FUNCTIONAL FERMENTED BEVERAGES ENRICHED IN SELENO-AMINO ACIDS AND SELENO-NANOPARTICLES

FERNANDO GABRIEL MARTINEZ; GUSTAVO MORENO MARTIN; YOLANDA, MADRID; OMAR F. ORDOÑEZ; MICAELA PESCUMA; FERNANDA MOZZI

Congreso; XV CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE; 2020

XV CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE

Selenium (Se) is an essential micronutrient for humanhealth, which is found as selenocysteine (SeCys) in the active site of Se-dependentenzymes involved in the response to oxidative stress and in thyroid functions.The main inorganic Se forms, selenite and selenate are toxic. Some lactic acidbacteria (LAB) can reduce Se salts into seleno-nanoparticles (SeNPs) and seleno-aminoacids, which are non-toxic and highly bioavailable forms. In several Europeancountries, as well as in Argentina, Se intake is below the recommended dietary intake(RDI). Se-enrichment of foods is an attractive strategy to increase its ingestion.We aimed to formulate a fermented fruit juice-milk beverage (FJMB) bio-enrichedin Se. The fruit-origin strains Fructobacillustropaeoli CRL 2034 and Levilactobacillusbrevis CRL 2051 were grown with or without 5 mg/L of Se prior toco-inoculation (1% of each strain) in the FJMB and were incubated 14 h at 30 °C.The survival of the strains under storage conditions (6 °C, 52 days), and afterdigestion [using an in vitro gastrointestinalsystem (GIS)] was analyzed. The strains grew (up to 8.6 U log each) andacidified FJMB reaching a final pH of 4.6. Sugar metabolism and organic acidproduction were similar for control and selenized cells (RP-HPLC); while mannitolproduction by selenized cells of the Fructobacilluswas lower (0.18 ± 0.03) than control cells. The studied strains could notdegrade the proteins present in the FJMB (SDS-PAGE). Selenized cells increasedthe beverage total Se concentration (ICP-MS, 84.9 ± 4.5 μg/L) andbiotransformed selenite into SeCys (39.1 ± 0.4 μg/L) and SeMet (6.1 ± 0.1 μg/L)as detected by LC-ICP-MS. Moreover, SEM images of the fermented FJMB revealed thepresence of SeNPs attached to the cell surface of both strains. Interestingly, microbialresistance at the end of the shelf life was greater (between 0.5 and 0.7 U log)for selenized than non-selenized cells. However, no differences were observed inthe sugar and organic acid concentrations between treated and non-treated cellsand a lower (0.29±0.04 g/L) mannitol production was detected at 28 dayincubation by the treated strains. After GIS digestion, a decrease in the cellcounts of F. tropaeoli and L. brevis (1.60 and 0.80 U log,respectively) was observed. Interestingly, 64.3 ± 3.3 μg total Se/L partly asSeCys (25.8 ± 2.3 μg/L) and SeMet (2.4 ± 0.2 μg/L) were found in the FJMB supernatantafter intestinal digestion, highlighting the bioaccessibility of thesecompounds. Remarkably, 250 mL of the FJMB could cover 64% of the Se RDI (25 µg/day),from which 28% is composed by seleno-amino acids. Our results suggest that selenizedcells of F. tropaeoli CRL 2034 and L. brevis CRL 2051 could be used forformulating functional Se-enriched beverages to improve this micronutrientintake in humans.