RESUMO
The development of the natural microbial populations during traditional processing of the "Salame di Senise", a typical little known sausage produced in the South of Italy, was investigated by using molecular and physiological techniques for taxonomic identification and technological characterization of strains. The application of RAPD-PCR over more than 90 colonies made it possible to isolate 18 bacterial and two yeast biotypes identified by partial rDNA sequencing as belonging mainly to three species of Bacillus, three species of Lactobacillus, three species of Staphylococcus and Debaryomyces hansenii. The physiological analyses revealed that the isolates belonging to Lactobacillus genus were the most acidifying, whereas Staphylococcus strains did not develop significant proteolytic and lipolytic activities. Interestingly, some Bacillus strains produced the highest values of proteolytic and lipolytic activities. The results for the technological properties of Bacillus strains isolated from this Southern Italian sausage, made without a selected starter, suggest that Bacillus strains, always present in meat curing, could play a role in the development of texture and organoleptic characteristics of the sausages.
RESUMO
Artisanal and industrial sausages were analyzed for their aerobic, heat-resistant microflora to assess whether new emerging pathogens could be present among Bacillus strains naturally contaminating cured meat products. Sixty-four isolates were characterized by randomly amplified polymorphic DNA (RAPD)-PCR and fluorescent amplified fragment length polymorphism (fAFLP). The biotypes, identified by partial 16S rRNA gene sequence analysis, belonged to Bacillus subtilis, Bacillus pumilus, and Bacillus amyloliquefaciens species. Both RAPD-PCR and fAFLP analyses demonstrated that a high genetic heterogeneity is present in the B. subtilis group even in strains harvested from the same source, making it possible to isolate 56 different biotypes. Moreover, fAFLP analysis made it possible to distinguish B. subtilis from B. pumilus strains. The strains were characterized for their toxigenic potential by molecular, physiological, and immunological techniques. Specific PCR analyses revealed the absence of DNA sequences related to HBL, BcET, NHE, and entFM Bacillus cereus enterotoxins and the enzymes sphingomyelinase Sph and phospholipase PI-PLC in all strains; also, the immunological analyses showed that Bacillus strains did not react with NHE- and HBL-specific antibodies. However, some isolates were found to be positive for hemolytic and lecithinase activity. The absence of toxigenic potential in Bacillus strains from the sausages analyzed indicates that these products can be considered safe under the processing conditions they were produced; however, great care should be taken when the ripening time is shortened, particularly in the case of traditional sausages, which could contain high amounts of Bacillus strains and possibly some B. cereus cells.
