Amperometric measurement of copper ions with a deputy substrate using a novel Saccharomyces cerevisiae sensor

The first microbial biosensor to detect Cu 2+ by an amperometric method has been developed. For this purpose, recombinant Saccharomyces cerevisiae strains are suitable as the microbial component. These strains contain plasmids with the Cu 2+-inducible promoter of the CUP1-gene from Saccharomyces cerevisiae fused to the lacZ-gene from E. coli. On this sensor the CUP1 promoter is first induced by the Cu 2+-containing probe and subsequently lactose is used as a deputy substrate to make the measurement. If Cu 2+ is present in the sample, these recombinant strains are able to utilize lactose as a carbon source, which leads to alterations in the oxygen consumption of the cells. The sensor measured Cu 2+ in a concentration range between 0.5 and 2 mM CuSO 4. In addition, an indirect amperometric measurement principle was developed which allows the detection of samples containing Cu 2+ and fast biodegradable substances.