Effect of lactic acid bacteria on mercury toxicokinetics

The capacity of two LAB strains to inhibit inorganic [Hg(II)] and organic (methyl-Hg; MeHg) mercury translocation through monolayers of co-cultures of NCM460 and HT29-MTX colonic cells was evaluated. Lactobacillus casei BL23 and Lactobacillus acidophilus ATCC4356 reduced the permeability of Hg(II) and MeHg from aqueous solutions through NCM460/HT29-MTX monolayers (20–94% reduction). However, assays using the bioaccessible (soluble) Hg fraction obtained by in vitro gastrointestinal digestion of Hg-contaminated swordfish only showed a reduction (42%) with the BL23 strain. In vivo experiments carried out in mice receiving an acute dose of Hg(II) or MeHg (0.5 mg/kg body weight/day) with or without lactobacilli resulted in significant decreases of the bioavailability of MeHg with both strains and increased excretion of Hg in feces after treatment with the lactobacilli. However, Hg(II) bioavailability or excretion was not affected. Hg accumulation in liver and kidney remained similar in LAB-treated or non-treated animals. This is the first study of the impact of LAB on Hg(II) and MeHg toxicokinetics and shows that some LAB strains have potential to diminish MeHg bioavailability. Furthermore, it has established the basis for new studies on the protective effect of LAB under conditions resembling subchronic and chronic Hg exposures.This work was supported by the Spanish Ministry of Science, Universities and Innovation (AGL2015-68920-R). Carlos Jadán Piedra received a Personnel Training Grant from SENESCYT (Ecuadorian Ministry of Higher Education, Science, Technology and Innovation) to carry out this study. Álvaro Crespo had a Contrato de Garantía Juvenil from the Spanish Government which was partially funded by the European Social Fund.Peer reviewe