Both biogenic and chemically synthesized metal sulfide nanoparticles induce oxidative stress and enhance lipid accumulation in Rhodococcus opacus.

Abstract

Metallic nanoparticles (NPs) find applications in many different industrial sectors. However, the fate of these NPs in the environment and their potential impact on organisms living in different ecosystems are not fully known. In this work, the individual effect of biogenic and chemically synthesized lead sulfide nanoparticles (PbSNPs) and cadmium sulfide nanoparticles (CdSNPs) on the activity of the oleaginous bacterium Rhodococcus opacus PD630 which belongs to an ecologically important genus Rhodococcus was investigated. A dose-dependent increase in PbSNPs and CdSNPs uptake by the bacterium was observed upto a maximum of 16.4 and 15.6mg/g cell, corresponding to 98% and 95% uptake. In the case of chemically synthesized NPs, the specific PbSNPs and CdSNPs uptake were slightly less [15.5 and 14.8mg/g cell], corresponding to 93.2% and 88.4% uptake. Both biogenic and chemically synthesized PbSNPs and CdSNPs did not affect the bacterial growth. On the other hand, the triacylglycerol (biodiesel) content in the bacterium increased from 30% to a maximum of 75% and 73% CDW due to oxidative stress induced by biogenic PbSNPs and CdSNPs. The results of induced oxidative stress by biogenic metal nanoparticle were similar to that induced by the chemically synthesized NPs.