The impact of commercial prebiotics on the growth, survival and nisin production by Lactococcus lactis 537 in milk

Abstract

In this work we investigated the potential of a new dairy-based fermented food which contains a nisin producing Lactococcus lactis strain with biopreservative function and a prebiotic. Lc lactis 537 was incubated in ultrahigh temperature (UHT) skim milk in the presence of 8 different commercially available prebiotics (inulin, fructooligosaccharide, xylooligosaccharide, lactulose, gum arabic, maltodextrin, isomaltooligosaccharides, galactooligosaccharides) at 3% concentration. The growth of Lc. lactis 537 was found to be enhanced in the presence of inulin only, as compared to in milk without prebiotic. Acidification was minimal, with all milks with or without prebiotic remaining above pH 6. Survival during storage for 14 days at 4 °C was high with or without prebiotic, with less than a 1-log CFU/mL reduction in viability seen. Antimicrobial production by Lc. lactis 537 was evaluated and found to be significantly higher when cells were grown in the presence of inulin. A nisB mutant of Lc. lactis 537 did not have any antimicrobial activity with or without prebiotic, thus demonstrating the effect was due to nisin. The findings of this study suggest that inulin is the most promising prebiotic inclusion for the development of a milk-based symbiotic product containing Lc. lactis 537.