Detecting sensitivity of S. typhimurium on fresh produce by phage-based magnetostrictive biosensors

The magnetostrictive (ME) biosensors have been developed to detect pathogen rapidly and sensitively in fresh produce. The effects of concentration and incubated time of S. typhimurium enrichment on the detection sensitivity were investigated in this study. The concentrations ranging from 5 × 102 to 5 × 108 CFU/mL with incubated time of 22 h, and incubated time ranging from 5 h to 22h with the concentration of 5 × 102 CFU/mL were tested. The results showed that the higher concentration and longer incubated time, the more frequency changes due to the more bacteria binding on the ME biosensors. The micrographs by optical microscope were used to verify the bacteria binding on ME biosensors. The student t-test calculation was also used to analysis the difference between measurement and control sensors. The limit of detection (LOD) for phage-based magnetostrictive biosensors on fresh tomatoes was statistically determined to be lower than 5 × 102 CFU/mL for 5 h enrichment with a confidence level of difference higher than 98% (p<0.05).