TY - JOUR
T1 - Comparative toxicity assessment of CeO2 and ZnO nanoparticles towards Sinorhizobium meliloti, a symbiotic alfalfa associated bacterium
T2 - Use of advanced microscopic and spectroscopic techniques
AU - Bandyopadhyay, Susmita
AU - Peralta-Videa, Jose R.
AU - Plascencia-Villa, Germán
AU - José-Yacamán, Miguel
AU - Gardea-Torresdey, Jorge L.
N1 - Funding Information:
This material is based upon work supported by the National Science Foundation and the Environmental Protection Agency under Cooperative Agreement Number DBI-0830117. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or the Environmental Protection Agency. This work has not been subjected to EPA review and no official endorsement should be inferred. The authors also acknowledge the USDA Grant Numbers 2008-38422-19138 and 2011-38422-30835 the NSF Grant # CHE-0840525 and the Facilities of Kleberg Advanced Microscopy Center and RCMI NIH Nanotechnology and Human Health Core at UTSA. J.L. Gardea-Torresdey acknowledges the Dudley family for the Endowed Research Professorship in Chemistry. The authors also acknowledge Dr. Guillermo Carrillo-Castaneda from Postgraduate College of Chapingo, Mexico who kindly supplied the bacterial cells and Dr. Jose Nunez for his help in the IR studies.
PY - 2012/11/30
Y1 - 2012/11/30
N2 - Cerium oxide (CeO2) and zinc oxide (ZnO) nanoparticles (NPs) are extensively used in a variety of instruments and consumer goods. These NPs are of great concern because of potential toxicity towards human health and the environment. The present work aimed to assess the toxic effects of 10nm CeO2 and ZnO NPs towards the nitrogen fixing bacterium Sinorhizobium meliloti. Toxicological parameters evaluated included UV/Vis measurement of minimum inhibitory concentration, disk diffusion tests, and dynamic growth. Ultra high-resolution scanning transmission electron microscopy (STEM) and infrared spectroscopy (FTIR) were utilized to determine the spatial distribution of NPs and macromolecule changes in bacterial cells, respectively. Results indicate that ZnO NPs were more toxic than CeO2 NPs in terms of inhibition of dynamic growth and viable cells counts. STEM images revealed that CeO2 and ZnO NPs were found on bacterial cell surfaces and ZnO NPs were internalized into the periplasmic space of the cells. FTIR spectra showed changes in protein and polysaccharide structures of extra cellular polymeric substances present in bacterial cell walls treated with both NPs. The growth data showed that CeO2 NPs have a bacteriostatic effect, whereas ZnO NPs is bactericidal to S. meliloti. Overall, ZnO NPs were found to be more toxic than CeO2 NPs.
AB - Cerium oxide (CeO2) and zinc oxide (ZnO) nanoparticles (NPs) are extensively used in a variety of instruments and consumer goods. These NPs are of great concern because of potential toxicity towards human health and the environment. The present work aimed to assess the toxic effects of 10nm CeO2 and ZnO NPs towards the nitrogen fixing bacterium Sinorhizobium meliloti. Toxicological parameters evaluated included UV/Vis measurement of minimum inhibitory concentration, disk diffusion tests, and dynamic growth. Ultra high-resolution scanning transmission electron microscopy (STEM) and infrared spectroscopy (FTIR) were utilized to determine the spatial distribution of NPs and macromolecule changes in bacterial cells, respectively. Results indicate that ZnO NPs were more toxic than CeO2 NPs in terms of inhibition of dynamic growth and viable cells counts. STEM images revealed that CeO2 and ZnO NPs were found on bacterial cell surfaces and ZnO NPs were internalized into the periplasmic space of the cells. FTIR spectra showed changes in protein and polysaccharide structures of extra cellular polymeric substances present in bacterial cell walls treated with both NPs. The growth data showed that CeO2 NPs have a bacteriostatic effect, whereas ZnO NPs is bactericidal to S. meliloti. Overall, ZnO NPs were found to be more toxic than CeO2 NPs.
KW - Bactericidal
KW - Bacteriostatic
KW - CeO
KW - Extracellular polymeric substances
KW - Sinorhizobium meliloti
KW - ZnO
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U2 - 10.1016/j.jhazmat.2012.09.056
DO - 10.1016/j.jhazmat.2012.09.056
M3 - Article
C2 - 23083939
AN - SCOPUS:84868470769
SN - 0304-3894
VL - 241-242
SP - 379
EP - 386
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
ER -