The use of engineered nanoparticles (ENPs) has risen due to the wide range of applications in the field of electronics, medicine, chemistry and biology. However, the impact of ENPs on biological systems is still not well understood. The aim of this research was to determine the effects of zinc oxide (ZnO) and cerium oxide (CeO2) NPs towards the gram-negative nitrogen fixing bacterium Sinorhizobium meliloti (Rm 1021). Bactericidal effects of both the NPs were determined by Minimum Inhibitory Concentration (MIC), Disk Diffusion tests (diameter of inhibition zone i;e DIZ) and by dynamic growth measurements with Uv-Vis spectroscopy. Furthermore, Scanning transmission electron microscope (STEM) images helped to reveal the location of NPs on bacterial surface and suggested some structural changes along with the surface attachments. We reported the accumulation of CeO2 and ZnO NPs into the periplasmic space of the bacteria. This was further investigated by the structural modification of extracted extracellular polysacharhides (EPS) present in bacterial cell envelope. The FT-IR spectra showed changes in protein and polysaccharide structure of bacterial cell surface upon application of NPs. We also reported the effect of CeO2 NPs on S. meliloti is bacteriostatic whereas ZnO NPs act as bactericidal.

Comparative toxicity assessment of CeO<sub>2</sub> and ZnO nanoparticles towards nitrogen fixing gram negative species <i>Sinorhizobium meliloti</i>

244th National Meeting (2012)

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Comparative toxicity assessment of CeO2 and ZnO nanoparticles towards nitrogen fixing gram negative species Sinorhizobium meliloti

Comparative toxicity assessment of CeO₂ and ZnO nanoparticles towards nitrogen fixing gram negative species Sinorhizobium meliloti