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The longevity of phage to Salmonella typhimurium on a magnetostrictive sensor platform

Fei Sun, Xue-mei Ye, Bryan A.Chin, Jing Hu

Phage was immobilized onto the sensor using physical adsorption and stored at temperatures of 25ºC (room temperature), 45ºC and 65ºC, respectively, and then the longevity of phage to Salmonella typhimurium was investigated by studying the binding activity using a magnetostrictive platform at a predetermined schedule. Changes in the fundamental resonance frequency of sensors after exposure to 1 mL of 1×109cfu/mL of S. typhimurium were recorded over the testing period. The shift in resonance frequency was attributed to the binding of bacteria to phage immobilized sensor, which was confirmed by Scanning Electron Microscopy (SEM) micrographs. The results showed that at each temperature, the binding ability to S. typhimurium decreased dramatically at the first 3 days, then decreased very slowly over the testing period, and the longevity of phage on the magnetostrictive sensor platformwas longer than 30 days at all tested temperatures. Therefore, it is reasonable to get the conclusion that phage immobilized sensors will be quite suitable to use in field assay at high temperature due to its very good stability.