CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Cell behaviour and accumulation of selenium by lactic acid bacteria
Autor/es:
L G RUIZ RODRIGUEZ; F G MARTINEZ; F MOZZI; M PESCUMA
Reunión:
Simposio; V Simposio Internacional de Bacterias Lacticas; 2016
Resumen:
The trace element Selenium (Se) is essential for human health; its deficiency is associated to viral infections, thyroid dysfunction, different types of cancer and aging. The Se content in food is scarce in Argentina and it has been reported as lower than those for other countries indicating a moderate status of this micronutrient content in our foods. Se health benefits depend on the form in which it is consumed; organic and elemental Se are less toxic and have increased bioavailability than inorganic Se. Some lactic acid bacteria (LAB) are able to accumulate and bio-transform Se into elemental and organic forms. The ability of LAB isolated from Argentinean fruits to grow in the presence of and to accumulate Se was studied in this work. Lactococcus lactis subsp. lactis CRL2009, Leuconostoc pseudomesenteroides CRL1997, Lactobacillus brevis 77, L. rhamnosus CRL2031, Enterococcus hirae 90, and Fructobacillus tropaeoli CRL2038 were grown in MRS supplemented with 5, 10, and 20 mg/L Na2SeO3 at 30 °C for 24 h. Cell growth (OD600, cfu/mL), pH, glucose concentration and organic acid production (HPLC), and Se accumulation (atomic absorption spectrophotometry) were determined. All strains were able to grow in the presence of Se and no significant differences were found when increasing the Se concentrations except for Lc. lactis CRL2009, which showed a decrease of 0.8 and 1.0 log U cell growth in the presence of 5 and 20 mg/L Se, respectively. Consistently, no differences in the acidifying capacity of the strains in the presence of Se was observed except for the strain Lc. Lactis CRL2009, which showed pH values 0,2 and 1,5 higher than the controls when grown in the presence of 5 and 20 mg/L of Se, respectively, after 24 h of incubation. Regarding glucose metabolism, Leuc. pseudomesenteroides CRL1997 and L. brevis 77 produced higher amounts of acetic acid (0.13 and 2.93 g/L, respectively) and less ethanol (2.3 and 1.2 g/L, respectively) in the presence of Se respect to the controls. The opposite behavior was observed for F. tropaeoli CRL2038, which produced less acetic acid (0.2 g/L) and more ethanol (1.3 g/L). Atomic absortion spectrophotometry studies, showed that LAB strains were able to accumulate between 1.7 and 39.3% of the added Se to the culture medium at 24 h incubation, being F. tropaeoli CRL2038 and Lc. lactis CRL2009 the strains which showed the highest amounts of intracellular Se (449 and 472 mg Se/kg cell, respectively). These strains could be interesting candidates for Se enrichment of LAB as an interesting tool for food supplementation to improve this micronutrient intake in humans.