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Front. Microbiol. | doi: 10.3389/fmicb.2019.02709

Label-free proteomic approach to study the non-lethal effects of silver nanoparticles on a gut bacterium

 Francesca Cappitelli1*,  Guido Domingo2,  Federica Villa3, Candida Vannini2, Elisa Garuglieri3,  Elisabetta Onelli3 and Marcella Bracale4
  • 1Dipartimento di Scienze per gli Alimenti, la Nutrizione e l’Ambiente, University of Milan, Italy
  • 2Department of Biotechnology and Life Sciences, University of Insubria, Italy
  • 3University of Milan, Italy
  • 4University of Insubria, Italy

Among all the food-related nanoparticles consumed every day, silver nanoparticles (AgNPs) have become one of the most commonly utilized, because of their anti-microbial properties. Despite their common use, the effects of sub-lethal concentrations of AgNPs, especially on gut biofilms, have been poorly investigated. To address this issue, we investigated in vitro the proteomic response of a mono-species Escherichia coli gut biofilm to chronic and acute exposures in sub-lethal concentrations of AgNPs. We used a new gel- and label-free proteomic approach based on shotgun nanoflow liquid chromatography-tandem mass spectrometry (LC-MS/MS). This approach allows a quantification of the whole proteome at a dynamic range that is higher than the traditional proteomic investigation. To assess all different possible exposure scenarios, we compared the biofilm proteome of four treatments: i) untreated cells for the control treatment, ii) cells treated with 1 μg/mL AgNPs for 24 h for the acute treatment, iii) cells grown with 1 μg/mL AgNPs for 96 h for the chronic treatment, and iv) cells grown in the presence of 1 μg/mL AgNPs for 72 h and then further treated for 24 h with 10 μg/mL AgNPs for the chronic+acute treatment. Among the 1917 proteins identified, 212 were significantly differentially expressed proteins. Several pathways were altered including biofilm formation, bacterial adhesion, stress response to reactive oxygen species (ROS), and glucose utilization.

Keywords: label free proteomics, silver nanoparticles, Non-lethal effects, gut biofilm, Acute and chronic exposure

Received: 28 May 2019; Accepted: 08 Nov 2019.

Copyright: © 2019 Cappitelli, Domingo, Villa, Vannini, Garuglieri, Onelli and Bracale. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Francesca Cappitelli, University of Milan, Dipartimento di Scienze per gli Alimenti, la Nutrizione e l’Ambiente, Milan, 20133, Italy, francesca.cappitelli@unimi.it