Competitiveness and antibacterial potential of bacteriocin-producing starter cultures in different types of fermented sausages

Application of bacteriocin-producing starter cultures of lactic acid bacteria in fermented sausage production contributes to food safety. This is sometimes hampered by limited efficacy in situ and by uncertainty about strain dependency and universal applicability for different sausage types. In the present study, a promising antilisterial-bacteriocin producer, Lactobacillus sakei CTC 494, was applied as a coculture in addition to commercial fermentative starters in different types of dry-fermented sausages. The strain was successful in both Belgian-type sausage and Italian salami that were artificially contaminated with about 3.5 log CFU g(-1) of Listeria monocytogenes. After completion of the production process, this led to listerial reductions of up to 1.4 and 0.6 log CFU g(-1), respectively. In a control sausage, containing only the commercial fermentative starter, the reduction was limited to 0.8 log CFU g(-1) for the Belgian-type recipe, where pH decreased from 5.9 to 4.9, whereas an increase of 0.2 log CFU g(-1) was observed for Italian salami, in which the pH rose from 5.7 to 5.9 after an initial decrease to pH 5.3. In a Cacciatore recipe inoculated with 5.5 log CFU g(-1) of L. monocytogenes and in the presence of L. sakei CTC 494, there was a listerial reduction of 1.8 log CFU g(-1) at the end of the production process. This was superior to the effect obtained with the control sausage (0.8 log CFU g(-1)). Two commercial antilisterial cultures yielded reductions of 1.2 and 1.5 log CFU g(-1). Moreover, repetitive DNA sequence-based PCR fingerprinting demonstrated the competitive superiority of L. sakei CTC 494.