Near on-line detection of enteric bacteria using lux recombinant bacteriophage

Abstract

The potential for a revolution in microbial testing can be perceived with the near on-line detection of indicator microorganisms. By definition, these are microorganisms present in significant numbers within a food which, while not pathogenic, can be related through increasing count to the increased probability of pathogen contamination. We have used recombinant lux+ bacteriophage to detect enteric indicator bacteria without recovery or enrichment in 50 min, provided that they are present at levels greater than 10(4) g-1 or cm-2. After a 4-h enrichment, samples having enteric counts of 10 g-1 or cm-2 can be distinguished from background.

On-line monitoring of gene expression

“…These results are in agreement with previous results obtained with a colorimetric assay (Weichart et al, 1993). (Heitzer et al, 1994;Kodikara et al, 1991;Leibiger et al, 1998;Valdez et al, 1998), the amperometric biosensor reported here has several advantages. These include high sensitivity, simplicity, and the fact that the electrodes are disposable.…”

“…Such a system is especially advantageous in the study of developmental or growth-phase-related genes. Recently, several publications have described the possibility of using reporter genes such as lux or g f p for on-line, or semi-on-line, non-invasive monitoring (Heitzer et al, 1994;Kodikara et al, 1991 ;Leibiger et al, 1998;Valdez et al, 1998).…”

Bacterial luciferase reporters: The Swiss army knife of molecular biology

“…By introducing an enrichment step the limit of detection can be lowered to as little as 10 cfu/g. 80 The same approach with similar low limits of detection has been applied for the detection of L. monocytogenes in various food matrices and environmental samples. 81 Other authors have used a more sophisticated approach by generating bacteriophages harbouring the luxI gene.…”

lux genes and the applications of bacterial bioluminescence

“…A revolution in microbial testing can, however, be perceived with the near on-line detection of indicator micro-organisms (Kodikara et al, 1991). By definition, these are micro-organisms present in significant numbers within a food which, while not pathogenic, can be related through increasing count to the increasing probability of pathogen contamination.…”