Evaluación de las etapas y los factores que influyen en la solubilización de mercurio y selenio durante la digestión gastrointestinal de productos pesqueros

[ES] Los peces predadores tienden a acumular altos niveles de mercurio (Hg). Por otro lado, estos productos alimentarios son ricos en selenio (Se), elemento que puede contrarrestar los efectos tóxicos de Hg. El objetivo del presente estudio ha sido evaluar la bioaccesibilidad (fracción del contaminante que solubiliza desde el alimento durante la digestión gastrointestinal) del Hg y Se en pez espada cocinado, e identificar aquellos parámetros de la digestión (pH, concentración de pepsina, etapa de la digestión) que pueden influir en la misma. Las concentraciones de mercurio en las muestras analizadas oscilan entre 0,23 y 2,82 mg/kg peso húmedo (ph). La bioaccesibilidad del Hg varía entre un 15 y un 85%, siendo el rango de concentraciones en el bioaccesible muy variable (0,21-1,07 mg/kg ph). Las concentraciones de Se oscilan entre 0,46 y 0,98 mg/kg ph, con una bioaccesibilidad en general mayor que la de Hg y menos variable (63-100%; 0,41-0,51 mg/kg ph). En cuanto a los parámetros que influyen en la solubilización de estos elementos traza a su paso por el tracto gastrointestinal, se pone de manifiesto que la totalidad de la solubilización se produce en la etapa gástrica. Dentro de la etapa gástrica, los pHs ácidos (2-3) y el aumento de la concentración de pepsina suponen una mayor bioaccesibilidad, especialmente para el Hg. El presente estudio muestra que la consideración de la bioaccesibilidad en lugar de la concentración de Hg en el producto fresco supone una disminución de la exposición al tóxico, y por tanto un menor riesgo asociado a la ingesta de estos productos. También se pone de manifiesto que el estudio de la bioaccesibilidad de Hg y Se debe contemplar aquellos parámetros que se modifican durante la ingesta de alimentos y que como el pH y la pepsina son determinantes.[CA] Els peixos predadors tendeixen a acumular alts nivells de mercuri (Hg). D'altra banda, aquests productes alimentaris són rics en seleni (Se), element que pot contrarestar els efectes tòxics del Hg. L'objectiu del present estudi ha estat avaluar la bioaccessibilitat (fracció del contaminant que es solubilitza a partir de la seva matriu durant la digestió gastrointestinal) del Hg i Se en peix espasa cuinat, i identificar aquells paràmetres de la digestió gastrointestinal (pH, concentració de pepsina, etapa de la digestió) que poden influir en la mateixa. Les concentracions de mercuri en les mostres analitzades oscil·len entre 0,23 i 2,82 mg/kg pes humit (ph). La bioaccessibilitat del Hg varia entre un 15 i un 85%, sent el rang de concentracions en el bioaccesible molt variable (0,21- 1,07 mg/kg ph). Les concentracions de Se oscil·len entre 0,46 i 0,98 mg/kg ph, amb una bioaccessibilitat en general major que la de Hg i menys variable (63- 100%, 0,41-0,51 mg/kg ph). Quant als paràmetres que influeixen en la solubilització d'aquests elements traça al seu pas pel tracte gastrointestinal, es posa de manifest que la totalitat de la solubilització es produeix en l'etapa gàstrica. Dins de l'etapa gàstrica els pHs àcids (2-3) i l'augment de la concentració de pepsina suposen una major bioaccessibilitat, especialment pel Hg. El present estudi mostra que la consideració de la bioaccessibilitat en lloc de la concentració de Hg en el producte fresc suposa una disminució de l'exposició al tòxic, i per tant un menor risc associat a la ingesta d'aquests productes. També es posa de manifest que l'estudi de la bioaccessibilitat de Hg i Se ha de contemplar aquells paràmetres que es modifiquen durant la ingesta d'aliments i que com el pH i la pepsina són determinants.[EN] Predatory fish tend to accumulate high levels of mercury (Hg). Additionally, selenium (Se) present in these food products may counteract the toxic effects of Hg. The aim of the present study was to evaluate Hg and Se bioaccessibility (the contaminant fraction that solubilises from its matrix during gastrointestinal digestion) in cooked swordfish and to determine the influence of certain parameters of the gastrointestinal digestion (pH, pepsin concentration, stage of digestion) on Hg and Se bioaccessibility. The concentrations of Hg in cooked swordfish range between 0,23 and 2,82 mg/kg wet weight (ww). The bioaccessibility varies widely (15-85%), with concentrations in the bioaccessible fraction ranging from 0,21 to1,07 mg/kg ww. The concentrations of Se vary between 0,46 and 0,98 mg/kg ww, being the bioaccessiblity greater and less variable than that observed for Hg (63-100%; 0,41-0,51 mg/kg ph). The study of the influence of the parameters of the gastrointestinal digestion evidences that the whole solubilisation occurs in the gastric stage. In this gastric step, the acidic pHs (2-3) and the increase of the concentration of pepsin bring about an increases of the bioaccessibility, especially for Hg.Jadan Piedra, CA. (2012). Evaluación de las etapas y los factores que influyen en la solubilización de mercurio y selenio durante la digestión gastrointestinal de productos pesqueros. http://hdl.handle.net/10251/28130.Archivo delegad

