Chronic Exposure Effects of Silver Nanoparticles on Stream Microbial Decomposer Communities and Ecosystem Functions

Abstract

With the accelerated use of silver nanoparticles (AgNP) in commercial products, streams will increasingly serve as recipients of, and repositories for, AgNP. This raises concerns about the potential toxicity of these nanomaterials in the environment. Here we aimed to assess the impacts of chronic AgNP exposure on the metabolic activities and community structure of fungal and bacterial plant litter decomposers as central players in stream ecosystems. Minimal variation in the size and surface charge of AgNP indicated that nanoparticles were rather stable during the experiment. Five days of exposure to 0.05 and 0.5 μM AgNP in microcosms shifted bacterial community structure but had no effect on a suite of microbial metabolic activities, despite silver accumulation in the decomposing leaf litter. After 25 days, however, a broad range of microbial endpoints, as well as rates of litter decomposition, were strongly affected. Declines matched with the total silver concentration in the leaves and were accompanied by changes in fungal and bacterial community structure. These results highlight a distinct sensitivity of litter-associated microbial communities in streams to chronic AgNP exposure, with effects on both microbial functions and community structure resulting in notable ecosystem consequences through impacts on litter decomposition and further biogeochemical processes.

Significance of sunlight for organic matter degradation in aquatic systems

“…phenolic content) also seems to negatively affect microbial resource niche breadth. The observed negative effects of sunlight on OM-associated microbial communities also likely reduce overall microbial respiratory activity and microbial biomass production, which itself may already retard microbiallymediated OM degradation (Tlili et al 2017) and growth of invertebrates that consume microbially-conditioned OM (Zhai et al 2018).…”

An Integrated In Vitro–In Silico Approach for Silver Nanoparticle Dosimetry in Cell Cultures

“…It can be coated on biomedical devices 9 , used in medical contexts for personal health care 16 or biological applications 35 , and adapted for food products such as kitchen tools, storage containers and cutting boards 30 . However, despite the growing use of silver nanoparticles (Ag NPs) in the last decade 1,7,25,43 , potential human and environmental hazards resulting from exposure to Ag NPs continue to be the subject of attention 37,52 owing to their welldocumented toxicity both in vivo and in vitro.…”

Light Pollution Changes the Toxicological Effects of Cadmium on Microbial Community Structure and Function Associated with Leaf Litter Decomposition

“…Plant litter decomposition plays an important role and provides key ecosystem services through the cycling of organic matter in the freshwater ecosystem governed by microbial decomposers [1]. Among microbial decomposers, fungi have proven to dominate the leaf litter decomposition and are more sensitive to contaminants than bacteria, providing a suitable model to assess contaminant effects on complex ecological systems [2,3].…”