Interaction of silver nanoparticles with pure nitrifying bacteria
Zhihua Yuan1, Jiangwei Li, Li Cui
1Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Chemosphere
|September 19, 2012
Summary
Silver nanoparticles (AgNPs) inhibit ammonia oxidation in Nitrosomonas europaea by damaging cell walls and disrupting essential cellular functions. This size- and coating-dependent toxicity is linked to both dissolved silver and nanoparticle dispersity.
Area of Science:
- Environmental Microbiology
- Nanotechnology
- Biochemistry
Background:
- Nitrosomonas europaea is crucial for nitrification in aquatic ecosystems.
- Silver nanoparticles (AgNPs) are increasingly used, raising concerns about their environmental impact.
- Understanding AgNP toxicity to key microbial players like N. europaea is vital.
Purpose of the Study:
- To investigate the effects of AgNPs with varying sizes and coatings on N. europaea.
- To elucidate the mechanisms underlying AgNP-induced toxicity in N. europaea.
- To determine the role of AgNP aggregation and dissolved silver in toxicity.
Main Methods:
- Exposure of N. europaea to AgNPs (different sizes and coatings).
- Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) for microstructural analysis.
- Ammonia oxidation rate measurements.
- Surface-enhanced Raman scattering (SERS) for cell membrane integrity.
- Protein expression analysis.
Main Results:
- AgNPs formed aggregates in the presence of N. europaea, influenced by bacterial cells and electrolytes.
- Size- and coating-dependent inhibition of ammonia oxidation was observed.
- AgNPs caused cell wall damage, nucleoid disintegration, and cell membrane disruption.
- Inhibition was attributed to both released dissolved silver and AgNP dispersity.
- AgNPs affected protein functions related to biosynthesis, gene expression, energy production, and nitrification.
Conclusions:
- AgNPs exhibit significant toxicity to N. europaea, impacting key metabolic processes.
- The observed toxicity is a complex interplay of AgNP properties (size, coating, dispersity) and biological interactions.
- Findings highlight the need for further research in complex environmental matrices like wastewater.
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