isopropyl-thiogalactoside and chlorophenol-red-galactopyranoside

We describe an electrochemical measurement technique that enables bioelectronic measurements of reporter proteins in living cells as an alternative to traditional optical fluorescence. Using electronically programmable microfluidics, the measurement is in turn used to control the concentration of an inducer input that regulates production of the protein from a genetic promoter. The resulting bioelectronic and microfluidic negative-feedback loop then serves to regulate the concentration of the protein in the cell. We show measurements wherein a user-programmable set-point precisely alters the protein concentration in the cell with feedback-loop parameters affecting the dynamics of the closed-loop response in a predictable fashion. Our work does not require expensive optical fluorescence measurement techniques that are prone to toxicity in chronic settings, sophisticated time-lapse microscopy, or bulky/expensive chemo-stat instrumentation for dynamic measurement and control of biomolecules in cells. Therefore, it may be useful in creating a: cheap, portable, chronic, dynamic, and precise all-electronic alternative for measurement and control of molecules in living cells.

Topics: beta-Galactosidase; Chlorophenols; Electrochemical Techniques; Electrons; Escherichia coli; Escherichia coli Proteins; Feedback, Physiological; Galactose; Galactosides; Gene Expression Regulation, Bacterial; Genes, Reporter; Isopropyl Thiogalactoside; Lac Operon; Lac Repressors; Microfluidic Analytical Techniques; Oxidation-Reduction; Phenolsulfonphthalein; Promoter Regions, Genetic

A liquid, colorimetric presence-absence coliphage detection method based on the induction of beta-galactosidase by Escherichia coli is described. The release of beta-galactosidase in the medium due to lytic cell infections by coliphages permits the hydrolysis of a yellow chromogenic substrate that develops into a distinct red coliphage positive sample, while a coliphage negative sample remains yellow. This method has proven to be rapid, simpler to perform than an agar medium assay, easy to read and interpret, inexpensive, and highly sensitive.

Topics: beta-Galactosidase; Chlorophenols; Coliphages; Colorimetry; Enzyme Induction; Escherichia coli; Evaluation Studies as Topic; Galactosides; Isopropyl Thiogalactoside; Sensitivity and Specificity; Sewage; Virology; Water Microbiology; Water Supply