Bioluminescent Listeria monocytogenes provide a rapid assay for measuring biocide efficacy

A recombinant derivative of Listeria monocytogenes 23074, engineered to express the luxAB genes of Vibrio fischeri MJI, has a bioluminescent phenotype that provides a rapid monitor of microbial viability. The antibacterial activity of phenol and chlorhexidine diacetate (Hibitane) was measured using both bioluminescence and viable counts. Concentration exponents were assessed as 7.3 for phenol and 2.63 for chlorhexidine diacetate using bioluminescence, and 8.3 and 2.13 respectively using plate counts. The rapidity of bioluminescence measurement constitutes a major advantage in biocide assessment.