The name is obtained using the conventaional method -:

(i) First capital letter of the name comes from the genus of the organism Escherichia is ‘E’.

(ii) Second two small letters comes from the species of cells from which they are isolated i.e. ‘co’.

(iii) Letter R is derived from the name of strain  of the bacteria i.e. Escherichia coli Ry_ 13.

(iv) Roman number indicate the order in which enzymes were isolated from that strain of bacteria .