Biotransformation and accumulation of selenium by fructophilic lactic acid bacteria

FERNANDO GABRIEL MARTINEZ; MICAELA PESCUMA; FERNANDA MOZZI

Simposio; 2th International Symposium of Lactic Acid Bacteria; 2017

Biotransformation and accumulation of seleniumby fructophilic lactic acid bacteria FernandoG. Martínez, Micaela Pescuma, Fernanda MozziCentrode Referencia para Lactobacilos (CERELA)-CONICET. Chacabuco 145, 4000 SanMiguel de Tucuman, Argentina. fmozzi@cerela.org.ar Selenium(Se) is an essential trace element present in proteins as SeCys. Se isincorporated in humans through ingestion of plants, which are able toaccumulate it. Some lactic acid bacteria (LAB) can accumulate and biotransformSe into SeCys and synthesize nanoparticles. Fructobacilli are fructophilic LAB mainlyisolated from plant sources. In this work we aimed to study the ability of fruitorigin Fructobacillus strains toaccumulate and biotransform Se into organic forms and nanoparticles. Ninestrains of Fructobacillus isolatedfrom fig, custard apple and khaki were grown in thepresence of Na2SeO3. The amount of intracellular Se and SeCyswas determined by ICP-MS while the formation of Se nanoparticles was visualizedby SEM. The remaining Se in the supernatants was measured by the diaminonaphthalenemethod. Similar growth behavior was observed for all strains when 20 ppm Se wasadded in the medium compared to the control. The percentage of Se biotransformationwas between 41.3 and 83.1 %. F. tropaeoliCRL 2034, the strain which showed the highest Se accumulation values, could growin the presence of 200 ppm of Se although a decrease in its viability wasalready observed when adding 60 ppm Se (1 log U at 24 h incubation). As the alloweddaily Se concentration for human consumption is 5 ppm, this value was used infurther studies. ICP-MS results indicated that the Fructobacillus strain could accumulate 10 % of the added Se fromwhich 1.5% was SeCys. Moreover, the strain was able to produce sphericalnanoparticles and no effect on the cell morphology was observed. F. tropaeoli CRL 2034 could be used toproduce Se nanoparticles or Se-enriched fruit-based foods.