Characterization of Micrococcaceae isolated from dry fermented sausage

摘要

One hundred Micrococcaceae strains were isolated from two types of naturally fermented dry sausages at four different stages of the ripening process in order to select the most suitable strains according to their technological characteristics including antimicrobial activity against foodborne pathogens. Identification of the isolates revealed that 91 belonged to genus Staphylococcus, whereas 5 were identified as Kocuria varians, 2 as Arthrobacter agilis and 2 as Dermacoccus nishinomiyaensis. The species most often isolated was S. saprophyticus (22), followed by S. carnosus (20) and S. xylosus (10). The isolated strains of S. xylosus (10 isolates), S. carnosus (20 isolates) and K. varians (five isolates) were further characterized. A large majority of the above strains was able to grow in the presence of 10 and 15 NaCl to reduce nitrates at 18degreesC and to hydrolyse casein. The majority of the strains of S. xylosus produced acetoin and 30 of them hydrolysed tributyrin. All S. xylosus strains and a large majority of S. carnosus and K. varians strains exhibited an anti-listerial activity against three Listeria monocytogenes strains. The enzymatic potential of the strains was evaluated using the API ZYM system. S. xylosus strains exhibited high beta-galactosidase and esterase-lipase activities, whereas S. carnosus strains indicated strong cysteine aminopeptidase and acid phosphatase activities and K. varians indicated very weak activities of the enzymes tested A rapid characterization of the above strains according to their enzymatic pattern could be achieved in order to follow the strains selected as starter cultures during sausage fermentation. The contribution of the selected strains to a possible inhibition of L. monocytogenes in situ on fermented meats would be of considerable interest to enhance the hygienic quality of these products.