How Bacteria Change after Exposure to Silver Nanoformulations: Analysis of the Genome and Outer Membrane Proteome

Abstract

Objective: the main purpose of this work was to compare the genetic and phenotypic changes of E. coli treated with silver nanoformulations (E. coli BW25113 wt, E. coli BW25113 AgR, E. coli J53, E. coli ATCC 11229 wt, E. coli ATCC 11229 var. S2 and E. coli ATCC 11229 var. S7). Silver, as the metal with promising antibacterial properties, is currently widely used in medicine and the biomedical industry, in both ionic and nanoparticles forms. Silver nanoformulations are usually considered as one type of antibacterial agent, but their physical and chemical properties determine the way of interactions with the bacterial cell, the mode of action, and the bacterial cell response to silver. Methods: the changes in the bacterial genome, resulting from the treatment of bacteria with various silver nanoformulations, were verified by analyzing of genes (selected with mutfunc) and their conservative and non-conservative mutations selected with BLOSUM62. The phenotype was verified using an outer membrane proteome analysis (OMP isolation, 2-DE electrophoresis, and MS protein identification). Results: the variety of genetic and phenotypic changes in E. coli strains depends on the type of silver used for bacteria treatment. The most changes were identified in E. coli ATCC 11229 treated with silver nanoformulation signed as S2 (E. coli ATCC 11229 var. S2). We pinpointed 39 genes encoding proteins located in the outer membrane, 40 genes of their regulators, and 22 genes related to other outer membrane structures, such as flagellum, fimbria, lipopolysaccharide (LPS), or exopolysaccharide in this strain. Optical density of OmpC protein in E. coli electropherograms decreased after exposure to silver nanoformulation S7 (noticed in E. coli ATCC 11229 var. S7), and increased after treatment with the other silver nanoformulations (SNF) marked as S2 (noticed in E. coli ATCC 11229 var. S2). Increase of FliC protein optical density was identified in turn after Ag+ treatment (noticed in E.coli AgR). Conclusion: the results show that silver nanoformulations (SNF) exerts a selective pressure on bacteria causing both conservative and non-conservative mutations. The proteomic approach revealed that the levels of some proteins have changed after treatment with appropriate SNF.

Anti-Bacterial Mechanism for Metallic Ag+, Cu2+, Zn2+ Ions-Induced Bactertiolysis on Disruptive OM Lpp and PGN Inhibitive Elongations Against S. aureus and E. coli

“…Silver inhibits outer membrane proteome (OMP) that The molecular mechanism of the antibacterial activity of silver and molecular changes in bacterial cells strongly depend on the physical and chemical properties of the tested silver nanoformulation form (SNF) [24]. A silver-binding peptide, AgBP2, was identified from a combinatorial display library and fused to the C terminus of the E. coli maltose-binding protein (MBP) to yield a silver-binding protein exhibiting nanomolar affinity for the metal [25].…”

Effect of surface treatment and shear flow on biofilm formation over materials employed in space water storage and distribution systems

“…Regarding the preservation of water, NASA intends to utilize biocidal silver in order to ensure the quality of potable water and prevent the harmful effects of microorganisms (Petala et al, 2017). The antimicrobial potential of silver is already well-known including deactivation of macromolecules such as DNA, RNA and proteins, cell membrane disruption and reactive oxygen species (ROS) generation (Kędziora et al, 2021). However, according to ESA and NASA documents (Rebeyre, 2012;Li et al, 2018;Li et al, 2019;Muirhead et al, 2020) as well the studies of our research group (Petala et al, 2017;Mintsouli et al, 2018), silver is depleted from water when it is in contact with metallic surfaces due to deposition phenomena.…”