Estrategias dietéticas para disminuir la biodisponibilidad de mercurio desde alimentos

Mercury (Hg) is a toxic metal widely distributed in the environment. The main route of exposure for humans is the diet, where it is presented in inorganic form [Hg(II)] or as methylmercury (CH3Hg). Seafood products, especially large marine predators, and mushrooms are the foods with the highest concentrations of this metal. The need to reduce Hg exposure of the population, especially those living in contaminated areas or those in which seafood products are an important basis of their diets, is a priority. However, it is not an easy task to avoid food contamination or to eliminate the contaminant prior to its consumption. It is therefore necessary to search for alternative ways to reduce exposure to Hg without eliminating from the diet these food products with a high nutritional value. One of these possible ways of action is to reduce selectively the arrival of Hg into the bloodstream after oral intake, without compromising the arrival of other essential elements and using for that purpose compounds whose food safety have been proven. This has been the main objective of this PhD thesis. An initial characterization of the bioaccessible fraction of foods with high Hg contents was carried out to determine the risk associated with their intake. The data show that the amount of Hg that is released during the digestion of the food is lower than the initial content of Hg in the sample and that it is especially affected by the gastric pH and, in the case of seafood products, also by the pepsin and pancreatic lipase concentrations. The evaluation of the molar ratio selenium (Se)/Hg shows that in the bioaccessible fractions, there is usually a molar excess of Se, which according to some studies indicates a lower risk associated to the exposure. Thus, although a significant proportion of these matrices exceed the maximum level for Hg and their intake would exceed the recommended weekly intake, the associated risk may not be so high if, as it has observed in vitro, the arrival of Hg in the systemic circulation is lower than expected and the contribution of Se and its absorption are high. The attempt to decrease the bioavailability of Hg has been addressed by the search for food components or food-grade microorganisms capable of decreasing the bioaccessibility of Hg after digestion or of diminishing its transport through the intestinal wall. Initial approaches have been carried out in vitro using simulated gastrointestinal digestion and cellular models of intestinal epithelium. It has been evidenced that certain types of cellulose, tannic acid, pectin and lignin are food compounds with a high binding capacity to both mercurial forms, which is maintained during gastrointestinal digestion and they are even effective in reducing the bioaccessibility of Hg from seafood products and mushrooms. These treatments do not modify the initial chemical form of Hg; however, they have the disadvantage that in some cases they reduce the bioaccessibility of essential elements. It has also been shown that digestion in the presence of lactic acid bacteria of the genus Lactobacillus and Saccharomyces cerevisiae also results in a high reduction of the bioaccessibility of Hg in aqueous solution and of Hg present in mushrooms; however, these strategies are not effective reducing the bioaccessibility of Hg present in seafood products. The analysis of the factors that could influence the inefficiency of these microorganisms in seafood products indicates that possibly the form in which Hg is released from the food matrix prevents this metal from being uptaked by bacteria and yeasts. On the other hand, it has been shown that there are dietary components, especially those with thiol groups (cysteine, GSH and homocysteine) and supplements rich in these components, as well as strains of Lactobacillus and S. cerevisiae that can reduce the transport of Hg(II) and CH3Hg through the monolayer of intestinal cells, thus affecting directly the absorption of Hg. ...El mercurio (Hg) es un metal tóxico ampliamente distribuido en el medio ambiente. La principal vía de exposición para el ser humano la constituye la dieta, donde se presenta en forma inorgánica [Hg(II)] o como metilmercurio (CH3Hg). Dentro de los alimentos que presentan elevados contenidos de este metal destacan los productos pesqueros, especialmente los grandes depredadores marinos, y las setas. La necesidad de reducir la exposición a Hg de la población, especialmente de aquellos grupos que viven en zonas contaminadas o aquellas poblaciones en las que los productos pesqueros son una base importante de sus dietas es una prioridad. Sin embargo, no es una tarea fácil evitar la contaminación del alimento o eliminar el contaminante previo a su consumo. Es por tanto necesario buscar vías alternativas para disminuir la exposición a Hg sin eliminar de la dieta alimentos con un alto valor nutritivo. Entre estas posibles vías de actuación está la de reducir selectivamente la llegada del tóxico a la circulación sanguínea tras su ingesta oral, sin comprometer la llegada de otros elementos esenciales y empleando para tal fin, compuestos cuya seguridad alimentaria esté probada. Este ha sido el objetivo principal de la presente tesis doctoral. Se ha llevado a cabo una caracterización inicial de la fracción bioaccesible de los alimentos con mayores contenidos de Hg para determinar el riesgo asociado a su ingesta. Los datos han mostrado que la cantidad de Hg que se libera durante la digestión del alimento es inferior al contenido inicial de la muestra y que ésta se ve especialmente afectada por el pH de la digestión gástrica y, en el caso de productos pesqueros, por la concentración de pepsina y lipasa pancreática. La evaluación del ratio molar selenio (Se)/Hg muestra que en las fracciones bioaccesibles hay por lo general, un exceso molar de Se, lo que según algunos estudios indica un menor riesgo asociado. Así, aunque una parte importante de estas matrices superan