Comparative electrophoretic polymorphism of esterases and other enzymes in Escherichia coli

The electrophoretic polymorphism of esterases was compared with that of other enzymes in Escherichia coli populations by investigating allozyme distribution of four esterases (A, B, C and I) within both the subspecific groups I, II and III and the new groups A, B1, B2, C, D and E, which have been distinguished by electrophoretic analysis of 11 and 35 enzymes respectively in the 72 reference strains of the ECOR collection. Electrophoretic distribution of esterases was distinct for each of the three subspecific groups as indicated by distributions of allozymes and electrophoretic types (distinctive combination of allozyme for the four esterases). Esterase polymorphisms of the three subspecific groups appeared to have similar features to those of three previously studied natural populations of strains obtained from human and animal gastro-intestinal tracts and extra-intestinal infections in humans. Multiple correspondence analyses using data obtained from the four esterases and the 11 other enzymes also distinguished the groups A, B1, B2, C, D and E. All strains of group B2 showed the B2 electrophoretic pattern of esterase B, which appeared to be a marker of a distinct cluster of strains frequently implicated in extra-intestinal infections.