Here we describe an alternative approach to currently used cytotoxicity ana
lyses through applying eukaryotic microbial biosensors. The yeast Saccharom
yces cererisiae was genetically modified to express firefly luciferase, gen
erating a bioluminescent yeast strain, The presence of any toxic chemical t
hat interfered with the cells' metabolism resulted in a quantitative decrea
se in bioluminescence. In this study, it was demonstrated that the Luminesc
ent yeast strain senses chemicals known to be toxic to eukaryotes in sample
s assessed as nontoxic by prokaryotic biosensors. As the cell wall and adap
tive mechanisms of S. cerevisiae cells enhance stability and protect from e
xtremes of pH, solvent exposure, and osmotic shock, these inherent properti
es were exploited to generate a biosensor that should detect a wide range o
f both organic and inorganic toxins under extreme conditions.