Development and Application of Bacterial Bioreporter System for Monitoring Antibiotic Levels in Animal-Based Food Sources

The aim of this study was to develop and apply a high throughput and cost effective method for screening food samples for antibiotic contamination. This method can be used to reduce the number of samples that have to be analysed using expensive chemical methods that are at currently being used for determining antibiotic concentrations. The primary objective of this study involved the construction of a macrolide sensitive bacterial bioreporter, which can be used to detect the levels of macrolide antibiotics in meat samples. The bioreporter was constructed by merging a macrolide promoter region to a bioluminescent signalling gene like the lux operon, this fused segment was then cloned into a suitable vector and transformed to a host E. coli along with the repressor (producing) plasmid. The bioreporter works in the presence of macrolides, when the repressor protein is released from the promoter region, resulting in the expression of the lux operon, which produces light. This light signal can be used for the detection and estimation of macrolide antibiotics using a luminometer. The secondary objective was to use the macrolide bioreporter along with a previously constructed tetracycline bioreporter to measure antibiotic concentrations in bovine meat samples acquired from EVIRA (Finnish Food Safety Authority). On analysis of the resulting luminescence data, calculated concentrations of oxytetracycline were found to be in correlation to the data acquired from EVIRA and also using solid meat samples in assays, instead of extracted muscle fluid produced more accurate results. This shows the usability of bioreporters in the detection of antibiotics in animal-based foods from different sources. The resulting data can also be used to monitor and control the spread of antibiotic resistance through animal farms