DETECTION OF FECAL POLLUTION IN WATER BY AN ESCHERICHIA-COLI UIDA GENE PROBE

This paper describes a method for the detection of faecal pollution in water, using a gene probe based on the Escherichia coli K-12 gene, uidA, which encodes beta-glucuronidase (GUD). GUD has been reported to be produced by 97-99.5% of E. coli and we report that all E. coli and Shigella strains tested, were reactive with the uidA gene probe, whether or not they were actively producing GUD. Other faecal and environmental bacteria tested were not reactive with the uidA gene probe. The water testing procedure described is based on the membrane filter technique and uses a non-selective enrichment period of 10 h at 37-degrees-C prior to the membranes being hybridised with the uidA gene probe, after which up to 500 faecal coliforms could be counted per membrane.