Competitiveness of the bacteriocinogenic strain Enterococcus mundtii CRL35 for meat fermentation.

VILDOZA, MARIA JOSÉ; SAAVEDRA, LUCILA; SESMA, FERNANDO; VIGNOLO, GRACIELA; FADDA, SILVINA

Istambul

Simposio; FoodMicro 2012. 23rd. International ICFMH Symposium; 2012

ICFMH

Enterococcus species, a group of lactic acid bacteria (LAB), are ubiquitous microorganisms which constitute a large proportion of the autochthonous microbiota found in artisanal fermented foods. Enterococcus mundtii CRL35, isolated from artisanal Argentinean cheese, was reported as a bioprotector culture (BC) because of its listeriaactive bacteriocin production (enterocin CRL35). Considering that this species has also been detected as part of the natural microbiota of Argentinean regional sausages; the aim of this work was to evaluate the competitiveness of E. mundtii CRL35 during the meat fermentation process. In vitro analyses were carried out in a sterile meat fermentation model (MFM) with and without curing additives (CA) (100 ppm NO2, 70 ppm ascorbic acid, 3% NaCl, 0.75% glucose, 0.75% sucrose). E. mundtii CRL 35 showed optimal growth and acidification in MFM with a maximal bacterial growth at 24 h with curing agents (8.6 Log CFU /ml; pH=4.3) and without CA (8.8 log CFU/ml; pH=4.4). Interestingly, a higher bacteriocin production (9.6 X103 UA/ml) at 24 h, was observed in the presence of CA. In order to understand the effect of CA in bacteriocin activity, expression of munA and mun B genes, enconding for the bacteriocin peptide and the ABC-transporter, respectively; under the presence and absence of the curing mixture were analyzed by Real Time PCR. These results demonstrated that the expression of bacteriocin genes was not affected by CA addition. On the other hand, Listeria time-kill curves using synthetic enterocin CRL35 showed that CA improves the antimicrobial activity of this peptide. These results suggest that the stimulatory effect of CA might be due to interactions between these compounds and the protein itself. Besides, E. mundtii CRL35 was able to hydrolyze sarcoplasmic proteins as another important technological feature. In summary, E. mundtii CRL35 may find a practical application as a novel functional starter culture for sausage fermentation ensuring hygienic and sensorial quality in the final product.Enterococcus mundtiiListeria expression of munA and mun B genes, enconding for the bacteriocin peptide and the ABC-transporter, respectively; under the presence and absence of the curing mixture were analyzed by Real Time PCR. These results demonstrated that the expression of bacteriocin genes was not affected by CA addition. On the other hand, Listeria time-kill curves using synthetic enterocin CRL35 showed that CA improves the antimicrobial activity of this peptide. These results suggest that the stimulatory effect of CA might be due to interactions between these compounds and the protein itself. Besides, E. mundtii CRL35 was able to hydrolyze sarcoplasmic proteins as another important technological feature. In summary, E. mundtii CRL35 may find a practical application as a novel functional starter culture for sausage fermentation ensuring hygienic and sensorial quality in the final product.Enterococcus mundtiiListeria