Diversity and Antimicrobial Properties of Lactic Acid Bacteria Isolated from Rhizosphere of Olive Trees and Desert Truffles of Tunisia

Abstract

A total of 119 lactic acid bacteria (LAB) were isolated, by culture-dependant method, from rhizosphere samples of olive trees and desert truffles and evaluated for different biotechnological properties. Using the variability of the intergenic spacer 16S-23S and 16S rRNA gene sequences, the isolates were identified as the generaLactococcus, Pediococcus, Lactobacillus, Weissella,andEnterococcus. All the strains showed proteolytic activity with variable rates 42% were EPS producers, while only 10% showed the ability to grow in 9% NaCl. In addition, a low rate of antibiotic resistance was detected among rhizospheric enterococci. Furthermore, a strong antibacterial activity against plant and/or pathogenic bacteria ofStenotrophomonas maltophilia, Pantoea agglomerans, Pseudomonas savastanoi, the food-borneStaphylococcus aureus,andListeria monocytogeneswas recorded. Antifungal activity evaluation showed thatBotrytis cinereawas the most inhibited fungus followed byPenicillium expansum, Verticillium dahliae,andAspergillus niger. Most of the active strains belonged to the generaEnterococcusandWeissella. This study led to suggest that environmental-derived LAB strains could be selected for technological application to control pathogenic bacteria and to protect food safety from postharvest deleterious microbiota.