Characterization of Micrococcaceae isolated from Iberian dry-cured sausages

The populations of Micrococcaceae in different types of Iberian dry-cured sausages from central-west Spain were characterized and their technological and antimicrobial properties determined in order to evaluate their suitability as starter cultures in dry-cured sausage manufacture. Of a total of four hundred strains isolated from two manufacturers, one hundred and sixty-six were selected to evaluate nitrate reductase, proteolytic, lipolytic, and antimicrobial activities, and growth at different values of pH and water activity (a(w)). Most of the strains were identified as Staphylococcus except for eight isolates assigned to Kocuria spp. The species most often isolated was Staphylococccus xylosus. Others were, in descending order of abundance, S. aureus, S. lugdunensis, S. saprophyticus, S. sciuri, S. chromogenes, and S. capitis. The distributions of the minority Staphylococcus species were different for the two manufacturers. All the investigated strains were able to grow at pH and a(w) greater than 5.0 and 0.85, respectively, the values usually found in Iberian dry-cured sausages. Five S. xylosus strains showed antimicrobial activity against some indicator strains which were investigated. Seven strains with the best properties were pre-selected and tested for their lipolytic and proteolytic activities against pork fat and myofibrillar and sarcoplasmic pork proteins, respectively, and for their low biogenic amines production. Most of the strains showed proteolytic and lipolytic activities, but none produced histamine, tyramine, phenylethylamine, or spermine. Three strains, identified as Staphylococcus xylosus, possess useful properties which make them candidates for testing as starter cultures in pilot processing of Iberian sausages.