Effect of some physico-chemical conditions on an immunoassay for viable Escherichia coli.

Viable Escherichia coli can be detected by an immunoassay in which live bacteria captured on antibody-coated paramagnetic beads are induced to synthesize the enzyme beta-galactosidase, which catalyzes the hydrolysis of the slightly fluorescent substrate 4-methyl umbelliferyl-beta-D-galactoside to the highly fluorescent product 7-hydroxy-4-methylcoumarin for detection. The effects of bacterial strain, presence of dead bacteria, and some environmental stresses on assay performance were evaluated.