Antilisterial activity of dromedary lactoferrin peptic hydrolysates

The aim of this study was to explore the antibacterial peptides derived from dromedary lactoferrin (LFc). The LFc was purified from colostrum using a batch procedure with a cation exchange chromatography support and was hydrolyzed with pepsin to generate peptic digest. This peptic digest was fractionated by cation exchange chromatography, and the antilisterial activity of LFc, peptic digest, and obtained fractions was investigated using the bioscreen method. The growth of Listeria innocua ATCC 33090 and LRGIA 01 strains was not inhibited by LFc and its hydrolysates. Two fractions of dromedary lactoferrin peptic hydrolysate were active against both strains. A tandem mass spectroscopy analysis revealed that the 2 active fractions comprised at least 227 different peptides. Among these peptides, 9 found in the first fraction had at least 50% similarity with 10 known antimicrobial peptides (following sequence alignments with the antimicrobial peptide database from the University of Nebraska Medical Center, Omaha). Whereas 9 of these peptides presented homology with honeybee, frog, or amphibian peptides, the 10th peptide, F₁₅₂SASCVPCVDGKEYPNLCQLCAGTGENKCACSSQEPYFGY₁₉₂ (specifically found in 1 separated fraction), exibited 54% homology with a synthetic antibacterial peptide (AP00481) derived from human lactoferrin named kaliocin-1. Similarly, the second fraction contained 1 peptide similar to lactoferrampin B, an antibacterial peptide derived from bovine milk. This result suggests that peptic hydrolysis of LFc releases more active antimicrobial peptides than their protein source and thus provides an opportunity for their potential use to improve food safety by inhibiting undesirable and spoilage bacteria.