Selenium and tellurium-based nanoparticles as interfering factors in quorum sensing-regulated processes: violacein production and bacterial biofilm formation.

A cell-to-cell communication system called quorum sensing (QS) promotes the transcription of certain target genes in bacterial cells leading to the activation of different cellular processes, some of them related to bacterial biofilm formation. The formation of bacterial biofilms favours antibiotic resistance, which is nowadays a significant public-health problem. In this study, the effect of selenium (SeNPs) and tellurium (TeNPs) nanoparticles was examined in two bacterial processes mediated by QS: violacein production by Chromobacterium violaceum and biofilm formation by Pseudomonas aeruginosa. For this purpose, quantification of the pigment production in the presence of these nanoparticles was monitored using the C. violaceum strain. Additionally, a combination of different microscopical imaging techniques was applied to examine the changes in the 3D biofilm structure of P. aeruginosa, which were quantified through performing architectural metric calculations (substratum area, cell area coverage and biovolume). SeNPs produce an 80% inhibition in the violacein production by C. violaceum and a significant effect on the P. aeruginosa biofilm architecture (a reduction of 80% in the biovolume of the bacterial biofilm was obtained). TeNPs similarly affect violacein production and the P. aeruginosa biofilm structure but at lower concentration levels. The results obtained suggest an important disruption of the QS signalling system by SeNPs and TeNPs, supporting nanotechnology as a promising tool to fight against the emerging problem of bacterial resistance related to bacterial biofilm formation.