Bacterial Metabolites and Particle Size Determine Cerium Oxide Nanomaterial Biotransformation

Abstract

Soil is a major receptor of manufactured nanomaterials (NMs) following unintentional releases or intentional uses. Ceria NMs have been shown to undergo biotransformation in plant and soil organisms with a partial Ce(IV) reduction into Ce(III), but the influence of environmentally widespread soil bacteria is poorly understood. We used high-energy resolution fluorescencedetected X-ray absorption spectroscopy (HERFD-XAS) with an unprecedented detection limit to assess Ce speciation in a model soil bacterium (Pseudomonas brassicacearum) exposed to CeO 2 NMs of different sizes and shapes. The findings revealed that the CeO 2 NM's size drives the biotransformation process. No biotransformation was observed for the 31 nm CeO 2 NMs, contrary to 7 and 4 nm CeO 2 NMs, with a Ce reduction of 64 ± 14% and 70 ± 15%, respectively. This major reduction appeared quickly, from the early exponential bacterial growth phase. Environmentally relevant organic acid metabolites secreted by Pseudomonas, especially in the rhizosphere, were investigated. The 2keto-gluconic and citric acid metabolites alone were able to induce a significant reduction in 4 nm CeO 2 NMs. The high biotransformation measured for <7 nm NMs would affect the fate of Ce in the soil and biota.

Cerium oxide nanomaterials improve cucumber flowering, fruit yield and quality: the rhizosphere effect

“…Upon entering soil, CeO 2 NMs interact directly or indirectly with soil microorganisms, thereby affecting their metabolism. 35 It has been found that CeO 2 NMs underwent biotransformation in a microbial environment. 35 The electron extraction of Ce 4+ reduced to Ce 3+ can be used in the electron transport chain of cell energy production, thus changing the extracellular polymer of cells.…”

“…35 It has been found that CeO 2 NMs underwent biotransformation in a microbial environment. 35 The electron extraction of Ce 4+ reduced to Ce 3+ can be used in the electron transport chain of cell energy production, thus changing the extracellular polymer of cells. 36 The extracellular and intracellular metabolites secreted by soil organisms are components of the soil metabolite pool.…”

Advances in Nanodynamic Therapy for Cancer Treatment

“…However, the metabolism and excretion mechanisms of nanomedicines differ markedly from those of traditional drugs, potentially leading to accumulation within organisms and consequent long-term toxicity issues [123]. Furthermore, the size and surface characteristics of nanoparticles may influence their ability to navigate through hepatic, renal, or other excretory pathways, affecting not only the drug clearance rate but also the overall safety and efficacy of the therapeutic regimen [124]. the metabolism and excretion mechanisms of nanomedicines differ markedly from those of traditional drugs, potentially leading to accumulation within organisms and consequent long-term toxicity issues [123].…”

“…traditional drugs, potentially leading to accumulation within organisms and consequent long-term toxicity issues [123]. Furthermore, the size and surface characteristics of nanoparticles may influence their ability to navigate through hepatic, renal, or other excretory pathways, affecting not only the drug clearance rate but also the overall safety and efficacy of the therapeutic regimen [124]. Cisplatin Cl2H6N2Pt [114] In the domain of tumor therapy, nanomedicines predominantly operate through two major mechanisms: thermodynamics [125] and kinetics [126].…”

Rhizosphere regulation with cerium oxide nanomaterials promoted carrot taproot thickening

“…To date, many studies have demonstrated that NMs can regulate the composition and relative abundance of root exudates and the composition of rhizosphere microbial communities, thereby improving plant health. [13][14][15] However, most studies focused on plants with edible parts on the ground, and how NMs-mediated rhizosphere regulation affects the growth, development and productivity of rhizome crops remains largely unknown.…”