ANTIMICROBIAL PEPTIDES GENERATED BY proteolysis of b-LACTOGLOBULIN using Lactobacillus STRAINS

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

Tucuman, Argentina

Simposio; III International Symposium on Lactic Acid Bacteria; 2009

Beta-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 L. delbrueckii subsp. bulgaricus CRL 656) strains to hydrolyze and to release antimicrobial peptides from BLG. These strains hydrolyzed BLG in a range of 48 to 52%. The release of antimicrobial peptides 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 obtained from the three Lactobacillus strains was used against the indicator strains. However, the Tricine SDS-PAGE of BLG-hydrolysate from L. delbrueckii subsp. bulgaricus CRL 656showed a 4 kDa peptide with activity against Listeria innocua 7. The RP-HPLC purified fractions of this BLG hydrolysate showed two peaks with antimicrobial activity eluting at 17 and 25 min. These data suggest that electrostatic interactions might interfere in the determination of the antimicrobial activity of the BLG-hydrolysate when they are used without purification. L. delbrueckii subsp. bulgaricus CRL 656 could be used as starter culture for the manufacture of functional dairy products not only for its contribution to health and nutrition improvement but also for providing peptides with antimicrobial properties.