D‐Amino acids inhibit initial bacterial Adhesion: Thermodynamic evidence

Abstract

Bacterial biofilms are structured communities of cells enclosed in a self-produced hydrated polymeric matrix that can adhere to inert or living surfaces. D-Amino acids were previously identified as self-produced compounds that mediate biofilm disassembly by causing the release of the protein component of the polymeric matrix. However, whether exogenous D-amino acids could inhibit initial bacterial adhesion is still unknown. Here, the effect of the exogenous amino acid D-tyrosine on initial bacterial adhesion was determined by combined use of chemical analysis, force spectroscopic measurement, and theoretical predictions. The surface thermodynamic theory demonstrated that the total interaction energy increased with more D-tyrosine, and the contribution of Lewis acid–base interactions relative to the change in the total interaction energy was much greater than the overall nonspecific interactions. Finally, atomic force microscopy analysis implied that the hydrogen bond numbers and adhesion forces decreased with the increase in D-tyrosine concentrations. D-Tyrosine contributed to the repulsive nature of the cell and ultimately led to the inhibition of bacterial adhesion. This study provides a new way to regulate biofilm formation by manipulating the contents of D-amino acids in natural or engineered systems.

Disturbance of the bacterial cell wall specifically interferes with biofilm formation

“…The destructive effect of non-canonical D-amino acids on biofilms is a well-known phenomenon, first demonstrated when D-amino acids were identified as selfproduced disassembling factors in aging B. subtilis biofilms (Kolodkin-Gal et al, 2010;Oppenheimer-Shaanan et al, 2013). Non-canonical D-amino acids have been shown independently to inhibit biofilm formation and trigger biofilm disassembly in different model organisms (Hochbaum et al, 2011;Yu et al, 2012;Sanchez et al, 2013;Li and Wang, 2014;Si et al, 2014;Xing et al, 2015), and at concentrations that did not interfere with planktonic growth. Importantly, it was reported that B. subtilis NCIB 3610 (as well as many other natural isolates; Daligault et al, 2014) is carrying a defective allele of the dtd gene, involved in removal of D-amino acids from tRNA.…”

Bacterial d -amino acids suppress sinonasal innate immunity through sweet taste receptors in solitary chemosensory cells

“…D-amino acids may inhibit adhesion of bacterial cells to one another (45, 46). However, other studies starkly conflict with these results and suggest D-amino acids at 1 mM do not inhibit biofilm growth in S. aureus , B. subtilis , or S. epidermidis (47).…”

Modeling Biofilms in Water Systems with New Variables: A Review

“…In certain external environmental conditions, planktonic cells attached to the substratum, which also refers to adhesion [29]. Two types of adhesion occur: reversible and irreversible adhesion.…”