Signal Enhancement in ATP Bioluminescence to Detect Bacterial Pathogens via Heat Treatment

An ATP bioluminescence assay is frequently in the food industry as a commercially-available bacterial monitoring method because it is convenient and can monitor viable cells in food. However, such an assay suffers from low sensitivity and thus has limitations in monitoring highly pathogenic bacteria. In this study, we describe a method that improves the sensitivity by increasing the amount of ATP that is released from bacterial cells by subjecting the samples to heat treatment. When treated for 10 min at a temperature of 25 to 95 degrees C in phosphate buffered saline (PBS) containing Escherichia coli O157:H7 or Salmonella enteritidis or Bacillus cereus at various concentrations, the relative luminescence unit (RLU) increased several times. Due to signal enhancement, the detection limit (LOD) of the ATP bioluminescence assay improved by about an order of magnitude in milk-containing microorganisms. Our results indicate that the simple heating step on the food samples before measurement is useful to improve the sensitivity of the ATP bioluminescence assay for bacterial detection.