The response of Escherichia coli biofilm to salicylic acid

Abstract

In this research, salicylic acid is proposed as an alternative biocide-free agent suitable for a preventive or integrative anti-biofilm approach. Salicylic acid has been proved to: (1) reduce bacterial adhesion up to 68.1 ± 5.6%; (2) affect biofilm structural development, reducing viable biomass by 97.0 ± 0.7% and extracellular proteins and polysaccharides by 83.9 ± 2.5% and 49.5 ± 5.5% respectively; and (3) promote biofilm detachment 3.4 ± 0.6-fold. Moreover, salicylic acid treated biofilm showed an increased amount of intracellular (2.3 ± 0.2-fold) and extracellular (2.1 ± 0.3-fold) reactive oxygen species, and resulted in increased production of the quorum sensing signal indole (7.6 ± 1.4-fold). For the first time, experiments revealed that salicylic acid interacts with proteins that play a role in quorum sensing, reactive oxygen species accumulation, motility, extracellular polymeric matrix components, transport and metabolism.

Low density polyethylene functionalized with antibiofilm compounds inhibits Escherichia coli cell adhesion

“…It has been found that ZA targets key step involved in E. coli biofilm formation by modulating the threshold level of the autoinducer‐2 signal and inducing a hypermotile phenotype unable to firmly adhere on surfaces . Conversely, SA anti‐biofilm action involves multiple complex mechanisms affecting cells adhesion, extracellular matrix production, the quorum sensing indole balance and bacterial motility also making biofilm more prone to be dethatched from the surface . It has been speculated that both molecules exploit their anti‐biofilm performances by a ROS‐based mechanism that modulates the activity of some proteins resulting in a decrease of biofilm formation.…”

“…Recently, it has been found that E. coli proteins targeted by ZA and SA are widespread with a high percentage of identity in a wide range of microorganisms, included several E. coli pathogenic stains and bacteria involved in serious disease. Thus, it is possible that LDPE‐CA and LDPE‐ZA could exert their activity also against other bacterial strains.…”

“…42 Conversely, SA anti-biofilm action involves multiple complex mechanisms affecting cells adhesion, extracellular matrix production, the quorum sensing indole balance and bacterial motility also making biofilm more prone to be dethatched from the surface. 23,[43][44][45] It has been speculated that both molecules exploit their anti-biofilm performances by a ROS-based mechanism that modulates the activity of some proteins resulting in a decrease of biofilm formation. Indeed, cells use ROS as a signal or cue to adapt to a changing environment.…”

“…Their biological investigation led us to the identification of the commercially available p ‐aminosalicylic acid as a suitable antibiofilm compound used as reference in the grafting process. Moreover, among the proteins targeted by salicylic acid (WrbA, MenI), we have recently identified a tryptophanase involved in indole synthesis, TnaA . This article is focused on the functionalization of a polymeric support with p ‐aminocinnamic acid and p ‐aminosalicylic acid in order to obtain novel materials able to hinder E. coli biofilm formation.…”

“…Moreover, among the proteins targeted by salicylic acid (WrbA, MenI), we have recently identified a tryptophanase involved in indole synthesis, TnaA. 23 This article is focused on the functionalization of a polymeric support with p-aminocinnamic acid and p-aminosalicylic acid in order to obtain novel materials able to hinder E. coli biofilm formation. In contrast to a LDPE film, a 1.6 mm thick coupon with a polymeric surface was prepared for the immobilization of biologically active molecules by a multi-step process.…”