title: An investigation into the effects of silver nanoparticles on natural microbial communities in two freshwater sediments.
abstract: The expanding production and usage of commercial silver nanoparticles (AgNPs) will inevitably increase their environmental release, with sediments as a substantial sink. However, little knowledge is available about the potential impacts of AgNPs on freshwater sediment microbial communities, as well as the interactions between microbial communities and biogeochemical factors in AgNPs polluted sediment. To address these issues, two different sediments: a eutrophic freshwater sediment and an oligotrophic freshwater sediment, were exposed to 1 mg/g of either AgNO3, uncoated AgNPs (35-nm and 75-nm), or polyvinylpyrrolidone coated AgNPs (PVP-AgNPs) (30-50 nm) for 45 days. High-throughput sequencing of 16S ribosomal ribonucleic acid (16S rRNA) genes using the Illumina MiSeq platform was conducted to evaluate the effects of Ag addition on bacterial community composition. Moreover, sediment microbial biomass and activity were assessed by counting cultivable bacterial number and determining enzyme activities. During the 45-day exposure, compared with no amendment control, some treatments had resulted in significant changes and alterations of sediment biomass or bacterial enzyme activities shortly. While the microbial components at phylum level were rarely affected by AgNPs addition, and as confirmed by the statistical analysis with two-factor analysis of similarities (ANOSIM), there were no significant differences on bacterial community structure across the amended treatments. Redundancy analysis further demonstrated that chemical parameters acid-volatile sulfide (AVS) and simultaneously extracted silver (SE-Ag) in sediment significantly structured the overall bacterial community in sediments spiked with various silver species. In summary, these findings suggested that the ecotoxicity of AgNPs may be attenuated by the transformation under complex environmental conditions and the self-adaption of sediment microbial communities.
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Shaopan
authors.initials: S
authors.lastname: Bao
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Han
authors.initials: H
authors.lastname: Wang
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Weicheng
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Zhicai
authors.initials: Z
authors.lastname: Xie
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China. Electronic address: fangt@ihb.ac.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Fang
mesh_terms: D001419:Bacteria / Q000187:drug effects* / Q000235:genetics; D018533:Biomass; D005618:Fresh Water / Q000382:microbiology*; D019015:Geologic Sediments / Q000382:microbiology*; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D059013:Microbial Consortia / Q000187:drug effects / Q000235:genetics; D011205:Povidone / Q000737:chemistry; D012336:RNA, Ribosomal, 16S; D012834:Silver / Q000633:toxicity*; D013440:Sulfides; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D012336:RNA, Ribosomal, 16S; D013440:Sulfides; D014874:Water Pollutants, Chemical; D012834:Silver; D011205:Povidone
keywords: Bacterial community structure; Enzyme activities; Freshwater sediment; Silver nanoparticles