Ruminal disappearance of PAHs in contaminated grass using the nylon bag technique

Airborne polycyclic aromatic hydrocarbons (PAHs) are deposited on agricultural grasses. In turn, PAHs enter the food chain through animals eating grasses. However, the risk of food contamination, e.g. of milk, is unknown because mechanisms ruling the fate of PAHs during digestion by cows are not understood, especially in the rumen. Here, we studied the disappearance rate of phenanthrene, pyrene and benzo[a]pyrene, n-alkanes, and dry matter from contaminated grass samples in the rumen, the first compartment of the ruminant digestive tract. Three cows fitted with a rumen cannula were used for this study and the grass samples were incubated in sacco for 1, 3, 6, 12, 24 and 48 h. The results show that the disappearance rate of PAHs was fast and higher than that of n-alkanes. On average, 83% of PAHs disappeared after 1 h of incubation. Phenanthrene showed a disappearance rate higher than 90%. The findings suggest a fast desorption of PAHs from the surface of the grass leaves. The digestive hydrolysis of the grass is not required to release PAHs, contrary to other fractions. As a consequence, the bioavailability of PAHs is not limited by the grass

Deposition of platinum group elements and polycyclic aromatic hydrocarbons on ryegrass exposed to vehicular traffic

Along highways, platinum group elements (PGE: Pt, Pd and Rh) and polycyclic aromatic hydrocarbons (PAHs) produced by the vehicle traffic can be deposited on grass and soil, leading to a risk of contamination through the food chain via farm animals. We studied the deposition of platinum group elements and polycyclic aromatic hydrocarbons on ryegrass pots exposed along a highway with 65 000 vehicles per day for 90 days in summer and autumn. After this exposure period, the ryegrass pots were transferred to a remote area for 5 weeks. The Pt, Pd and Rh concentrations were determined in ryegrass samples using inductively coupled plasma mass spectrometry (ICP-MS) and PAHs were quantified by high-pressure liquid chromatography (HPLC). Our results show that Pd and Rh concentrations increased with time of exposure. Pd concentrations ranged from 1.5 to 6.8 ng/g dry weight (d.w.), Rh from 1.5 to 3 ng/g d.w. and Pt from 0.3 to 1.4 ng/g d.w. The total PAH concentrations varied from 6 to 175 ng/g d.w. PGE and PAH deposition on ryegrass near the highway occurred mainly for the first weeks of exposure. During the 5 weeks following the exposure, the levels and profiles of PAHs and PGE (except Rh) in highway grasses transferred to a remote area did not significantly decrease, suggesting a potential risk of contamination for dairy ruminants

Efficiency assessment of soil amendment with biochars and activated carbons to limit CLD transfer to animal using in vitro and in vivo assays

International audienceChlordecone (Kepone) (CLD) is a highly persistent pesticide formerly used in French West Indies. Nowadays high levels of this pesticide are still found in soils which represent a subsequent source of contamination for outdoor-reared animals. In that context, sequestering matrices as activated carbons (ACs) or biochars are believed to efficiently decrease CLD transfer to animals. The present study intends to test using 2 distinct in vitro tests prior an in vivo assay the respective efficiency of several biochars and ACs to limit CLD transfer to animals. The Te-PBET and the ISO/DIS 16 751 availability part A protocols were used. In each test amended soils were prepared from a control one (SS) by adding 2% (mass basis) of one of the ACs or biochar. A selection of interesting matrices was realized prior the in vivo part of the protocol. For this final step piglets were exposed by alimentary route to contaminated soils. Only treatment groups exposed through amended soil with ACs presented significant decreases CLD availability, bioaccessibility (< 8%). Similar results were found using both in vitro assays. At last, concentrations of CLD in piglets liver and adipose tissue were found significantly lower after exposition to an AC amended soil (p< 0.001). This decrease was particularly high for a coconut shell activated carbon where relative bioavailability was found lower than 3% for both tissues. Finally, a positive correlation was found between environmental availability, bioaccessibility tests and in vivo results. This study leads to conclude that (i) AC introduced in CLD contaminated soil should strongly reduce CLD availability; bioaccessibility and bioavailability (ii) Tested biochars showed no reduction of transfert (iii) availability and bioaccessibility tests could be useful screening tests in order to select the appropriate biochar or AC

Adhesion Properties of Probiotic <i>Lactobacillus</i> Strains Isolated from Tunisian Sheep and Goat Milk

International audienceFour hundred strains isolated from Tunisian sheep and goat raw milks were initially screened for their ability to survive the GastroIntestinal Tract (GIT). Forty-three among the four hundred bacteria were resistant to pepsin, pH 2, pancreatin and bile salts at 0.3%, even after 5 hours of incubation. Identification using 16S rRNA gene sequencing was established and we obtained as a species Lactobacillus plantarum (29 isolates from sheep milk and 11 from goat milk) and Lactobacillus pentosus (2 isolates from sheep milk and 1 from goat milk). We showed the ability for auto-aggregation and/or hydrophobicity properties. Finally, both M63 and C78 strains showed an important level of adhesion to three intestinal epithelial cells Caco-2 TC7, HT29-MTX, and HT29-CL.16E. Taken together, these properties allow the lactobacilli strains to be considered promising beneficial strains for developing functional foods for consumers

Surface proteins involved in the adhesion of Streptococcus salivarius to human intestinal epithelial cells

