Characterization of Lactococcus lactis 11/19-B1 Isolated from Kiwi Fruit as a Potential Probiotic and Paraprobiotic

Abstract

Probiotics are live bacteria used as food additives that are beneficial to human health. Lactococcus lactis 11/19-B1 strain isolated from kiwi fruit stimulates innate immunity in silkworms. Intake of yogurt containing the living 11/19-B1 strain significantly decreases the level of low-density lipoproteins (LDLs) in high-LDL volunteers and improves atopic dermatitis in humans. In this study, the probiotic properties of the 11/19-B1 strain, such as sensitivity to antimicrobial compounds, biogenic amine production, some virulence genes for human health, antimicrobial activity, tolerance to gastric acid and bile acids, and ability to adhere to the intestinal mucosa, were evaluated. The 11/19-B1 strain did not show resistance to the tested antimicrobial compounds except cefoxitin and fosfomycin. In addition, no production of amines that can harm humans, the antimicrobial activity required for probiotics, and the absence of adhesion to Caco-2 cells suggest that it is unlikely to attach to the intestinal epithelium. The 11/19-B1 strain grew in 0.3% but not in 1% bile salt. In the presence of 2% skim milk, the survival rate of the 11/19-B1 strain under simulated gastrointestinal tract conditions was 67% even after 4 h. These results indicate that the 11/19-B1 strain may function as a probiotic or paraprobiotic to be utilized in the food industry.

Keywords: Lactococcus lactis; paraprobiotics; probiotics.

Figure 1

Biogenic amine production of the L. lactis 11/19-B1 strain and other LABs for comparison. The L. lactis 11/19-B1 strain and E. faecalis did not produce any of the biogenic amines tested in this study. C: negative control; P1 and P2: genus Pediococcus isolated from miso; Ef: E. faecalis; Ec: E. coli; B1: L. lactis 11/19-B1.

Figure 2

Survival curves of the L. lactis 11/19-B1 strain and other LABs for comparison under simulated gastrointestinal tract conditions. Bars indicate the standard deviation. Circles: L. lactis 11/19-B1; squares: L. lactis JCM5805; triangles: B. lactis Bb-12; open symbols: SS (in saline); filed symbols: SM (in skim milk).