A Pseudomonas putida whole-cell bioreporter for detecting bioavailable copper was constructed by inserting a CueR-regulated sensor element upstream of a promoterless green fluorescent protein (GFP) reporter gene. The constructed bioreporter cells expressed GFP only in response to Cu and Ag when cultivated in different metal salt solutions. M9 supplemented medium provided higher sensitivity compared with LB medium. The optimal test condition was cell suspension with an OD600 of 0.4-0.5 incubated at 30 A degrees C. The detection range of Cu is 1-70 mg/l under optimal test condition in M9 supplemented medium.