Screenings of Lactic Acid Bacteria Isolated from Dried Fruits and Study of Their Antibacterial Activity

Abstract

The objective of this study was enumeration, identification of lactic acid bacteria LAB from dried fruits and testing their antibacterial activity against different types of bacteria. Dilution method and cultivation in selective media was used for enumeration LAB, the isolates were identified by their physiological and biochemical characteristics and their antibacterial activity was performed by the agar well diffusion method. The results showed that thirty-seven isolates of LAB were isolated from tested samples, The isolates belonged to Lactococcus lactis subsp lactis (8), Lactococcus raffinolactis (6), Streptococcus thermophilus (6), Pediococcus acidilactici (3), Lactobacillus delbrueckii subsp. bulgaricus (2), Lactobacillus helveticus (3), Lactobacillus plantarum(4), Lactobacillus alimentarius (1), Lactobacillus brevis (2) and Lactobacillus fermentum(2).The results of antibacterial activity showed that seven CFSs of LAB had antibacterial activity against at least four strains tested. Lactobacillus fermentum had the best activity, they inhibited eight strains from sixteen tested strains, such as Streptococcus spp, Streptococcus sanguins, Staphylococcus epidermis, Staphylococcus aures, Proteus mirabilis, Hafnia alveie and Yersinia spp. In general, CFSs wewre active against the Gram positive more than Gram negative strains. MICs values were between 25 - 100 AU/ml.