Bacteriocins of lactic acid bacteria have been widely studied in recent years; however, there are relatively few studies that describe their chemical structure. This may be due to the many challenges associated with the purification of these antimicrobial peptides. This study was amid to isolate lactic Acid Bacteria (LAB) from meat in Jeddah - Saudi Arabia on (MRS) medium. Forty isolates of LAB showed antibacterial activities against indicator bacteria Gram positive bacteria S.aureus ATCC25923, and Gram negative bacteria E.coli ATCC25422, K.pneumonia ATCC700603, P.aeruginosa ATCC27583. Also antibacterial activities was screened by agar well diffusion method, results showed that ten out of 40 (25%) of the tested isolates have antibacterial activities against all indicator bacteria. The isolates of LAB with the highest antimicrobial effect were identified on the basis of its genetically sequencing. Results revealed that the M8 isolate have 96% identity with Leuconostoc mesentroides and was the highest bacteriocin producer. So it has been selected for the current investigation. The effect of different factors such as (inoculums concentrations, incubation temperature, incubation period, pH and aeration) on the production of bacteriocin was studied. The best condition for the production of highest amount of bacteriocin was incubation of static culture at 35°C for 24 hr and pH 6.2.
Key words: bacteriocin , Lactic Acid Bacteria, isolation, production