28% of their cell viability. More importantly, exposure to AgNPs reduces the algal chlorophyll-a content. Scanning electron microscopy (SEM) was conducted, which revealed that AgNPs obstruct the light absorption of algae because they adhere to their surface. The maximum photochemical efficiency of photosystem II (Fv/Fm) demonstrates that exposure to AgNPs significantly inhibits the conversion of light energy into photosynthetic electron transport. Moreover, the genes of the photosystem II reaction center protein (D1) are significantly down-regulated (P < 0.05) upon exposure to 5 mg l À1 AgNPs. These results suggest that the physical adhesion and effects of shading of AgNPs on algae might affect their light energy delivery system and damage the crucial protein function of PSII. The photosynthesis inhibition effect of AgNPs is largely different from Ag + . This study shows that AgNPs at higher concentrations might have serious consequences for the succession of the phytoplankton communities and aquatic ecosystem equilibrium.

Effect of Silver Nanoparticles on Tropical Freshwater and Marine Microalgae

“…In aquatic environment, green algae and diatom are not only the primary producers for higher tropic levels but also play an important role for the normal functioning of aquatic ecosystems [10]. Numerous studies have demonstrated that NPs generated adverse effects on freshwater and marine microalgae species [3,[24][25][26].…”

“…In ecological ecosystems, the microalgae are primary producers and play a vital role in the food chains. us, the bad effects of pollutants on microalgae species may break the balance of whole ecosystems [10]. e toxic effect and behavior of nanomaterial in the ecosystems on microalgae have been recently reviewed [3,11].…”

“…Decrease in chlorophyll content, viable algal cells, increased reactive oxygen species (ROS) formation, and lipid peroxidation in the freshwater microalga Chlorella vulgaris and marine microalga Dunaliella tertiolecta were observed after exposure to AgNPs for 24 h [16]. Huang et al [10] reported that AgNPs at a concentration of 0.5 mg/L caused both significantly induced excess intracellular ROS and decreased cell viability in the marine diatom Skeletonema costatum.…”

Characterization and Impact of Silver nanoparticles on cell growth, lipid, carbohydrate and fatty acids of Chlorella vulgaris and Dictyochloropsis splendida

“…The enhancement of biotic generation of antioxidant enzymes has been reported in Chattonella marina as a defence mechanism against the adverse effect of AgNPs on PS II, which may involve inhibition of electron transport activity and alteration of oxygen evolution [65] ; [20] ; [17]. Table (3 splendida showed lower biomass growth and lipid productivity, yield and content than the C. vulgaris.…”

“…The use of trace or low nanoparticle concentrations has reportedly induced stimulation of algal biomass and pigment content with enhanced lipid production [11][12][13][14][15][16]. The effects of AgNPs on diatom Skeletonema costatum [17], Thalassiosira pseudonana and Cyanobacterium synechococcus sp. [18] and the eukaryotic green algae [6] have been reported.…”