International audienceThe adhesion properties of 14 Streptococcus salivarius strains to mucus (HT29-MTX) and non-mucus secreting (Caco-2/TC7) human intestinal epithelial cells were investigated. Ability to adhere to these two eukaryotic cell lines greatly differs between strains. The presence of mucus played a major factor in adhesion, likely due to high adhesiveness to mucins present in the native human mucus layer covering the whole cell surface. Only one S. salivarius strain (F6-1), isolated from the feces of a healthy baby, was found to strongly adhere to HT-29 MTX cells at a level comparable to that of Lactobacillus rhamnosus GG, a probiotic strain considered to be highly adherent. By sequencing the genome of F6-1, we were able to identify 36 genes encoding putative surface proteins. Deletion mutants were constructed for six of them and their adhesion abilities on HT-29 MTX cells were checked. Our study confirmed that four of these genes encode adhesins involved in the adhesion of S. salivarius to host cells. Such adhesins were also identified in other S. salivarius strains

La méthanisation thermophile permet de dégrader la chlordécone

International audienceLa présence avérée de la chlordécone (CLD) dans la biomasse végétale et dans les déjections des animaux pose un problème supplémentaire dans la gestion de la pollution. Il faut en effet veiller à ne pas déplacer ces matrices contaminées sur des zones non polluées tout en les valorisant. Dans cet objectif, nous avons étudié une synergie potentielle entre la valorisation énergétique de ces biomasses, avec retour au sol de la matière organique, et la dégradation de la CLD.Les études de dégradation de la CLD ont montré que la transformation biotique de la CLD est possible et se traduit par la production de plusieurs familles de produits de transformation (PTs). Ces études mettent en évidence l'importance des conditions particulières suivantes : conditions réductrices, absence d'oxygène, ainsi que présence de micro-organismes capables de dégrader la CLD, notamment ceux produisant des corrinoïdes1 et/ou le coenzyme F430 . Ces observations nous ont amenés à supposer que le procédé de méthanisation, qui nécessite principalement un potentiel redox inférieur ou égal à -300 mV , l'absence d'oxygène et la présence de consortia de microorganismes pourrait se révéler une stratégie efficace pour dégrader la CLD et traiter les déchets organiques contaminés

Neurotrophic Effect of Fish-Lecithin Based Nanoliposomes on Cortical Neurons

International audienceLipids play multiple roles in preserving neuronal function and synaptic plasticity, and polyunsaturated fatty acids (PUFAs) have been of particular interest in optimizing synaptic membrane organization and function. We developed a green-based methodology to prepare nanoliposomes (NL) from lecithin that was extracted from fish head by-products. These NL range between 100-120 nm in diameter, with an n-3/n-6 fatty acid ratio of 8.88. The high content of n-3 PUFA (46.3% of total fatty acid content) and docosahexanoic acid (26%) in these NL represented a means for enrichment of neuronal membranes that are potentially beneficial for neuronal growth and synaptogenesis. To test this, the primary cultures of rat embryo cortical neurons were incubated with NL on day 3 post-culture for 24 h, followed by immunoblots or immunofluorescence to evaluate the NL effects on synaptogenesis, axonal growth, and dendrite formation. The results revealed that NL-treated cells displayed a level of neurite outgrowth and arborization on day 4 that was similar to those of untreated cells on day 5 and 6, suggesting accelerated synapse formation and neuronal development in the presence of NL. We propose that fish-derived NL, by virtue of their n-3 PUFA profile and neurotrophic effects, represent a new innovative bioactive vector for developing preventive or curative treatments for neurodegenerative diseases

Streptococcus macedonicus strains isolated from traditional fermented milks: resistance to gastrointestinal environment and adhesion ability

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Adhesive interactions between milk fat globule membrane and Lactobacillus rhamnosus GG inhibit bacterial attachment to Caco-2 TC7 intestinal cell

International audienceMilk is the most popular matrix for the delivery of lactic acid bacteria, but little is known about how milk impacts bacterial functionality. Here, the adhesion mechanisms of Lactobacillus rhamnosus GG (LGG) surface mutants to a milk component, the milk fat globule membrane (MFGM), were compared using atomic force microscopy (AFM). AFM results revealed the key adhesive role of the LGG SpaCBA pilus in relation to MFGM. A LGG mutant without exopolysaccharides but with highly exposed pili improved the number of adhesive events between LGG and MFGM compared to LGG wild type (WT). In contrast, the number of adhesive events decreased significantly for a LGG mutant without SpaCBA pili. Moreover, the presence of MFGM in the dairy matrix was found to decrease significantly the bacterial attachment ability to Caco-2 TC7 cells. This work thus demonstrated a possible competition between LGG adhesion to MFGM and to epithelial intestinal cells. This competition could negatively impact the adhesion capacity of LGG to intestinal cells in vivo, but requires further substantiation

La méthanisation thermophile permet de dégrader la chlordécone

International audienceLa présence avérée de la chlordécone (CLD) dans la biomasse végétale et dans les déjections des animaux pose un problème supplémentaire dans la gestion de la pollution. Il faut en effet veiller à ne pas déplacer ces matrices contaminées sur des zones non polluées tout en les valorisant. Dans cet objectif, nous avons étudié une synergie potentielle entre la valorisation énergétique de ces biomasses, avec retour au sol de la matière organique, et la dégradation de la CLD.Les études de dégradation de la CLD ont montré que la transformation biotique de la CLD est possible et se traduit par la production de plusieurs familles de produits de transformation (PTs). Ces études mettent en évidence l'importance des conditions particulières suivantes : conditions réductrices, absence d'oxygène, ainsi que présence de micro-organismes capables de dégrader la CLD, notamment ceux produisant des corrinoïdes1 et/ou le coenzyme F430 . Ces observations nous ont amenés à supposer que le procédé de méthanisation, qui nécessite principalement un potentiel redox inférieur ou égal à -300 mV , l'absence d'oxygène et la présence de consortia de microorganismes pourrait se révéler une stratégie efficace pour dégrader la CLD et traiter les déchets organiques contaminés