Pedosphere 27(3): 482--490, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Effects of silver nanoparticles on soil microbial communities and bacterial nitrification in suburban vegetable soils |
WANG Juan, SHU Kunhui, ZHANG Li,SI Youbin |
| School of Resources and Environment, Anhui Agricultural University, Hefei 230036 (China) |
| ABSTRACT |
| Silver nanoparticles (AgNPs) are widely used antimicrobial compounds; however, they may pose a threat to non-targeted bacteria in the environment. In this study high-throughput sequencing was used to investigate the effects of different concentrations of AgNPs (10, 50, and 100 mg kg-1) on soil microbial community structure during short-term (7 d) exposure. The amounts of Acidobacte-ria, Actinobacteria, Cyanobacteria, and Nitrospirae significantly decreased with increasing AgNP concentration; meanwhile, several other phyla ( e.g., Proteobacteria and Planctomycetes) increased and dominated. Nitrosomonas europaea, a well-characterized ammonia-oxidizing bacterium, was used to study the sensitivity of bacteria to AgNPs and ionic silver (Ag+).Flow cytometry was used to monitor the toxicity of low (1 mg L-1), middle (10 mg L-1), and high concentrations (20 mg L-1) of AgNPs, as well as Ag+ (1 mg L-1) released into the medium from 20 mg L-1 concentration of AgNPs, towards N. europaea.After 12 h of exposure, the survival rate of N. europaea treated with 1 mg L-1 Ag+ was significantly lower than those treated with low (1 mg L-1) and middle concentrations (10 mg L-1) of AgNPs, but the survival rate in the treatment with high concentration (20 mg L-1) of AgNPs was much lower. Additionally, necrosis rates were higher in the treatment with 20 mg L-1 AgNPs. Electron microscopy showed that Ag+ caused serious damage to the cell wall of N. europaea, disintegrated the nucleoids, and condensed next to the cell membrane; however, dissolved Ag+ is only one of the antibacterial mechanisms of AgNPs. |
| Key Words: ammonia-oxidizing bacterium, cell necrosis, cytotoxicity, silver ions, survival rate |
| Citation: Wang J, Shu K H, Zhang L, Si Y B. 2017.Effects of silver nanoparticles on soil microbial communities and bacterial nitrification in suburban vegetable soils. Pedosphere. 27(3): 482--490. |
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