Abstract:In this study, the effect of a 405-nm light-emitting diode (LED) on the removal of the Staphylococcus aureus (S. aureus) biofilm formed on the surface of stainless steel was investigated. Firstly, the inactivation effect of 405-nm LED illumination on the viable cells in the S. aureus biofilm formed on stainless steel was determined. Then, the possible mechanisms underlying the biofilm clearance effects of LED were investigated through analyzing the resistance of S. aureus biofilm to disinfectants, chemical composition of the biofilm and the changes in the microstructure of biofilms after the 405-nm LED treatment. Results showed that the 405-nm LED treatment could significantly reduce the number of viable biofilm cells: The 4 h LED treatment at 4 ℃, 10 ℃ and 25 ℃ led to decreases in viable cells in the biofilm by 2.03 log CFU/cm2, 2.08 log CFU/cm2 and 3.00 log CFU/cm2, respectively, compared with the control group; the 405-nm LED treatment also decreased the tolerance of the treated biofilm cells to disinfectants, destroyed the integrity and three-dimensional structure of the biofilm's stereoscopic conformation, and reduced the contents of the main components of the biofilm (extracellular polysaccharides and extracellular proteins). The above research results indicated that the 405-nm LED illumination could effectively clear the S. aureus biofilm on the surface of stainless steel sheets, and has the potential to be further developed as a new biofilm removal method for the control of S. aureus biofilm contamination. Key words:
