Biokonzervačný potenciál kmeňov Lactococcus lactis izolovaných z ovčích hrudkových syrov
Antibacterial and antifungal activity of 20 wild lactococcal strains isolated from sheep cheeses against a microorganism indicator was examined. Lactococci were also tested for their ability to produce antimicrobial substances (lactic acid, hydrogen peroxide, biacetyl, carbon dioxide) in milk or broth.
The highest antibacterial activity was shown by Lactococcus lactis 10S4 and L. lactis 10S2 against Bacillus cereus (inhibition 14.68 and 13.65 %, respectively).
L. lactis 5S10 inhibited the growth of all the fungi indicators. The most sensitive fungi were Mucor rouxii and Rhizopus oryzae. Lactococci produced varying quantities of lactic acid. L. lactis 7S5 showed the highest final concentration of lactic acid (8.05 g/L) at 30 °C after 48-h incubation in milk. Hydrogen peroxide was produced by all of lactococcal strains except L. lactis 7S7 and 5S9. L. lactis 10S5 produced the highest amount of hydrogen peroxide (4.05 µg/mL). Six lactococci produced biacetyl and seven strains carbon dioxide.