Because FMNH2 production is dependent on a functional electron transport chain, only metabolically active bacteria emit light . Thus, BLI provides a sensitive real-time measurement of the effects of various chemical, biological and physical stimuli on bacterial metabolism . We utilized our bioluminescent Salmonella enterica serotypes to validate our model under a temperature range that bacteria in food products are commonly
exposed to (host to ambient to refrigeration). Therefore we investigated the relationship between cellular metabolic activity, characterized by bacterial light production, and temperature variation. The LY3023414 temperatures selected were 37°C, 25°C and 4°C. Mesophiles, such as Salmonella VS-4718 grow best in moderate temperatures (15-40°C) with normal enzymatic activity. In this experiment luciferase reaction within Salmonella was monitored. At 37°C and 25°C BLI measurements were consistent within Selleck Autophagy inhibitor the replicates of the different serotypes. However, a change in temperature will have an impact on enzyme kinetics. Decreasing temperature, to 4°C, will slow molecular motion and inhibit the luciferase reaction. Decreasing temperature will also decrease the rate of metabolism,
which translates to decreased concentration of substrate, FMNH2, available for the luciferase reaction. At 4°C we observed an expected reduction in bioluminescent signal compared to readings at the two higher temperatures, 37°C and 25°C (data not shown). However, over the time required (approximately 1 min) Loperamide to complete BLI measurements at 25°C we observed a rapid increase in the bioluminescent signal between the first and the last wells read. We found that luciferase activity is restored shortly after removal from refrigeration temperature, so temperature effect is minimal after introduction to ambient temperatures (≥ 25°C). These results were consistent and validated that our reporting system using bioluminescent Salmonella can be successfully applied to monitor within
a temperature range that bacteria in food products are commonly exposed to. The stage on our luminometer has adjustable temperature with the lowest temperature setting being 25°C. Future work will include the development of a mechanism for maintaining plates at refrigeration temperatures while on the reading stage of the instrument to overcome this limitation. Development of chicken skin assay for real-time monitoring of bioluminescent Salmonella enterica Salmonella presents a major problem for the poultry industry due to its persistence during the processing of chicken carcasses and few options exist that completely eliminate the bacteria from the chicken carcasses besides proper cooking.