Chromium oxide nano-particles induce stress in bacteria: probing cell viability.

In this study, viability of an environmentally relevant bacterium, Escherichia coli exposed to 0-100 microg/mL chromium oxide nanoparticles (Cr2O3, Nps) for 120 min in Luria Bertani broth was evaluated by Propidium monoazide (PMA) assisted Q-PCR and standard plate count (SPC) method. Viable count for E. coli grown in Cr2O3, Nps amended medium was more by PMA assisted Q-PCR than SPC. Thus, the observations made in this study suggest that the inclusion of PMA assisted Q-PCR for viability assessment in Nps toxicity studies will provide the real count for the viable cells comprising of both viable and viable but not culturable (VBNC) cells.