l-Tryptophan prevents Escherichia coli biofilm formation and triggers biofilm degradation

► Escherichia coli mutants with decreased tryptophan synthesis showed higher biofilm formation. ► E. coli mutants with increased tryptophan degradation showed higher biofilm formation. ► E. coli biofilm formation was prevented by l-tryptophan addition. ► E. coli matured biofilm was degraded by l-tryptophan addition.