Effect of different D-amino acids on biofilm formation of mixed microorganisms

Abstract

This study aimed to determine the effects of D-tyrosine, D-aspartic acid, D-tryptophan and D-leucine on biofilm formation of mixed microorganisms. Results showed that, in the attachment stage, D-amino acids caused significant reduction in adhesion efficiency of mixed microorganisms to the membrane surface. Moreover, D-amino acids have a promoting effect on the reversible adhesion of mixed microorganisms. The addition of D-amino acid generally inhibited the biofilm biomass, of which D-tyrosine has the best inhibition effect. With the effect of D-tyrosine, D-aspartic acid, D-tryptophan and D-leucine, the protein in extracellular polymeric substance (EPS) decreased by 8.21%, 7.65%, 3.51% and 11.31%, respectively. The carbohydrates in EPS decreased by 29.53%, 21.44%, 14.60% and 10.54%, respectively. The results of excitation-emission matrix spectra (EEMs) suggested that the structural properties of the tyrosine-like proteins, tryptophan-like protein and humic-like acid might have changed by the D-amino acids. HIGHLIGHTS Biofilm formation of microorganisms with 24 h D-amino acids exposure were discussed.; D-amino acids reduced adhesion efficiency and increased desorption efficiency.; The biofilm biomass decreased with the addition of D-amino acids.; D-amino acids inhibited the secretion of carbohydrates and protein in EPS.;

Keywords

• adhesion and desorption
• biofilm
• d-amino acids
• extracellular polymeric substance (eps)
• mixed microorganisms