This work presents optical enzyme detection system based on the CMOS array photo sensor and I x 3 polymeric enzyme biochip for detecting Escherichia coli in a one-step procedure. This assay, using 4-methylumbelliferyl-beta-D-glucuronide (MUG) as a fluorogenic substrate, had a detection limit of 0.1 U/ml for beta-glucuronidase (GUD), which was approximately equal to a cell concentration of 10(6), CFU/ml of E. coli. MUG was incorporated into lauryl tryptose broth at a final concentration of 100 mu g/ml for immediate verification of the presence of E coli in 1 x 3 polymeric enzyme biochip. The 40 strains of E. coli studied all produced GUD. Of another 36 strains of bacteria tested, one strain (Salmonella choleraesuis subsp. choleraesuis) yielded very small amounts of GUD after 24 h incubation. The optical enzyme detection system was sensitive and rapid.
