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Silver nanoparticles temporarily retard NO 2 − production without significantly affecting N 2 O release by Nitrosomonas europaea
Author(s) -
Michels Camila,
Yang Yu,
Moreira Soares Hugo,
Alvarez Pedro J. J.
Publication year - 2015
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.3071
Subject(s) - nitrite reductase , nitrosomonas europaea , nitrite , ammonia monooxygenase , chemistry , silver nanoparticle , nitric oxide , nitrosomonas , environmental chemistry , nitrification , nuclear chemistry , microbiology and biotechnology , biology , nitrogen , nanoparticle , nitrate , organic chemistry , nanotechnology , materials science
Nitrifying bacteria are highly susceptible to silver nanoparticles (AgNPs). However, the effect of sublethal exposure to AgNPs after their release of nitrogenous compounds of environmental concern (e.g., the greenhouse gas nitrous oxide [N 2 O] and the common water pollutant nitrite [NO 2 −]) has not been systematically investigated. The present study reports the effect of AgNPs (and potentially released silver ions [Ag + ]) on NO 2 − and N 2 O production by Nitrosomonas europaea , and on the transcription of the associated genes. The release of NO 2 − was more negatively affected than the production of N 2 O. For example, exposure to AgNPs at 0.075 mg/L temporarily enhanced N 2 O production (by 12%) without affecting nitrite release, whereas higher AgNP concentrations (>0.25 mg/L) inhibited NO 2 − release (by >12%) but not N 2 O production. Transcriptomic analyses corroborated these trends; AgNPs at 0.075 mg/L increased the expression of the nitric oxide reductase gene ( norQ ) associated with N 2 O production (by 5.3‐fold to 12.8‐fold), whereas both 0.075 mg/L of Ag + and 0.75 mg/L of AgNPs down‐regulated the ammonia monooxygenase gene ( amoA2 ; by 0.08‐fold to 0.15‐fold and 0.32‐fold to 0.64‐fold, respectively), the nitrite reductase gene ( nirK ; by 0.01‐fold to 0.02‐fold and 0.22‐fold to 0.44‐fold, respectively), and norQ (by 0.11‐fold to 0.15‐fold and 0.32‐fold to 0.57‐fold, respectively). These results suggest that AgNP release to sewage treatment plants and land application of AgNP‐containing biosolids should be minimized because of their potential temporary stimulation of N 2 O release and interference with nitrification. Environ Toxicol Chem 2015;34:2231–2235. © 2015 SETAC