el límite legislado para Hg y su ingesta superaría la ingesta semanal recomendada, puede que el riesgo asociado no sea tan elevado si tal y como se observa in vitro la llegada de Hg a la circulación sistémica es menor de la esperada y el aporte de Se y su absorción son elevados. El intento de disminuir la biodisponibilidad de Hg se ha abordado mediante la búsqueda de componentes alimentarios o microrganismos de grado alimentario capaces de disminuir la bioaccesibilidad del Hg tras la digestión o de disminuir su transporte a través de la pared intestinal. Las aproximaciones iniciales se han llevado a cabo in vitro empleando una digestión gastrointestinal simulada y modelos celulares de epitelio intestinal. Se ha evidenciado que determinados tipos de celulosa, el ácido tánico, la pectina y la lignina son compuestos alimentarios con una elevada capacidad de unión a ambas formas mercuriales, la cual se mantiene durante la digestión gastrointestinal, incluso se muestran eficaces reduciendo la bioaccesibilidad de Hg desde productos pesqueros y setas. Estos tratamientos no modifican la forma química inicial del Hg, sin embargo, presentan el inconveniente de que en algunos casos reducen la bioaccesibilidad de elementos esenciales. Asimismo, se ha puesto de manifiesto que la digestión en presencia de bacterias lácticas del género Lactobacillus y de Saccharomyces cerevisiae también produce una elevada reducción de la bioaccesibilidad del Hg en disolución acuosa y del Hg presente en setas; sin embargo, estas estrategias no son efectivas reduciendo la bioaccesibilidad del Hg presente en productos pesqueros. El análisis de los posibles factores que influyen en la ineficacia de estos microrganismos en productos pesqueros indica que posiblemente la forma en que se libera el Hg de la matriz alimentaria impide que este metal pueda ser captado por bacterias y levaduras. Por otro lado, se ha puesto de manifiesto que existen componentes de la dieta,El mercuri (Hg) és un metall tòxic àmpliament distribuït en el medi ambient. La principal via d'exposició per a l'ésser humà la constitueix la dieta, on es presenta en forma inorgànica [Hg(II)] o com a metilmercuri (CH3Hg). Dins dels aliments que presenten elevats continguts d'aquest metall destaquen els productes pesquers, especialment els grans depredadors marins, i els bolets. La necessitat de reduir l'exposició a Hg de la població, especialment d'aquells grups que viuen en zones contaminades o aquelles poblacions en les quals els productes pesquers són una base important de les seves dietes és una prioritat. No obstant això, no és una tasca fàcil evitar la contaminació de l'aliment o eliminar el contaminant previ al seu consum. És per tant necessari buscar vies alternatives per disminuir l'exposició a Hg sense eliminar de la dieta aliments amb un alt valor nutritiu. Entre les possibles vies d'actuació està la de reduir selectivament l'arribada del tòxic a la circulació sanguínia després de la seua ingesta oral, sense comprometre l'arribada d'altres elements essencials i emprant per a tal fi, composts amb seguretat alimentària provada. Est ha estat l'objectiu principal de la present tesi doctoral. S'ha dut a terme una caracterització inicial de la fracció bioaccesible dels aliments amb majors continguts de Hg per determinar el risc associat a la seua ingesta. Les dades han mostrat que la quantitat de Hg que s'allibera durant la digestió de l'aliment és inferior al contingut inicial de la mostra i que aquesta es veu especialment afectada pel pH de la digestió gàstrica i, en el cas de productes pesquers, per la concentració de pepsina i lipasa pancreàtica. L'avaluació del ràtio molar seleni (Se)/Hg mostra que en les fraccions bioaccesibles hi ha en general, un excés molar de Se, la qual cosa segons alguns estudis indica un menor risc associat. Així, encara que una part important d'aquestes matrius alimentaries superen el límit legislat per Hg i la seua ingesta superaria la ingesta setmanal recomanada, pot ser que el risc associat no sigui tan elevat si tal com s'observa in vitro l'arribada de Hg a la circulació sistémica és menor de l'esperada i l'aportació de Se i la seua absorció són elevades. S'ha evidenciat que determinats tipus de cel·lulosa, l'àcid tànic, la pectina i la lignina són compostos alimentaris amb una elevada capacitat d'unió a les formes mercurials, la qual es manté durant la digestió gastrointestinal, fins i tot es mostren eficaces reduint la bioaccesibilitat de Hg des de productes pesquers i bolets. Aquests tractaments no modifiquen la forma química inicial del Hg, però presenten l'inconvenient que en alguns casos redueixen la bioaccesibilitat d'elements essencials. Així mateix s'ha posat de manifest que la digestió en presència de bacteris làctics del gènere Lactobacillus i Saccharomyces cerevisiae també produeix una elevada reducció de la bioaccesibilitat del Hg en dissolució aquosa i del Hg present en bolets; no obstant això aquestes estratègies no són efectives reduint la bioaccesibilitat del Hg present en productes pesquers. L'anàlisi dels possibles factors que influeixen en la ineficàcia d'aquests microrganismos en productes pesquers indica que possiblement la forma en que s'allibera el Hg de la matriu alimentaria impedeix que aquest metall pugui ser captat per bacteris i llevats. D'altra banda, s'ha posat de manifest que existeixen components de la dieta, principalment els que presenten grups tiol (cisteïna, GSH i homocisteïna) i suplements rics en aquests components, així com soques de Lactobacillus i S. cerevisiae que poden reduir el transport de Hg(II) i CH3Hg a través de la monocapa de cèl·lules intestinals, afectant d'aquesta forma directament l'absorció de Hg. Aquest efecte també s'observa quan s'avalua el transport del Hg present en la fracció bioaccesible de productes pesquers. L'eficàcia d'alguns compostos i microoJadán Piedra, CA. (2017). Estrategias dietéticas para disminuir la biodisponibilidad de mercurio desde alimentos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90651TESI

