Inhibition of indole production and attenuation of reactive oxygen species to reduce biofilm development

Bacterial biofilms provide survival mechanisms distinct from free-floating cells. An important mediator of biofilm formation in Escherichia coli ( E. coli ) is indole, which is formed by tryptophanase. In our study, E. coli biofilm formation was investigated in the context of removing indole production pathways, reducing indole production via a tryptophanase inhibitor (N-acetyl tryptophan), and by supplementing indole. We examined factors including indole production, the extent of biofilm generation, and reactive oxygen species (ROS) formation. Suppression of indole production by knockout of tryptophanase and by inhibitor-mediated reduction in tryptophanase activity both reduced biofilm formation in E. coli . In addition, there were indications that N-acetyl tryptophan could contribute to the anti-biofilm effect by affecting indole level and also the possibility of modulating ROS levels.