Construction of tracer plasmids for Bacillus sphaericus 1593 utilizing the xylE gene from Pseudomonas putida

Genetically engineered microorganisms (GEMS) released into the environment must be traceable in order to accurately assess their impact on the area of release. Tracer genes other than those that introduce antibiotic resistance are preferred for use in identifying genetically engineered strains. In this study, we describe the construction of a series of tracer plasmids for use in Bacillus sphaericus using the xylE gene from the Pseudomonas putida TOL plasmid. This gene codes for the enzyme catechol 2,3-dioxygenase which converts the colorless substance catechol to 2-hydroxymuconic semialdehyde, a yellow product which is easily detected. Colonies of cells which express the xylE gene turn yellow shortly after being exposed with a solution of catechol.