Probiotic potential and biochemical and technological properties of Lactococcus lactis ssp. lactis strains isolated from raw milk and kefir grains

摘要

Lactococcus lactis ssp. lactis is one of the most importantstarter bacteria used in dairy technology andit is of great economic importance because of its usein the production of dairy products, including cheese,butter, cream, and fermented milks. Numerous studieshave evaluated the biochemical and probiotic propertiesof lactococci; however, limited studies on the probioticcharacteristics of lactococci were conducted usingstrains originating from raw milk and dairy products.Characterizing the probiotic properties of strains isolatedfrom raw milk and fermented milk products isimportant in terms of selecting starter culture strainsfor the production of functional dairy products. In thisstudy, biochemical properties (including antibiotic sensitivity,lipolytic activity, amino acid decarboxylation,antioxidant activity) and probiotic properties (includingantimicrobial activity, growth in the presence ofbile salts, bile salts deconjugation, and hydrophobicity)of 14 Lactococcus lactis strains isolated from raw milkand kefir grains were investigated. Strains originatingfrom kefir grains had better characteristics in termsof antimicrobial activity and bile salt deconjugation,whereas strains from raw milk had better hydrophobicityand antioxidant activity characteristics. None of thestrains were able to grow in the presence of bile salt anddid not show amino acid decarboxylation or lipolyticactivities. Biochemical and probiotic properties of L.lactis strains varied depending on the strain and someof these strains could be used as functional culturesdepending on their properties. However, these strainsdid not possess all of the properties required to meetthe definition of a probiotic.