Differentiation of Staphylococci from Iberian dry fermented sausages by protein fingerprinting

The Staphylococci populations in different types of Iberian dry fermented sausages from central-west Spain were identified. A simple electrophoretic method of whole-cell proteins and extracellular protein profiling was evaluated for speed of identification. This study was correlated with a 16S rRNA gene sequence analysis and biochemical identification by API Staph. A total of 81 isolates were identified by SDS–PAGE of the whole-cell proteins. These showed stable profiles in the range 99–14 kDa that were clearly different for the different species, and were grouped into clusters together with the profiles of the eight reference strains. SDS–PAGE of the extracellular protein extracts provided additional characteristic banding patterns for the characterization of the Staphylococcus species present. The whole-cell SDS–PAGE showed that the predominant species was Staphylococcus saprophyticus (61.7%) followed by Staphylococcus aureus (19.7%). The identifications were confirmed by the 16S rRNA gene sequencing and by a BLAST search of the GenBank database. However, the API Staph biochemical identifications were frequently erroneous at the species level. In sum, SDS–PAGE analysis showed itself to be rapid and accurate in identifying the most commonly encountered Staphylococcus isolates in dry fermented sausages.