A bioluminescent reporter strain utilizing the lower pathway promoter (Pm) of the xyl operon of Pseudomonas: optimization of a bioassay for m-toluate

A genetically modified strain of Pseudomonas putida mt-2 containing the intact TOL plasmid and a plasmid with the Pm-lux gene has been constructed. The bioluminescence activity of this strain was tested using seven organic compounds and derivatives, including m-toluate. Gene expression was monitored on the basis of the maximum light production of the strain after the addition of the inducer. The magnitude of the bioluminescent response was determined for each compound, revealing the following order: m-methyl benzyl alcohol>m-toluate>toluene>m-xylene>benzoate>p-xylene>o-xylene. Bioluminescence activity of the strain was also determined under different conditions of temperature, medium composition, additional carbon sources, nitrogen and phosphate. These results showed the importance of above conditions on the bioluminescence activity of tested strain. These results demonstrate the capability of such a constructed strain to detect a group of structurally related environmental contaminants and suggest the potential for its use as a rapid field analytical tool.