title: Proteolytic and antimicrobial activity of lactic acid bacteria grown in goat milk.
abstract: We examined 62 strains and 21 trade starter cultures from the collection of LB Bulgaricum PLC for proteolytic and antimicrobial activity of lactic acid bacteria (LAB) grown in goat milk. The aim of this study was to investigate the fermentation of caseins, α-lactalbumin and β-lactoglobulin by LAB, using theo-phthaldialdehyde (OPA) spectrophotometric assay and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The proteolysis targeted mainly caseins, especially β-casein. Whey proteins were proteolyzed, essentially β-lactoglobulin. The proteolytic activity ofLactococcus lactisl598,Streptococcus thermophilust3D1, Dt1,Lactobacillus lactis1043 andL. delbrueckiisubsp.bulgaricusb38, b122 and b24 was notably high. The proteolysis process gave rise to medium-sized peptide populations. Most of the examined strains showed antimicrobial activity against some food pathogens, such asEscherichia coli,Staphylococcus aureus,Salmonella cholere enteridis,Listeria monocytogenes,Listeria innocuaandEnterobacter aerogenes. The most active producers of antimicrobial-active peptides were strains ofL. delbrueckiisubsp.bulgaricusandS. thermophilus, which are of practical importance. The starter cultures containing the examined species showed high proteolytic and antimicrobial activity in skimmed goat milk. The greatest antimicrobial activity of the cultures was detected againstE. aerogenes. The obtained results demonstrated the significant proteolytic potential of the examined strains in goat milk and their potential for application in the production of dairy products from goat's milk. The present results could be considered as the first data on the proteolytic capacity of strains and starter cultures in goat milk for the purposes of trade interest of LB Bulgaricum PLC.
authors.affiliation: R&D Center, LB Bulgaricum PLC , Sofia , Bulgaria.
authors.forename: Jivka
authors.initials: J
authors.lastname: Atanasova
authors.affiliation: Department of General and Applied Microbiology, Biological Faculty, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria.
authors.forename: Penka
authors.initials: P
authors.lastname: Moncheva
authors.affiliation: Department of General and Applied Microbiology, Biological Faculty, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria.
authors.forename: Iskra
authors.initials: I
authors.lastname: Ivanova
keywords: antimicrobial activity; goat milk; lactic acid bacteria; peptides; proteolytic activity