Isolation and identification of factors affecting antimicrobial compound production of Lactobacillus plantarum

Abstract

Eight strains of lactic acid bacteria were isolated from the traditional fermented foods such as handmade yoghurt, fermented pork roll, pinkle, kimchi, sour bamboo shoots and eggplants. The result of screening selected lactic acid bacteria SC01 which have high antagonistic activity and produce strong antibacteria compound against some indicator bacteria such as Salmonella, Staphylococcus aureus, Escherichia Coli, Listeria monocytogenes and Bacillus subtilis. The result of sequencing 16S rDNA showed the SC01 was Lactobacillus plantarum. Studying antibacterial compound production of L. plantarum SC01 on some different media revealed the best medium for L. plantarum SC01 was modified MRS broth. Studying influence of temperature, pH, NaCl concentration and MRS medium composition identified MRS OPTSC01 medium containing nitrogen sources (beef extract (10 g/l)), yeast extract (5 g/l), trypton (10 g/l)), carbon source (sucrose (20 g/l)), sodium acetate (5 g/l), K2HPO4 (4 g/l), ammonium citrate (2 g/l), MgSO4 (0.2 g/l), MnSO4 (0.05 g/l) and Tween 80 (1 ml/l), pH=6.0; temperature 37oC. On this optimal medium, the growth curve of L. plantarum SC01 was established to evaluate the production of antibacterial compound. The result indicated that L. plantarum SC01 grew strongly and produced highly antagonistic antibacterial compound at 28th hour. The research results is a prerequisite for the study of antimicrobial compounds extracted from L. plantarum to applications in food preservation and animal disease prevention.