Title : Multi-threaded effects of metal nanoparticles on the structure and selected molecular processes in model Escherichia coli, Bacillus cereus and Staphylococcus epidermidis strains
Abstract:
The extensive use of nanomaterials in consumer and industrial products is driven by their unique physicochemical and biological characteristics. Among these, inorganic nanomaterials — especially metallic nanoparticles (NPs) and their oxides (MONPs, metal-oxide nanoparticles) — have garnered significant attention over the past decade. Engineered new nano-products have become more prevalent in diverse fields, and concerns arise about their uncontrolled release into the environment, potentially exposing living organisms, including microorganisms, to toxic and undesirable effects.
Nanoparticles are known for their distinct antimicrobial properties and ability to disrupt various cellular processes, especially the antioxidant defence system and cell surface integrity. However, limited data exists on how NPs influence the expression of genes encoding these antioxidants and the function of related molecular proteins. Therefore, ongoing research on bacterial antioxidant defense systems and cell membrane structure is essential and highly valuable in answering many unanswered questions and explaining in detail the mechanisms involved in cell response to NPS at the molecular level.
Therefore, this study aimed to explore the diverse effects of commercial nanoparticles Ag-NPs, Cu-NPs, ZnO-NPs and TiO?-NPs on the cellular antioxidant defence system as well as the structure and function of cell membranes in model bacterial species, including Escherichia coli, Bacillus cereus, and Staphylococcus epidermidis.
The results demonstrated the impact of NPs on microorganisms, affecting their survivability and functionality. All tested NPs altered the gene expression of chosen proteins and the functioning of antioxidant enzymes. Most NPs up-regulated bacterial oxidative stress gene expression correlated with increased antioxidant activity. The observed changes depended exclusively on the type of NPs and studied microorganisms. The most significant differences between transcriptional and catalytic profiles were established for peroxidase and catalase-like proteins. The fatty acid profiles were unique for each strain and indicated substantial changes in the percentages of hydroxyl, cyclopropane, branched, and unsaturated fatty acids. All NPs were characterised by solid affinity and diversified distribution on the surface of bacterial cells, often leading to changes in their morphology and severe surface damage. Generally, changes in the structure and properties of bacterial cell envelopes depended on the type of NPs and were species-specific.
