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 genera Lactococcus, Pediococcus, Lactobacillus, Weissella, and Enterococcus. 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 of Stenotrophomonas maltophilia, Pantoea agglomerans, Pseudomonas savastanoi, the food-borne Staphylococcus aureus, and Listeria monocytogenes was recorded. Antifungal activity evaluation showed that Botrytis cinerea was the most inhibited fungus followed by Penicillium expansum, Verticillium dahliae, and Aspergillus niger. Most of the active strains belonged to the genera Enterococcus and Weissella. 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.

No abstract

Four isolated lactic acid bacteria LAB strains Lactobacillus brevis, Lactobacillus plantarum, Pediococcus pentoseus, and Pediococcus acidilactici were selected and used to inoculate sourdough in order to reduce acrylamide content. After fermentation for 16 h, all of the inoculated sourdoughs showed lower pH values compared to the spontaneous sourdough. This acidification was accompanied by a significant (p<0.05) increase in the concentration of reducing sugars. The baked bread samples made with the tested LAB strains showed significantly reduced acrylamide content, in particular for the sample inoculated with P.acidilactici (5.64 µg/kg), compared to the bread sample prepared with baker's yeast (35.6 µg/kg). The resulting breads were also evaluated for several other quality parameters. The highest softness was registered for the breads obtained from the fermentation by P.acidilactici (2704 g). The different tested strains also influenced the color, the void fraction, and the cell density of the breads. The sensory evaluation indicated that the crust color, crumb aeration, as well as the salty and acidic tastes were not significantly affected by sourdough incorporation. However, breads made from LAB sourdoughs were more appreciated by the tasters. This study proved the suitability use of the selected P.acidilactici strain for industrial-scale bread production.