Polyphosphate in Lactobacillus and Its Link to Stress Tolerance and Probiotic Properties

The synthesis of the inorganic polymer polyphosphate (poly-P) in bacteria has been linked to stress survival and to the capacity of some strains to sequester heavy metals. In addition, synthesis of poly-P by certain strains of probiotic lactobacilli has been evidenced as a probiotic mechanism due to the homeostatic properties of this compound at the intestinal epithelium. We analyzed the link between poly-P synthesis, stress response, and mercury toxicity/accumulation by comparing wild-type strains of Lactobacillus and their corresponding mutants devoid of poly-P synthesis capacity (defective in the poly-P kinase, ppk, gene). Results showed that resistance to salt (NaCl) and acidic (pH 4) stresses upon ppk mutation was affected in Lactobacillus casei, while no effect was observed in two different Lactobacillus plantarum strains. Inorganic [Hg(II)] and organic (CH3Hg) mercury toxicity was generally increased upon ppk mutation, but no influence was seen on the capacity to retain both mercurial forms by the bacteria. Notwithstanding, the culture supernatants of ppk-defective L. plantarum strains possessed a diminished capacity to induce HSP27 expression, a marker for cell protection, in cultured Caco-2 cells compared to wild-type strains. In summary, our results illustrate that the role of poly-P in stress tolerance can vary between strains and they reinforce the idea of probiotic-derived poly-P as a molecule that modulates host-signaling pathways. They also question the relevance of this polymer to the capacity to retain mercury of probiotics

