Use of Lactococcus lactis Subsp. Lactis Strains to Inhibit the Development of Pathogens

摘要

Bovine mastitis affects the udder health and thus causing significanteconomic losses. Probiotic products based on the use of lactic acid bacteria(LAB) to limit pathogens multiplication and pre-infection risks can be aninteresting alternative to post infection allopathic treatment with antibiotics.Lactococcus lactis is one of the most important bacteria used in dairy technology. In thiswork, a total of 21 Lactococcus lactis subsp. Lactis strains, 20 from goat milk whey and onestrain from cow milk were used to evaluate their antibacterial activity againstfour pathogenic germs responsible for mastitis: Escherichia coli , Staphylococcus aureus , Streptococcus uberis and Streptococcus agalactiae . Thenisin-producing cow milk strain was active against St . uberis and Str . Agalactiae using the well diffusion method. For the strains isolated from goat milkwhey, no antimicrobial effect was observed against these pathogens. However, adifferent approach based on the growth of pathogenic bacteria interacting withthe Lactococcus lactis strains in a minimum medium was used to study the barrier effect of LAB.The Lactococcus lactis strains S1 and S2 from goat milk whey depleted the growth of Sa . aureus , St . uberis and E . coli during 8 h and stopped the development of St . agalactiae .