Quercetin rapidly potentiates the biogenesis of nanoselenium via orchestrating key signaling pathways in Chlorella vulgaris

Microalgae are emerging as smart green cell factories for biochemical production and pollutant removal. However, few reports are available on potentiating the algal systems to synthesize selenium nanoparticles (SeNPs), particularly, molecular mechanisms underpinning this biotransformation are yet to be dissected. The Chlorella vulgaris is potentiated by fortifying quercetin (Qn) to facilitate the biotransformation of SeNPs. Quer-cetin rapidly enhanced the SeNPs formation within 72 hrs from 50 mu g/L Na2SeO3 by facilitating the intracellular electron transfer flow, with almost 97 % conversion of inorganic selenite to SeNPs. Electron microscopic analysis of the SeNPs with diameters ranging from 100 nm to 200 nm corroborated the biogenic ability of algal systems. Quercetin fortification obviated the physiological impairments in C. vulgaris induced by selenite in a dose -dependent manner; importantly, Qn-provision significantly enhanced the algal growth rate than the Se-treated cells. Moreover, Qn-treatment altered the fatty acid profile of the total lipids accumulated in C. vulgaris. Tran-scriptomic analysis showed that quercetin regulated the expression of critical metabolic candidates involved in the Se-assimilation pathway and ROS signal transduction. The data collectively demonstrate the potential green and eco-friendly strategy to reducing the toxic Se into SeNPs and elucidate the mechanistic role underpinning the quercetin-mediated green SeNP biogenesis.