On-line monitoring of gene expression

Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel Author for correspondence: Eliora Z. Ron. Tel: + 972 3 6409379. Fax: + 972 3 6414138. e-mail: eliora@post.tau.ac.il Address: Institute of Plant Physiology & Microbiology, Free University of Berlin, Berlin 14195, Germany. ABSTRACT 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. Keywords: biosensors, reporter gene, on-line monitoring, β-galactosidase Abbreviations: PAP, p -aminophenol; PAPG, p -aminophenyl β-D-galacto-pyranoside.