Faecal coliforms

Bacteria which ferment lactose and produce gas in lauryl sulphate broth within a period of 48 +/- 2 h when incubated at 37 +/- 0,2 °C, and in addition produce indol in tryptone broth within 24 +/2 2 h when incubated at 44 +/- 0,2 °C