In vitro evaluation of dietary compounds to reduce mercury bioavailability

Mercury in foods, in inorganic form [Hg(II)] or as methylmercury (CH3Hg), can have adverse effects. Its elimination from foods is not technologically viable. To reduce human exposure, possible alternatives might be based on reducing its intestinal absorption. This study evaluates the ability of 23 dietary components to reduce the amount of mercury that is absorbed and reaches the bloodstream (bioavailability). We determined their effect on uptake of mercury in Caco-2 cells, a model of intestinal epithelium, exposed to Hg(II) and CH3Hg standards and to swordfish bioaccessible fractions. Cysteine, homocysteine, glutathione, quercetin, albumin and tannic reduce bioavailability of both mercury species. Fe(II), lipoic acid, pectin, epigallocatechin and thiamine are also effective for Hg(II). Some of these strategies also reduce Hg bioavailability in swordfish (glutathione, cysteine, homocysteine). Moreover, extracts and supplements rich in these compounds are also effective. This knowledge may help to define dietary strategies to reduce in vivo mercury bioavailability.This work was supported by the Spanish Ministry of Economy and Competitiveness (AGL2015-68920), for which the authors are deeply indebted. Carlos Jadán Piedra received a Personnel Training Grant from SENESCYT (Ecuadorian Ministry of Higher Education, Science, Technology and Innovation) to carry out this study.Peer reviewe

Influence of Physiological Gastrointestinal Parameters on the Bioaccessibility of Mercury and Selenium from Swordfish

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Agricultural and Food Chemistry, copyright © American Chemical Society after peer review and technical editing by t he publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jafc.5b05046Swordfish tend to accumulate mercury (Hg), but they are rich in selenium (Se), an element that can counteract the toxic effects of Hg. The aim of the present study was to evaluate the concentrations and bioaccessibility of Hg and Se in cooked swordfish and to identify the digestion parameters (pH, residence time, and enzyme concentrations) that may influence their bioaccessibility. The Hg concentrations ranged between 0.17 and 2.82 mg/kg wet weight (ww) and the bioaccessibility between 14 and 92%. The range for Se concentrations was narrower (0.29–1.17 mg/kg ww), with a bioaccessibility that was generally greater than that of Hg (59–103%). Most of the solubilization took place in the gastric step, where acidic pH and the increase in the pepsin concentration led to greater bioaccessibility, especially for Hg. In the intestinal stage, the most notable effect was the decrease in the bioaccessibility of Hg in the presence of bile salts.This work was supported by the Spanish Ministry of Economy and Competitiveness (AGL2012-33461)Peer reviewe

Use of Saccharomyces cerevisiae To Reduce the Bioaccessibility of Mercury from Food

Food is the main pathway of exposure to inorganic mercury [Hg(II)] and methylmercury (CH3Hg). Intestinal absorption of these mercury species is influenced by their chemical form, the luminal pH, and the composition of the diet. In this regard, strategies have been proposed for reducing mercury absorption using dietary components. This study evaluates the capacity of Saccharomyces cerevisiae to reduce the amount of mercury solubilized after gastrointestinal digestion that is available for intestinal absorption (bioaccessibility). The results show that S. cerevisiae strains reduce mercury bioaccessibility from aqueous solutions of Hg(II) (89 ± 6%) and CH3Hg (83 ± 4%), and from mushrooms (19–77%), but not from seafood. The formation of mercury–cysteine or mercury–polypeptide complexes in the bioaccessible fraction may contribute to the reduced effect of yeasts on mercury bioaccessibility from seafood. Our study indicates that budding yeasts could be useful for reducing the extent of intestinal absorption of mercury present in water and some food matrices.This work was supported by Spanish Ministry of Economy and Competitiveness Grants AGL2012-33461, AGL2015-68920, and BIO2014-56298-P, for which the authors are deeply grateful. C.J.-P. received a Personnel Training Grant from SENESCYT (Ecuadorian Ministry of Higher Education, Science, Technology and Innovation) to perform this study.Peer reviewe

Characterization of the binding capacity of mercurial species in Lactobacillus strains

