Inhibition and eradication of Salmonella Typhimurium biofilm using P22 bacteriophage, EDTA and nisin.

P22 phage >105 PFU ml-1 could be used to inhibit Salmonella Typhimurium biofilm formation by 55-80%. Concentrations of EDTA >1.25 mM and concentrations of nisin >1,200 µg ml-1 were also highly effective in reducing S. Typhimurium biofilm formation (≥96% and ≥95% reductions were observed, respectively). A synergistic effect was observed when EDTA and nisin were combined whereas P22 phage in combination with nisin had no synergistic impact on biofilm formation. Triple combination of P22 phage, EDTA and nisin could be also used to inhibit biofilm formation (≥93.2%) at a low phage titer (102 PFU ml-1), and low EDTA (1.25 mM) and nisin (9.375 µg ml-1) concentrations. A reduction of 70% in the mature biofilm was possible when 107 PFU ml-1 of P22 phage, 20 mM of EDTA and 150 μg ml-1 of nisin were used in combination. This study revealed that it could be possible to reduce biofilm formation by S. Typhimurium by the use of P22 phage, EDTA and nisin, either alone or in combination. Although, removal of the mature biofilm was more difficult, the triple combination could be successfully used for mature biofilm of S. Typhimurium.