How Novel Methods Can Help Discover More Information about Foodborne Pathogens

Abstract

Considerable emphasis is being placed on quantitative risk assessment modelling as a basis for regulation of trade in food products. However, for models to be accurate, information about the behaviour of potential pathogens in foods needs to be available. The question is how to obtain this knowledge in a simple and cost effective way. One technique that has great potential is the use of reporter bacteria which have been genetically modified to express a phenotype that can be easily monitored, such as light production in luminescent organisms. Bacteria carrying these (lux) genes can easily be detected using simple luminometers or more sophisticated low light imaging equipment.By monitoring light output from these bacteria over time, it can easily be determined if the organism is growing (resulting in an increase in light emission), is dead (causing a decrease in light production) or is injured (light output remains constant). The use of imaging systems allows the response of bioluminescent bacteria to be studied directly on the food, making the technique even more useful. Applications of bioluminescence are discussed below and include use as reporters of gene expression; biocide efficacy and antibiotic susceptibility; sub-lethal injury; adhesion and biofilm formation; the microbial ecology of foods; pathogenesis; and as biosensors.

Investigation of the Use of a Cocktail of Lux-Tagged Cronobacter Strains for Monitoring Growth in Infant Milk Formulae

“…Milk components can influence biofilm formation by C. sakazakii (7), and biofilms contribute to persistence of the pathogen on food contact surfaces (75). Lux-tagged strains may also be employed to investigate biocide efficiency or examine growth and survival with in vitro (i.e., cell culture) and in vivo models of infection ( 11).…”

Use of bioluminescence imaging to monitor Campylobacter survival in chicken litter

“…Bioluminescent bacteria have been regarded as an important tool for studying pathogens in hosts and the environment (Griffiths 2000). Advantages of bioluminescence imaging include real-time monitoring of the pathogens and the simplicity and sensitivity of the approach (Brovko and Griffiths 2007).…”

“…Background signals were quantified similarly, using ROIs of samples that were not spiked with the bioluminescent bacteria. An increase or decrease in emissions indicates the organism's growth or death, respectively (Griffiths 2000).…”

“…A promising approach is using bioluminescence technology, which can facilitate real-time monitoring of bacteria under different environmental conditions (Griffiths 2000). Bioluminescent bacterial cells can be genetically engineered by introducing the genes that encode the luciferase enzyme, which is responsible for light production in several naturally luminescent bacteria (Engebrecht and Silverman 1984).…”

Assessing Ecotoxicity in Marine Environment Using Luminescent Microalgae: Where Are We At?

“…More recently, in food industry (for a review see [40]), luminescence tools permit to follow the survival of pathogenic microorganisms and the expression of bacterial toxins in foods. Interestingly, specific bacteriophages genetically transformed with the Lux genes allow the direct detection of food pathogens [41]. Genetically modified whole-cell bioreporters using luminescence detection are practical tools for the detection and monitoring of contaminants in environmental context.…”