Influence of Prebiotic Ingredients on the Growth Kinetics and Bacteriocin Production of Lactococcus lactis

Abstract

Prebiotic ingredients are increasingly added to food preparations containing probiotics in order to enhance probiotic survival and growth. Bacteriocins produced by Lactococcus lactis (nisin) have great advantages as a food additive, such as heat stability, nontoxicity and sensitivity to digestive proteases. In this context, the aim of this study was to evaluate the influence of prebiotic ingredients on the fermentation kinetics and antimicrobial activity by Lactococcus lactis subsp. lactis CECT 4434 against Lactobacillus sakei. Lc. lactis was cultivated in MRS medium (Man, Rogosa and Sharpe) supplemented with or without (control) fructooligosacharides (MRS+FOS), polydextrose (MRS+PD) and inulin (MRS+IN). All cultivations were carried out in shaken flasks at 30 °C with agitation speed of 100 rpm. Samples were collected for analyses (biomass, specific growth rate, generation time and antimicrobial activity) every two hours during the 48 h of cultivation. The exponential growth phase of Lc. lactis subsp. lactis CECT 4434 occurred at intervals of 2-8 h for all runs (MRS, MRS+FOS, MRS+PD e MRS+IN). The use of all prebiotic ingredients increased cell biomass, specific growth rate and consequently decreased generation time when compared with control (only MRS). Antimicrobial activity of nisin produced by Lc. lactis subsp. lactis CECT 4434 was detected against Lactobacillus sakei strain.