Characterization of five esterases from Listeria monocytogenes and use of their electrophoretic polymorphism for strain typing.

Esterases from Listeria monocytogenes strains isolated from cheeses were analyzed by starch gel electrophoresis. Five esterases, numbered from EST 1 to EST 5 in order of decreasing anodal migration, were identified. The EST 1, EST 3, EST 4, and EST 5 set was most active toward alpha-naphthyl propionate, while EST 2 was most active toward alpha-naphthyl acetate. Results from inhibitor studies suggest that all of these esterases were EC class 3.1.1.1 carboxylesterases, except that EST 1 and EST 3 also showed some sensitivity to parahydroxymercuribenzoate. Polymorphism of these five esterases was observed in the population. Twelve esterase patterns were defined and used to subdivide serotypes.