Biogenic Silver for Disinfection of Water Contaminated with Viruses

Abstract

The presence of enteric viruses in drinking water is a potential health risk. Growing interest has arisen in nanometals for water disinfection, in particular the use of silver-based nanotechnology. In this study, Lactobacillus fermentum served as a reducing agent and bacterial carrier matrix for zerovalent silver nanoparticles, referred to as biogenic Ag ⁰ . The antiviral action of biogenic Ag ⁰ was examined in water spiked with an Enterobacter aerogenes -infecting bacteriophage (UZ1). Addition of 5.4 mg liter ⁻¹ biogenic Ag ⁰ caused a 4.0-log decrease of the phage after 1 h, whereas the use of chemically produced silver nanoparticles ( n Ag ⁰ ) showed no inactivation within the same time frame. A control experiment with 5.4 mg liter ⁻¹ ionic Ag ⁺ resulted in a similar inactivation after 5 h only. The antiviral properties of biogenic Ag ⁰ were also demonstrated on the murine norovirus 1 (MNV-1), a model organism for human noroviruses. Biogenic Ag ⁰ was applied to an electropositive cartridge filter (NanoCeram) to evaluate its capacity for continuous disinfection. Addition of 31.25 mg biogenic Ag ⁰ m ⁻² on the filter (135 mg biogenic Ag ⁰ kg ⁻¹ filter medium) caused a 3.8-log decline of the virus. In contrast, only a 1.5-log decrease could be obtained with the original filter. This is the first report to demonstrate the antiviral efficacy of extracellular biogenic Ag ⁰ and its promising opportunities for continuous water disinfection.