The Effects of D-Amino Acids on Staphylococcus Aureus SA113 Biofilm Formation
Biofilms play a major role in the development of drug-resistant, persistent bacterial infections. D-amino acids have been proposed as biofilm inhibitors that prevent biofilm formation by incorporating into the peptidoglycan. We investigated this mechanism of inhibition using SA113, a Staphylococcus aureus clinical isolate that exhibits strong biofilm formation. The dispersive and inhibitory effects of D-tyrosine, D-phenylalanine, and D-proline were measured with a crystal violet biofilm assay. The addition of D-amino acids during or after biofilm formation did not disperse the biofilm or inhibit its formation. To study the proposed D-amino acid incorporation into peptidoglycan, SA113 cells were treated with mutanolysin and then analyzed with liquid chromatography-mass spectrometry (LC-MS). Our initial LC-MS analysis of SA113 grown in the presence and absence of D-amino acids suggested that peptidoglycan composition was not affected by the addition of D-amino acids.