ABSTRACT
Biofilm genesis by Pseudomonas and Staphylococcus sp is associated with biofouling in natural settings. D-Tryptophan (DTrp) inhibits bacterial biofilms and have been proposed for biofouling control applications. In this study, D-Trp significantlyinhibited Pseudomonas mendocina and Staphylococcus aureus cell attachment (biofilm formation) rates on polystyrene96-well microtiter plates in comparison with L-Tryptophan (L-Trp) and mixtures of D-/L-Tryptophan (D-/L-Trp). Theinhibitory effect was greater on P. mendocina, where the rate of cell adherence was declined to 8.7 9 105 cells/h from8.0 9 106 cells/h (control) in P. mendocina. In S. aureus it was declined to 4.2 9 107 cells/h from 9.2 9 107 cells/h(control) at 1 mM concentration. It hindered the intracellular communication and adherence in both the strains, as confirmed by SEM and real time PCR analysis. Addition of D-Trp to preformed biofilms also caused partial disassembly. Intraand interbacterial aggregation were decreased subsequently upon treatment with D-Trp. It repressed the genes involved incell–cell communication, which could be responsible for the diminished biofilm formation of the selected strains. HenceD-Tryptophan has proved to be an effective strategy to control biofilm and may support in the development of surfacecoating technologies.