Assessment of the Antibacterial Potential and Safety Profile of Lactic Acid Bacteria Strains Isolated from Algerian Raw Milk

Background: Raw milk harbors most lactic acid bacteria. Research in this field is a hot topic with the aim of using them for probiotic and/or technological applications. Methods: Lactic acid bacteria were isolated on MRS and M17 media. Antibacterial activity was tested by the direct method based on spots against four food-borne pathogens. Isolates demonstrating high antibiosis activity were selected following a statistical analysis (Two-way-ANOVA) and identified by MALDI-TOF MS. The safety profile was assessed by sensitivity to antibiotics, hemolytic activity, the ability to produce gelatinase and DNase and finally, the aptitude of lactic strains to form biogenic amines. Result: A total of 172 strains were isolated, of which 103 were presumed to be lactic acid bacteria. The results of the antibacterial activity demonstrated that 82 strains exerted an antagonistic effect against all reference strains and 12 of these showed significant antibiosis activity. Selected strains were identified as Lactococcus lactis ssp lactis (50%) and Enterococcus faecium (50%). All strains of Lactococcus lactis ssp lactis (LMMDR33, LMMDR06, LMMDR22, LMMDR26, LMMDR05 and LMMDR23) and strains LMMDR27, LMMDR16 and LVBBR13 of Enterococcus faecium demonstrated a good safety profile. They were retained for valorization.