Identification, Characterization and Genetic Improvement of Bacteriocin Producing Lactic Acid Bacteria

Abstract

Background and Objective: Bacteriocin produced by lactic acid bacteria has received more scientific attention, this is due to its ability to inhibit wide range of spoilage and pathogenic microorganisms and their potential usefulness as natural substitute for chemical food preservatives. The aim of the present study isolation, identification and improvement of Lactic Acid Bacteria (LAB) that produce bacteriocin from different traditional dairy products in Egypt. Methodology: Isolation and identification of LAB isolates based on morphological, biochemical and molecular 16S rDNA gene. To improve LAB bacteriocin production broth and filter mating techniques were used. The RAPD were used to confirm transconjugants. Results: Three bacterial isolates showed a high bacteriocin activity and named (I 1 , I 2 and I 3 ). The three bacterial isolate were Gram positive, cocci, asporogenous, non-motile and negative to catalase and oxidase. The biochemical identification using API kit indicated that isolates I 1 , I 2 were related to genus Enterococcus while isolate (I 3 ) was related to genus Pediococcus (94.4 and 99.5%) respectively. On the other hand, 16S rDNA sequencing showed 99% homology with Enterococcus faecium and 97% homology of I 3 with Pediococcus pentosaceus. All sequences were deposited in the GenBank nucleotide databases under accession number LC063691.1, LC063692.1 and LC063861.1. Genetic improvement of selected bacterial isolates were carried out using two different techniques of conjugation, filter and broth mating techniques. The transconjugation frequencies of the filter mating technique was higher than (4.610G 5 ) the broth mating technique (2.410G 5 ). The genetic variability among the transconjugants lines were tested using RAPD analysis and showed 8.25% polymorphism percentages for donor, recipient and tranconjugants lines. Conclusion: Results concluded that three bacteriocin producing LAB isolates Enterococcus faecium (I 1 -I 2 ) and Pediococcus pentosaceus (I 3 ) with probiotic properties could be used in wide range of different industrial application.