The organism must be Escherichia coli
Escherichia coli is a bacterium of the family Enterobacteriaceae.
Escherichia coli is abundant in the commensal flora, particularly in the digestive tract.
Aerobic bacillus, Gram negative, oxidase negative, nitrate positive and which ferments glucose.
* fermentation of sugars: glucose +, lactose +
* reduction of nitrates to nitrites: NO3 +
* metabolism of tryptophan to indole: ind +