CONICET | Buscador de Institutos y Recursos Humanos

Along with the functional food revolution, the food industry is demanding economical, high-quality and novel ingredients. On the other hand, consumers prefer more stable and safer products with a longer shelf life, high organoleptic standards without chemical preservatives. In this context, the use of bacteriocinogenic Lactic Acid Bacteria (LAB) as a biotechnological strategy constitutes a challenge to the food industry. Although Enterococci are not considered GRAS and their safety remains controversial, they own positive traits that can be useful for technological applications. Enterococci are known to produce a wide range of bacteriocins and some species are being use as probiotics. Bacteriocins are antimicrobial peptides ribosomally synthesized with particular interest since their potential use as biopreservatives in food industry. Enterococcus mundtii CRL35, a strain isolated from an artisanal Argentinean cheese, has a great bioprotector potential due to its Enterocin CRL 35, a bacteriocin active against spoilage and pathogenic microorganisms. On the other hand Lactobacillus curvatus CRL705 from meat origin has a proved technological and bioprotective potential due to its ability to synthesize two bacteriocins, Lactocin 705 and AL705. However, the production of bacteriocins under laboratory conditions does not confirm its effectiveness during a food production process especially on environments different to those of the producer strains. Therefore, the aim of this work was to characterize the behavior of E. mundtii CRL 35 and L. curvatus CRL705 and its bacteriocin production in complex food media such as whey, whey protein concentrate (WPC) and meat. Growth parameters and bacteriocin production of the selected strains was evaluated. Surprisingly, among all substrates, meat extract turned out to be the best growth media for both microorganisms, reaching 9.93 and 8.90 log UFC/ml at 12 h for E. mundtii CRL 35 and L. curvatus CRL 705, respectively. Optimal production of enterocin CRL35 was recorded in WPC (3 x104 AU/ml). The bacteriocin production showed to be appropriate on meat extract, reaching 6.4 x103 and 1.6 x103 AU/ml, for Enterocin CRL 35 and AL 705, respectively. The lowest bacteriocin production was obtained in whey culture (1.8 x103 AU/ml) for E. mundtii while no activity was detected for L. curvatus on this medium. It is worth noting that after 48 h of incubation on meat extract the pH reached to 4.34 for E. mundtii which might contribute even more to enhance microbiological safety of foods. Altogether, the results demonstrate that E. mundtii CRL35 and L. curvatus CRL705 would be good candidates for constitute a bioprotective culture on food systems.