Bacterial Bioluminescent Biosensors: Applications in Food and Environmental Monitoring

Abstract

Bioluminescence has emerged as an extremely useful and versatile reporter technology. It provides a sensitive, non‐destructive, and real‐time assay that allows for temporal and spatial measurement. The ability to emit light is dependent on the reducing power of the organism; hence, only metabolically active cells can produce light. The direct relationship between viability and light emission allows the use of bioluminescent bacteria to assess the effect of various chemical, biological, and physical signals.

We have constructed a number of recombinant plasmids carrying the lux operon expressed constitutively in many Gram negative and Gram positive bacteria. These plasmids were used to transform a wide variety of bacteria, giving rise to a range of versatile and robust whole cell biosensors with varied applications. The clinical isolate Escherichia coli 16906 was transformed with the pUC19‐derived pLITE27 plasmid to study the antibacterial effect of xanthine oxidase found in bovine and human milk. The self‐bioluminescent strains Salmonella enterica serovar Typhimurium DT104 and E. coli O157 (tox‐) were used to monitor bacterial inactivation and recovery on food surfaces during and after heat treatment. Escherichia coli O157, transformed with the pLITE27 plasmid, was successfully employed to assess the uptake and survival of bacteria within the freshwater protozoa Tetrahymena pyriformis.

Keywords:

• Biosensors
• lux genes
• xanthine oxidase
• food contamination
• protozoa

The authors would like to thank A. Baldwin, J. Hancock, and S. Nelson for their invaluable help. This research was funded by grants EU Framework V with studentships from Wellcome Trust, Nuffield Foundation, and SfAM.