BACKGROUND: Metal sequestration by bacteria has been proposed as a strategy to counteract metal contamination in foodstuffs. Lactobacilli can interact with metals, although studies with important foodborne metals such as inorganic [Hg(II)] or organic (CH3Hg) mercury are lacking. Lactobacilli were evaluated for their potential to bind these contaminants and the nature of the interaction was assessed by the use of metal competitors, chemical and enzymatical treatments, and mutants affected in the cell wall structure. RESULTS: Lactobacillus strains efficiently bound Hg(II) and CH3Hg. Mercury binding by Lactobacillus casei BL23 was independent of cell viability. In BL23, both forms of mercury were cell wall bound. Their interaction was not inhibited by cations and it was resistant to chelating agents and protein digestion. Lactobacillus casei mutants affected in genes involved in the modulation of the negative charge of the cell wall anionic polymer lipoteichoic acid showed increased mercury biosorption. In these mutants, mercury toxicity was enhanced compared to wild-type bacteria. These data suggest that lipoteichoic acid itself or the physicochemical characteristics that it confers to the cell wall play a major role in mercury complexation. CONCLUSION: This is the first example of the biosorption of Hg(II) and CH3Hg in lactobacilli and it represents a first step towards their possible use as agents for diminishing mercury bioaccessibility from food at the gastrointestinal tract. © 2017 Society of Chemical IndustryThis work was supported by the Spanish Ministry of Economy and Competitiveness under grants AGL2012-33461, AGL2013-40657-R and AGL2015-68920-R. Carlos Jadán-Piedra received a Personnel Training Grant from SENESCYT (Ecuadorian Ministry of Higher Education, Science, Technology and Innovation).Peer reviewe

The use of lactic acid bacteria to reduce mercury bioaccessibility

Mercury in food is present in either inorganic [Hg(II)] or methylmercury (CH3Hg) form. Intestinal absorption of mercury is influenced by interactions with other food components. The use of dietary components to reduce mercury bioavailability has been previously proposed. The aim of this work is to explore the use of lactic acid bacteria to reduce the amount of mercury solubilized after gastrointestinal digestion and available for absorption (bioaccessibility). Ten strains were tested by addition to aqueous solutions containing Hg(II) or CH3Hg, or to food samples, and submission of the mixtures to gastrointestinal digestion. All of the strains assayed reduce the soluble fraction from standards of mercury species under gastrointestinal digestion conditions (72–98%). However their effectiveness is lower in food, and reductions in bioaccessibility are only observed with mushrooms (⩽68%). It is hypothesized that bioaccessible mercury in seafood forms part of complexes that do not interact with lactic acid bacteria.his work was supported by the Spanish Ministry of Economy and Competitiveness (AGL2012-33461; AGL2013-40657; AGL2015-68920), for which the authors are deeply indebted. Carlos Jadán Piedra received a Personnel Training Grant from SENESCYT (Ecuadorian Ministry of Higher Education, Science, Technology and Innovation) to carry out this study.Peer reviewe

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

Use of lactic acid bacteria and yeasts to reduce exposure to chemical food contaminants and toxicity

Chemical contaminants that are present in food pose a health problem and their levels are controlled by national and international food safety organizations. Despite increasing regulation, foods that exceed legal limits reach the market. In Europe, the number of notifications of chemical contamination due to pesticide residues, mycotoxins and metals is particularly high. Moreover, in many parts of the world, drinking water contains high levels of chemical contaminants owing to geogenic or anthropogenic causes. Elimination of chemical contaminants from water and especially from food is quite complex. Drastic treatments are usually required, which can modify the food matrix or involve changes in the forms of cultivation and production of the food products. These modifications often make these treatments unfeasible. In recent years, efforts have been made to develop strategies based on the use of components of natural origin to reduce the quantity of contaminants in foods and drinking water, and to reduce the quantity that reaches the bloodstream after ingestion, and thus, their toxicity. This review provides a summary of the existing literature on strategies based on the use of lactic acid bacteria or yeasts belonging to the genus Saccharomyces that are employed in food industry or for dietary purposes.This work was supported by the Spanish Ministry of Economy and Competitiveness (AGL2015-68920), for which the authors are deeply indebted. Gabriela de Matuoka e Chiocchetti received a fellowship from the Brazilian Government (CAPES-proceso BEX1086/14-6) and Carlos Jadán-Piedra received a Personnel Training Grant from SENESCYT (Ecuadorian Ministry of Higher Education, Science, Technology and Innovation).Peer reviewe