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We describe a novel approach to assess toxicity to the free‐living nematode Caenorhabditis elegansthat relies on the ability of firefly luciferase to report on endogenous ATP levels. We have constructed bioluminescent C. eleganswith the lucgene under control of a constitutive promoter. Light reduction was observed in response to increasing temperature, concentrations of copper, lead and 3,5‐dichlorophenol. This was due to increased mortality coupled with decreased metabolic activity in the surviving animals. The light emitted by the transgenic nematodes gave a rapid, real‐time indication of metabolic status. This forms the basis of rapid and biologically relevant toxicity tests.

This study determined that the bacterial luciferase fusion gene (luxAB) was not a suitable in vivo gene reporter in the model eukaryotic organisms Saccharomyces cerevisiaeand Caenorhabditis elegans. LuxAB expressing S. cerevisiaestrains displayed distinctive rapid decays in luminescence upon addition of the bacterial luciferase substrate, n‐decyl aldehyde, suggesting a toxic response. Growth studies and toxicity bioassays have subsequently confirmed, that the aldehyde substrate was toxic to both organisms at concentrations well tolerated by Escherichia coli. As the addition of aldehyde is an integral part of the bacterial luciferase activity assay, our results do not support the use of luxreporter genes for in vivo analyses in these model eukaryotic organisms.