On-line monitoring of gene expression

Gene expression in cultures of Escherichia coli has been determined in situ and on-line by the use of an electrochemical sensor. Intact bacteria were used to monitor the induction of the lacZ gene; the onset of stationary phase was also monitored, using a reporter gene fused to the RpoS-dependent promoter of the osmY gene. The technique described can in principle be used to determine the activity of any promoter, with a variety of reporter genes. This technology is non-intrusive, allows real-time monitoring of gene expression, and will be useful in the study of growth regulation and development.