Proteolytic activities and safety of use of Enterococci strains isolated from traditional Azerbaijani dairy products

摘要

A collection of 147 isolates obtained from 23 samples of traditional Azerbaijani dairy products was screened for the presence of proteolytic enzymes. Six Enterococcus faecalis strains obtained from three cheese samples have been identified as proteinase-producing strains, according to their ability to hydrolyze caseins. RAPD–PCR profiles of their total DNA showed different patterns for strains isolated from different cheese samples. The proteolytic activities of these strains were studied during their growth in milk and in non-proliferative cells system. Isolated strains were able to hydrolyze αS1-, αS2-, β-caseins and BLG albeit to different extents, at optimal pH in the range 6.0–7.2 and optimal temperature in the range 37–45 °C, depending on the strain. Proteolysis was strongly inhibited in the presence of EDTA—specific inhibitor of metalloproteases—but the presence of other types of proteases cannot be excluded. The potential pathogenicity of the strains was evaluated investigating the presence of the genes coding different virulence factors and their resistance to antibiotics. The obtained results yield new information about technological characteristics and safety of studied Enterococci strains from Azerbaijani artisanal dairy products. Many from the isolated strains contribute certainly to the differences in flavor, texture, and taste of Azerbaijani traditional cheeses and could represent new adjunct cultures for the dairy industry.