KlHIS4-modulated histidine auxotrophy in yeast and characterisation of a KlHIS4-lacZ-based cadmium and copper biosensor

Based on the effects of cadmium and copper on KlHIS4 transcription when expressed in either Kluyveromyces lactis or Saccharomyces cerevisiae, a yeast biosensor is presented. It consists of a lacZ fused to a KlHIS4 447 bp long promoter expressed in K. lactis, and as control, a second fusion with a shorter promoter not regulated by metals. This eukaryotic system can be used to detect cadmium and copper concentrations of 0.3–3 mM (or higher) within minutes using X-GAL filter assay and other variants of β-galactosidase assays developed in multititer wells.