Antimicrobial peptides generated by proteolysis of beta-lactoglobulin using Lactobacillus strains

M. PESCUMA; L. SAAVEDRA; E. M. HÉBERT; F. MOZZI; G. FONT DE VALDEZ

Simposio; III Simposio Internacional de Bacterias Lácticas. II Encuentro RED BAL Argentina; 2009

β-lactoglobulin (BLG), the major bovine whey protein, contains bioactive peptides encrypted within the primary sequence showing antihypertensive, opioid, immunomodulating, antithrombotic, antimicrobial, mineral-binding and hypocholesterolemic activities. Certain lactic acid bacteria are able to hydrolyze BLG generating several peptides with biological activity. The aim of this work was to evaluate the ability of three Lactobacillus (L. acidophilus CRL 636, L. delbrueckii subsp. bulgaricus CRL 454 and CRL 656) strains to hydrolyze and release antimicrobial peptides from BLG. The analyzed strains hydrolyzed BLG in a range of 48 and 52%. The release of antimicrobial peptides by Lactobacillus strains was assessed by the plate diffusion assay; using Listeria innocua, Salmonella enterica and Staphylococcus aureus as indicator strains. No antimicrobial activity was detected when the BLG-hydrolysates from the three Lactobacillus strains was used against all indicator strains. However, the Tricine SDS-PAGE of BLG-hydrolysate from L. delbrueckii subsp. bulgaricus CRL 656 showed a 4 kDa peptide with activity against Listeria innocua 7. The RP-HPLC purified fractions of this BLG hydrolysate showed two peaks eluting at 17 and 25 min with antimicrobial activity. These data suggested that electrostatic interactions might interfere in the determination of the antimicrobial activity present in the BLG-hydrolysate without purification. L. delbrueckii subsp. bulgaricus CRL 656 could be used as a starter culture for the manufacture of functional milk products not only for its contribution to improve health and nutrition but also to provide peptides with antimicrobial properties.