2. Materials and methods
2.1. Enterococci isolation, phenotypic and genetic identification
Silverside (O. platensis) is a marine fish that inhabits the coast of South America. It is found in template or cold water ( Sampaio, 2006). It possesses meat of excellent quality. As a consequence, it represents an important resource in the Argentine market (Ministerio de Agricultura, Ganadería y Pesca de la República, Argentina, 2015). Many LAB strains were isolated from silverside intestine sampled in the Patagonian region of Argentine according to Marguet, Vallejo, Sierralta Chichisola, and Quispe (2011). The contents from intestinal tract of silverside specimens were homogenized in 1 ml of sterile saline solution. An aliquot of the homogenates was inoculated into De Man, Rogosa and Sharpe (MRS) broth (Biokar Diagnostics, Beauvais, France) and incubated at 25 °C for 6 h. Then the enrichments were plated onto MRS supplemented with nalidixic acid (20 mg/l) and cycloheximide (10 mg/l) and incubated at 25 °C for 48 h.