Investigating the effects of conventional and unconventional edible parts of red beet (Beta vulgaris L.) on target bacterial groups and metabolic activity of human colonic microbiota to produce novel and sustainable prebiotic ingredients.

This study investigated the effects of freeze-dried red beet root (FDBR) and freeze-dried red beet stem and leaves (FDBSL) on target bacterial groups and metabolic activity of human colonic microbiota in vitro. The capability of FDBR and FDBSL to cause alterations in the relative abundance of different selected bacterial groups found as part of human intestinal microbiota, as well as in pH values, sugar, short-chain fatty acid, phenolic compounds, and antioxidant capacity were evaluated during 48 h of in vitro colonic fermentation. FDBR and FDBSL were submitted to simulated gastrointestinal digestion and freeze-dried prior to use in colonic fermentation. FDBR and FDBSL overall increased the relative abundance of Lactobacillus spp./Enterococcus spp. (3.64-7.60%) and Bifidobacterium spp. (2.76-5.78%) and decreased the relative abundance of Bacteroides spp./Prevotella spp. (9.56-4.18%), Clostridium histolyticum (1.62-1.15%), and Eubacterium rectale/Clostridium coccoides (2.33-1.49%) during 48 h of colonic fermentation. FDBR and FDBSL had high positive prebiotic indexes (>3.61) during colonic fermentation, indicating selective stimulatory effects on beneficial intestinal bacterial groups. FDBR and FDBSL increased the metabolic activity of human colonic microbiota, evidenced by decreased pH, sugar consumption, short-chain fatty acid production, alterations in phenolic compound contents, and maintenance of high antioxidant capacity during colonic fermentation. The results indicate that FDBR and FDBSL could induce beneficial alterations in the composition and metabolic activity of human intestinal microbiota, as well as that conventional and unconventional red beet edible parts are candidates to use as novel and sustainable prebiotic ingredients.

Dynamics of physiological responses of potentially probiotic fruit-derived Limosilactobacillus fermentum in apple and orange juices during refrigeration storage and exposure to simulated gastrointestinal conditions.

This study evaluated the dynamics of the physiological responses of potentially probiotic fruit-derived Limosilactobacillus fermentum 139 and L. fermentum 263 in apple and orange juice during 28 days of refrigeration storage (4 °C) and when submitted to simulated gastrointestinal conditions. Physiological responses were measured with multiparametric flow cytometry using propidium iodide (PI), carboxyfluorescein diacetate (cFDA) and bis-1,3-dibutylbarbutiric acid (BOX). Viable counts were enumerated with plate count. L. fermentum strains had sizes of > 30% of cell subpopulations with non-permeabilized membrane and enzymatic activities (viable cells, PI-CFDA +) in apple and orange juices during storage and viable counts of > 6 log CFU ml-1. Sizes of cell subpopulations with permeabilized membrane without enzymatic activity (dead cells, PI + cFDA-) were low (< 15%) in apple and orange juices during storage. Sizes of cell subpopulations with non-permeabilized and depolarized membrane (PI-BOX +) were decreased (14%) on day 28 of storage. The sizes of permeabilized and depolarized membrane cell (PI + BOX-) subpopulations were variable among the examined strains in juices during storage. Both strains maintained high PI-cFDA + cell subpopulation sizes (> 35%) after exposure to ileum condition and viable counts of ≥ 5 log CFU/mL. PI-BOX + cell subpopulation sizes were low (< 13%) after exposure to ileum condition. L. fermentum 139 and L. fermentum 263 are capable of maintaining a high population of physiologically active and functional cells in apple and orange juice during 28 days of refrigeration storage and when exposed to gastrointestinal conditions.

Selection of lactic acid bacteria with promising probiotic aptitudes from fruit and ability to survive in different food matrices.

Lactic acid bacteria (LAB) are among the most prevalent microorganisms forming the autochthonous microbiota of fruit. This study aimed to select LAB isolates with probiotic aptitudes from apple, banana, grape, and orange through evaluation of in vitro safety, technological, and functional-related properties. The ability of most promising selected isolates to survive in commercial apple and orange juice, meat stew, vegetable puree, and UHT milk during 28 days of refrigeration storage was evaluated. Ninety-three isolates identified preliminarily as LAB were recovered from fruit and 66 of these isolates passed safety tests. Most of these isolates were pre-identified as belonging to Lactobacillus or Enterococcus genus based on MALDI-ToF MS profiling. These 66 isolates were categorized into three homogeneous groups based on a preliminary cluster analysis run with data from experiments to measure technological characteristics. Nine LAB isolates were selected as the most promising for probiotic use based on a principal component analysis run with data from experiments to measure probiotic-related properties. Four of these isolates were sensitive to different antibiotics and identified (16S-rRNA gene sequencing) as Lactobacillus brevis (recently reclassified as L. brevis) or Lactobacillus spp. These 4 selected isolates had high viable counts and high percentages of physiologically active cells in apple and orange juice, beef stew, vegetable puree, and UHT milk during refrigeration storage. The results showed that apple, banana, orange, and grape are potential sources of LAB with aptitudes to be exploited for a possible probiotic use and distinguished abilities to survive in different food matrices.