Abstract: The assay conditions and procedure were studied in this paper. Firstly, Escherichia coli was pre-incubated in TB for 12 hours. Then 0.1ml aliquots were taken to be combined with 0.05ml polymyxin B(100μg/ml) and 0.1ml MUG(4-methylum belli feryl-β-D-glucuro nide)(0.2mg/ml) and incubated at 37℃ for 45min. Finaly 1.75ml Gly-NaOH buffer(0.2mol/L, pH10.4) were added to end the reaction. The the two-step fluorescent method is better than that of MPN(most probable number), which is widely used for the detection of Escherichia coli,and was quantitatively close to the traditional MPN method.

Key words: two-step fluorescent method, detection, Escherichia coli