Luciferase and fluorescent protein as dual reporters analyzing the effect of n-dodecyltrimethylammonium bromide on the physiology of Pseudomonas putida

With the growing interest in using surfactants to improve microbial cell performance for whole-cell biocatalysis and bioremediation, understanding the interactions between surfactants and bacteria is of great importance. By using cyanine fluorescent protein (CFP) and bacterial luciferase (LUX) as dual bioreporters, the effects of n-dodecyltrimethylammonium bromide (DTAB) on the whole cells and intracellular proteins in Pseudomonas putida cultures were quantitatively and systematically studied. The dual reporter system was shown to be a useful indicator to assess the effect of DTAB treatment on whole-cell metabolic activity, membrane permeability, and cellular enzyme activity. CFP was useful to assess the leakage of intracellular enzymes and the lysis of cells and was able to reflect the activities of most cellular enzymes, while LUX reflected the permeability of cell membranes and cellular metabolic activity. The validity of CFP-LUX dual bioreporters was further confirmed by detecting changes in extracellular proteins, membrane potential, oxygen consumption rate (OUR), and intracellular catechol 2,3-dioxygenase (C23O) activity with the addition of DTAB. The dual LUX-CFP bioreporter is a useful tool for analyzing the surfactant-bacterium interactions for biotechnological applications.