Physiological and molecular techniques for the study of bacterial community development in sausage fermentation

The development of the microbial community involved in the production process of Italian dry sausage was investigated using physiological analysis and molecular techniques for strain typing and taxonomical identification. A cycle of sausage production was followed collecting samples during the 2 months of ripening process. Microbiological analysis allowed the identification of the main bacterial groups responsible for the fermentation process as lactobacilli and coagulase-negative staphylococci. The use of a polymerase chain reaction-based technique of strain typing, RAPD fingerprinting, demonstrated that the environmental parameters interact to select a limited number of strains that dominate the fermentation process. The staphylococcal populations were characterized for their physiological properties and the two dominant strains were identified as Staphylococcus xylosus and Staph. sciuri. The use of 16S rDNA sequencing allowed the definition of the taxonomical position of the two dominant strains of lactic acid bacteria, as belonging to Lactobacillus sake and Lact. plantarum.