title: Inhibition of an enriched culture of ammonia oxidizing bacteria by two different nanoparticles: Silver and magnetite.
abstract: Metal and metal oxide nanoparticles are getting attention over the past years. They can be used to several purposes, especially in commercial and medical applications. Undoubtedly, this lead to higher production and, consequently, increasing the risks of exposition, once they can be released into environment without a proper control. However, their impact over the bacteria present in wastewater treatment plants (WWTP), manly over nitrifying bacteria, which are the most susceptible to toxic compounds, are still not very well established. Herein it was investigated the impact of silver nanoparticles (AgNP) and magnetite nanoparticles (FeNP), separately, over an ammonia oxidizing bacteria (AOB), during short-term exposure tests and it was also verified their impact on bacterial surface. The concentrations assessed were from 0 to 30mgAgNPL-1and from 0 to 1000mgFeNPL-1. Results showed that AOB specific nitrite production rate reduced 90% when exposed to 30mgAgNPL-1, and in almost 71% in the presence of 1000mgFeNPL-1. The concentration necessary to reduce 50% of AOB activity was 10.75mgAgNPL-1and 483.01mgFeNPL-1highlighting that AgNP can be 45 times more toxic to AOB than FeNP. Both nanoparticles attached to bacterial surface, even in the lower concentration tested, hindering AOB activity due to changes in the membrane permeability. Once nanoparticles remain attached in the biological sludge, which is used as fertilizer to soil, they can affect not only WWTP performance but also hindering soil quality and the ecosystem balance.
authors.affiliation: Federal University of Santa Catarina, Department of Chemical and Food Engineering, 88034-001 Florianópolis, SC, Brazil. Electronic address: camilamichels@yahoo.com.br.
authors.forename: Camila
authors.initials: C
authors.lastname: Michels
authors.affiliation: Federal University of Santa Catarina, Department of Chemical and Food Engineering, 88034-001 Florianópolis, SC, Brazil. Electronic address: perazzoli.simone@gmail.com.
authors.forename: Simone
authors.initials: S
authors.lastname: Perazzoli
authors.affiliation: Federal University of Santa Catarina, Department of Chemical and Food Engineering, 88034-001 Florianópolis, SC, Brazil. Electronic address: hugo.moreira.soares@ufsc.br.
authors.forename: Hugo
authors.initials: H
authors.lastname: M Soares
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D052203:Ferrosoferric Oxide; D053768:Metal Nanoparticles; D009573:Nitrites / Q000378:metabolism; D010084:Oxidation-Reduction; D012722:Sewage; D012834:Silver; D012988:Soil Microbiology
chemical_list: D009573:Nitrites; D012722:Sewage; D012834:Silver; D000641:Ammonia; D052203:Ferrosoferric Oxide
keywords: Environmental pollution; Inhibition tests; Metallic nanoparticles; Nitrifying bacteria