CdO Nanoparticle Toxicity on Growth, Morphology, and Cell Division in Escherichia coli

This Article deals with the toxicological study of synthesized CdO nanoparticles (NPs) on Escherichia coli. Characterization of the CdO NPs was done by DLS, XRD, TEM, and AFM studies, and the average size of NPs was revealed as 22 +/- 3 nm. The NPs showed bactericidal activity against E. coli. When NPs were added at midlog phase of growth, complete growth inhibitory concentration was found as 40 mu g/mL. Bacterial cells changed morphological features to filamentous form with increasing CdO NPs exposure time, and thereafter resulted in filamentation-associated clumping. From AFM study, severe damage of the cell surface was found in CdO NPs-treated cells. CdO NPs were found to interfere with the expression level of two conserved cell division components, ftsZ and ftsQ, in E. coli at both transcriptional and translational levels. Interference of CdO NPs in proper septum formation without affecting the nucleoid segregation was also observed in confocal micrographs. The elevated intracellular oxidative stress due to CdO NPs exposure seems to be one of the reasons for the changes in cell morphology and expression of division proteins in E. coli.