Abstract
The increased use of the nanoparticles (NPs) on several processes is notorious. In contrast the ecotoxicological effects of NPs have been scarcely studied. The main current researches are related to the oxide metallic NPs. In the present work, fifty-six bacterial strains were isolated from soil, comprising 17 different OTUs distributed into 3 classes: Bacilli (36 strains), Flavobacteria (2 strains), and Gammaproteobacteria (18 strains). Copper oxide nanoparticles (CuONPs) were synthesized using a process of chemical precipitation. The obtained CuONPs have a spherical shape and primary size less than 17 nm. Twenty-one strains were used to evaluate the cytotoxicity of CuONPs and 11 of these strains showed high sensibility. Among those 11 strains, 4 (Brevibacillus laterosporusstrain CSS8,Chryseobacterium indoltheticumstrain CSA28, andPantoea ananatisstrains CSA34 and CSA35) were selected to determine the kind of damage produced. The CuONPs toxic effect was observed at expositions over 25 mg·L−1and the damage to cell membrane above 160 mg·L−1. The electron microscopy showed the formation of cavities, holes, membrane degradation, blebs, cellular collapse, and lysis. These toxic effects may probably be due to the ions interaction, the oxide-reduction reactions, and the generation of reactive species.
Highlights
The use of nanoparticles (NPs) has largely increased in the last years, the expected projection for the engineered nanomaterials production reaching more than 58,000 tons for 2012–2020 [1]
Among twenty-one strains tested, eleven showed no resistance to CuONPs, while the strains CSR19A, CSL10A, and CSMB13A exhibited the highest resistances (17, 22.5, and 25 mg⋅L−1, resp.). Besides their sensibility to CuONPs exposition test and the originality for their use as toxicity model to the studied NP, we considered their importance in the contribution in soil microbial community and biogeochemical cycles
Several pure culture studies have shown that the bacterial interaction with NPs may produce cytotoxicity in different parts of the cell, such as membrane disorganization, denaturation of thiol containing membrane proteins, DNA damage [70,71,72], and oxidation beyond reactive oxygen species (ROS) production [25]
Summary
The use of nanoparticles (NPs) has largely increased in the last years, the expected projection for the engineered nanomaterials production reaching more than 58,000 tons for 2012–2020 [1]. The waste generated by the NPs industry has been demonstrated to affect directly the environment, mainly soil ecosystems, followed by water and air ones [2,3,4,5,6]. The environmental effect of some nanomaterials such as carbon nanotubes, metal, oxides, and zero-valent metal NPs has been well studied [9], information about its interaction and damage on native bacterial communities is still scarce. Soil microbial communities are involved in several biogeochemical cycles such as carbon, nitrogen, sulfur, and phosphorus ones [9, 10]. It is known that the bactericidal efficiency of NPs depends on the microorganism type, for instance, copper
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