Comparative analysis of the effect of Ca and Mg ions on antibacterial activity of lactic acid bacteria isolates and their associations depending on cultivation conditions

Abstract The effects of divalent cations of Ca and Mg on antibacterial activity of lactic acid bacteria (LAB) isolates, as well as their different associations were studied. Most LAB strains and associations revealed significant inhibitory effects in MRS against Gram-positive and Gram-negative test-organisms at different Ca2+ and Mg2+ concentrations (determined specifically for each LAB strain and each association). Some LAB strains and communities inhibited the growth of pathogenic test-organisms depending on both ions concentrations and cultivation conditions. Interestingly, the presence of Mg ions in medium significantly decreased the antimicrobial activity of LAB communities against pathogenic test-organisms; on the other hand, the combined mixture of ions essentially increased the inhibitory effect in case of time-spaced cultivation. In contrast, the inhibitory effects of many associations were significantly increased at the presence of Mg2+ and especially ions combination in case of simultaneous cultivation. The addition of ions combination didn’t affect antibacterial activity of LAB isolates. The results allow us to conclude that Ca and Mg ions had inducible effects on antibacterial activity in case of simultaneous cultivation. This probably can be prospective for creation of new antimicrobial preparations and their possible application

Antifungal activity of lactobacilli isolated from Armenian dairy products: an effective strain and its probable nature

Abstract Different strains of lactobacilli isolated from Armenian dairy products (matsoun, sour cream and different types of cheeses), were studied for antifungal activity. Lactobacillus rhamnosus MDC 9661 strain was shown to have inhibitory activity against Penicillium aurantioviolaceum and Mucor plumbeus growth. Bacterial cell-free supernatant didn’t show antifungal activity. The L. rhamnosus antifungal activity was stable to the wide range of pH from 3 to 10. This activity was high after treatment with both low temperature (− 30 °C) and lysozyme and with ultrasound. However, it was sensitive to high temperature from 45 to 80 °C and proteolytic enzymes. The results suggest the proteinaceous nature of L. rhamnosus antifungal activity associated with bacterial cell wall. L. rhamnosus MDC 9661 could be recommended as a starter for production of dairy products, functional food and preserving strain in food production

In Silico Probiogenomic Characterization of <i>Lactobacillus delbrueckii</i> subsp. <i>lactis</i> A4 Strain Isolated from an Armenian Honeybee Gut

A Lactobacillus delbrueckii ssp. lactis strain named A4, isolated from the gut of an Armenian honeybee, was subjected to a probiogenomic characterization because of its unusual origin. A whole-genome sequencing was performed, and the bioinformatic analysis of its genome revealed a reduction in the genome size and the number of the genes—a process typical for the adaptation to endosymbiotic conditions. Further analysis of the genome revealed that Lactobacillus delbrueckii ssp. lactis strain named A4 could play the role of a probiotic endosymbiont because of the presence of intact genetic sequences determining antioxidant properties, exopolysaccharides synthesis, adhesion properties, and biofilm formation, as well as an antagonistic activity against some pathogens which is not due to pH or bacteriocins production. Additionally, the genomic analysis revealed significant potential for stress tolerance, such as extreme pH, osmotic stress, and high temperature. To our knowledge, this is the first report of a potentially endosymbiotic Lactobacillus delbrueckii ssp. lactis strain adapted to and playing beneficial roles for its host

Potential use of lactic acid bacteria for reduction of allergenicity and for longer conservation of fermented foods

The interest of consumers for diverse fermented foods has increased in recent years thanks to the positive perception of their impact on consumer health considered as beneficial. Hence, there is an evident need for search of novel ways and for new food preservation agents of natural origins. In this aspect, lactic acid bacteria are very good candidates. It should be highlighted also that the onset of food allergies is rising significantly in recent years. The reduction of the immunoreactivity of food proteins could be achieved thanks to pre-prandial proteolysis occurring in fermented dairy (and other food) systems changing the allergen presentation or cleaving the allergenic protein epitopes, and produce hypoallergenic products.Fil: El-Ghaish, Shady. Institut National de la Recherche Agronomique; FranciaFil: Ahmadova, Aynur. Institut National de la Recherche Agronomique; FranciaFil: Hadji-Sfaxi, Imen. Institut National de la Recherche Agronomique; FranciaFil: El Merchefi, Kamel Eddine. Institut National de la Recherche Agronomique; Francia. Université d’Oran. Département de biologie. Laboratoire de Physiologie de la Nutrition et sécurité Alimentaire; ArgeliaFil: Bazukyan, Inga. Yerevan State University. Faculty of Biology; ArmeniaFil: Choiset, Yvan. Institut National de la Recherche Agronomique; FranciaFil: Rabesona, Hanitra. Institut National de la Recherche Agronomique; FranciaFil: Sitohy, Mahmoud. Institut National de la Recherche Agronomique; Francia. Zagazig University. Faculty of Agriculture. Biochemistry Department; EgiptoFil: Popov, Yuri G.. Yerevan State University. Faculty of Biology; ArmeniaFil: Kuliev, Akif A.. Baku State University. Biotechnical and Biochemistry Chair; AzerbaiyánFil: Mozzi, Fernanda Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Chobert, Jean-Marc. Institut National de la Recherche Agronomique; FranciaFil: Haertle, Thomas. Institut National de la Recherche Agronomique; Franci