Formulation of a selenized fermented drink with strains of Lactobacillus brevis and Fructobacillus tropaeoli

CUENCAS BARRIENTOS EMILIA; MARTINEZ FERNANDO; FERNANDA MOZZI; MICAELA PESCUMA

Congreso; VII CICYTAC; 2018

Formulation of a selenized fermented drink with strains of Lactobacillus brevisand Fructobacillus tropaeoliCuencas Barrientos E (1), Martínez F G (1), Mozzi F (1), Pescuma M (1)(1) Centro de Referencia para Lactobacilos (CERELA-CONICET), Chacabuco145, San Miguel de Tucumán, Argentina.fmartinez@cerela.org.arSelenium (Se), which is present as SeCys in seleno-proteins, is involved incancer prevention, thyroid functioning, and pathogen inhibition. Se isincorporated in the diet through Se-containing foods. Lactic acid bacteria (LAB)are commonly used in the food industry due to their capacity to increase foodsafety and stability. Moreover, some LAB may biotransform inorganic Se (toxic)into organic forms such as Se-amino acids and Se-nanoparticles (SeNPs). Weaimed to formulate a fermented milk/fruit juice beverage using strains thatbiotransform and accumulate Se intracellularly. Lactobacillus brevis 73 andFructobacillus tropaeoli 108 were grown in MRS with or without selenite (5mg/L), cells were washed and used for inoculating a milk/mango-orange fruitmixture (4:1, v/v) at 30 °C for 14 h. Microbial growth (cfu/ml), sugar, organicacids and ethanol concentrations (HPLC) and protein degradation (SDS-PAGE)were determined at the end of fermentation. Selenium content in the drink wasdetermined by atomic abortion, while the presence of SeNPs was analyzed byscanning electronic microscopy (SEM). The survival of the strains under storageconditions (4°C, 28 days) and after digestion (using an in vitro digestive system)was also determined. Selenized and non-selenized cells grew well (between 9.2and 9.8 cfu/ml at 14 h) and acidified the matrix (̴ 0.8 U) at a similar extent. L.brevis 73 fermented glucose (2.6-1.9 g/L, control and selenized cells,respectively) in a higher extent than fructose (0.7-0.9) and produced lactic acid(2.0-1.7 g/L). Both control and selenized cells of F. tropaeoli 108 consumedmainly fructose (4.2-4.5 g/L) and produced mannitol (4.6-4.7 g/L) while glucosewas consumed in a lesser extent releasing lactic and acetic acid (1.5-1.1 and1.0 g/L, respectively). The studied strains could not degrade the proteinspresent in the milk/fruit mixture. SEM imagines of the fermented drinks revealedthe presence of SeNPs attached to the cell surface of the selenized L. brevisand F. tropaeoli strains; however, Se was detected only in the supernatant ofthe L. brevis selenized fermented drink at a concentration of 100 μg/L. Understorage conditions, a decrease of 1 log U cfu/ml was observed for the selenizedL. brevis strain after 28 days incubation while no effect on cell viability wasobserved for the non-selenized strain. Inversely, a decrease in the cell counts(0.7 U log cfu/ml) of control and selenized cells of F. tropaeoli 108 wasobserved after 14 days at 4°C. L. brevis 73 was able to survive to the in vitrogastrointestinal tract while a drastic decrease (2.6-0.8 U log cfu/ml) in F.tropaeoli 108 cell count was observed; the selenized cells being more resistantthan the control ones. These strains could be used in the production of novelSe-bioenriched fermented drinks.