MUG can be incorporated into almost any medium for use in detecting E. coli. But some media such as EMB, which contain fluorescent components, are not suitable, as they will mask the fluorescence of MU. When MUG is incorporated into LST medium, coliforms can be enumerated on the basis of gas production from lactose and E. coli are presumptively identified by fluorescence in the medium under longwave UV light, thus it is capable of providing a presumptive identification of E. coli within 24 h (18, 28).