| Abstrakt: |
Lactic acid bacteria (LAB) strains are a natural part of our foods and environment. It has long been recognized to produce antimicrobial substances, used both for fermentation and the bio-preservation of food. Hence the importance of this work which focused on the study of the antagonistic effect of LAB strains isolated from fermented goat milk flavored with Phoenician juniper leaves stored in goatskin churn (Chekoua), against some microbial contaminants. Some technological properties of LAB strains were assessed and the antibacterial effect of lactic acid isolates was done using a spot test on agar. However, the antifungal effect was evaluated through the mycelial radial growth on agar and the biomass on broth culture. Out of seven isolated lactic acid strains, three (3) belong to Lactobacillus spp (Lb) and four (4) others to Streptococcus spp (S). The physiological and technological characteristics were different from one to another. S1, S2, S3, S4, and Lactobacillus plantarum (Lb1) strains have shown interesting technological properties (acidifying power, and proteolytic activity). On the one hand, all the lactic acid isolates were γ-hemolytic, and on the other hand, lactobacilli strains were resistant to a total of (6 to 7) antibiotics out of 12 tested antibiotics, i.e. 50 to 58%, while streptococci strains were susceptible to almost all the tested antibiotics except two antibiotics from the quinolones and sulfonamides class: pefloxacin and co-trimoxazole. The antimicrobial effect results indicate that S1 and S2 strains exhibited an antagonistic effect against the growth of bacterial contaminants, namely Staphylococcus aureus, Serratia ordorifera, and Entrobacter sakazakii isolated from goat milk. Lb1, S1, S2, S3, and S4 strains showed an antifungal effect with an inhibition rate ranging from 50 to 60%; 27.5 to 50% and 59.6 to 80.17% based on spore suspension, mycelial disc, and fungal biomass method, respectively. The antimicrobial effect was probably due to the synthesis of inhibitory substances, which constitutes a perspective for further research on both the characteristics of microflora, their identification as species and bioactive antimicrobial compounds, and the search for new and more effective LAB strains as a starter culture from traditional food products. [ABSTRACT FROM AUTHOR] |
