SelA and SelD genes involved in selenium absorption metabolism in lactic acid bacteria isolated from Mexican cheeses

Eight selenium-resistant bacteria were isolated from Mexican cheeses. Isolates were identified as Enterococcus faecalis (5), Enterococcus faecium (1), Leuconostoc citreum (1) and Lactobacillus futsaii (1) by 16S rRNA gene sequence analyses. Each isolate was cultured in presence of sodium selenite. Lactobacillus citreum and Lb. futsaii showed capacity to grow with 200 mg L?1 sodium selenite whereas the strains identified as Enterococcus spp. could grow at 600 mg L?1. Two genes (SelA and SelD) involved in the selenium traits were detected in the eight isolated strains. Biomass obtained from media enriched with sodium selenite turned into reddish colour, implying selenium reduction and bioaccumulation. Both findings reflected a high possibility that these strains have the capacity to incorporate inorganic selenium into proteins. All these bacteria may be exploited for biotransformation of inorganic selenium and as a potential dietary supplement of nontoxic selenium in food products.