Selection of Lactic Acid Bacteria Producing Antimicrobial Strain Such the Genus Lactococcus Isolated from Algerian Raw Goat's Milk

Abstract

Lactic acid bacteria are known for their ability to produce inhibitory substances against unwanted germs involved in food poisoning such as Listeria innocua. Species of lactic acid bacteria can inhibit harmful germs subject of this work. techniques confrontation on solid medium and the effect of the substance on the growth of Listeria innocua were performed. The experience was conducted bacterial antagonism in the solid medium by the method of double layer and method of wells, the whole experience was packaged in a buffered medium in order to eliminate the effect of acidity . 7 strains that isolates gave an antagonistic action against Listeria innocua. The strain of Lactococcus lactis (8b), isolated from raw goat's milk showed an anti-listeria in vitro and was selected because of its ability to inhibit as Staphylococcus aureus. With a diameter of 15mm, the action of proteolytic enzymes, trypsin, chymotrypsin is shown that the substance was protein in nature, the kinetics of growth in milk medium showed that the number of St. aureus after 24 h of incubation was reduced to 7.68 log cfu in mixed culture with strain 8b which was comparable to the control of 9.14 log cfu, which signifies that the survival rate was 3.4%, the phenotypic (biochemical and physiological) and molecular-based ADNr16Ss showed that the strain is Enterococcus faecium, duran, hirae. The sequencing results showed that Leuconostoc mesenteroides and Enterococcus faecium have summers dominant anti-Listeria species in milk samples from Algerian goat. Isolates had the potential of multiple bacteriocin production and do not have some important virulence. Importance and impact of the study: The Enterococci in milk in this region of western Algeria could be partly responsible for the safety of cheese and could be useful for the production of anti-Listeria cultures protection. The purpose of the study: Our study's main objective is the selection ,and study phenotypic and molecular lactic acid bacteria from Lactococcus genus possessing biotech traits such as the production of new inhibitory substance and the study of the interaction of Listeria innocua screw opinion and St. aureus that both methods were used, a traditional approach based on morphological and biochemical studies of different cultural characteristics and a method of direct molecular amplification of bacterial DNA using PCR / RAPD colony on having targeted DNA fragment 16S lactic acid bacteria using the two primers universal: 20F (5'AGAGTTTGATCATGGCTCAG-3 '). 1500R (5'-GGTTACCTTGTTACGACTT-3 ') and two specific primers OPA-3 (5'-AGTCAGCCAC - 3') and OPH 3 (5'-AGACGTCCAC-3 ') (Bioprobe, France).