Insights into the Ecotoxicity of Silver Nanoparticles Transferred from Escherichia coli to Caenorhabditis elegans.

Xun Luo,Yaning Yang,An Xu,Shaopeng Chen,Luzhi Li,Shengmin Xu,Lijun Wu

doi:10.1038/srep36465

Abstract

Previous studies have indicated that engineered nanomaterials can be transferred through the food chain. However, their potential ecotoxicity to the environment is not fully understood. Here, we systematically evaluated the physiological behavior and toxicity of polyvinylpyrrolidone (PVP)-coated silver nanoparticles (AgNPs) using a food chain model from Escherichia coli (E. coli) to Caenorhabditis elegans (C. elegans). Our results demonstrated that AgNPs accumulated in E. coli could be transferred to the C. elegans, and AgNPs were clearly distributed in the gut lumen, subcutaneous tissue and gonad. After being transferred to C. elegans through the food chain, the accumulated AgNPs caused serious toxicity to the higher trophic level (C. elegans), including effects on germ cell death, reproductive integrity and life span. Relative to larger particles (75 nm), small AgNPs (25 nm) more easily accumulated in the food chain and exhibited a stronger toxicity to the higher trophic level. More importantly, both the AgNPs that had accumulated in C. elegans through the food chain and the resulting impairment of germ cells could be transferred to the next generation, indicating that AgNP can cause genetic damage across generations. Our findings highlight that nanomaterials pose potential ecotoxicity to ecosystems via transport through the food chain.

Highlights

Silver nanoparticles (AgNPs) and related products have been widely used in medicine and in commercialized products for their antimicrobial property[1,2]
After incubation in the test medium (Luria Bertani, LB) for 12 h, transmission electron microscopy (TEM) images showed that the AgNPs had aggregated greatly and that the hydrodynamic diameter had changed to 100–1000 nm
We further investigated the toxicity of AgNPs and Ag+ ions on E. coli using the flow cytometric method, which indicated that the AgNPs-treated E. coli cells used in our trophic transfer studies were mostly alive at the time of feeding to C. elegans (Fig. S1c)

Summary

Introduction

Silver nanoparticles (AgNPs) and related products have been widely used in medicine and in commercialized products for their antimicrobial property[1,2]. Another study reported the trophic transfer and biomagnification of gold nanoparticles from tobacco plants to tobacco hornworms[15] These results demonstrate the potential trophic transfer of ENMs and raise the likelihood of human exposure through dietary uptake. C. elegans is a broadly distributed nematode species in soil ecosystems and plays a key role in nutrient cycling It has been widely employed as a test model in toxicology studies from the whole-animal level down to the single-cell level[10,19]. C. elegans has a translucent body that can be exploited to observe the distribution of AgNPs in the organ system It is an excellent food chain model to elucidate the potential ecotoxicological effects of AgNPs. Here, we systematically studied the ecotoxicity of AgNPs by following their transfer from Escherichia coli to C. elegans. Our findings illustrate the potential ecotoxicity of AgNPs that are released into the environment onto food webs

Methods

Results

Conclusion