Campylobacter contamination of broiler caeca and carcasses at the slaughterhouse and correlation with Salmonella contamination

In order to estimate the prevalence of Campylobacter spp. and Salmonella spp. on broiler chicken carcasses and the prevalence of Campylobacter spp. in caeca, 58 French slaughterhouses were investigated in 2008. Enumeration of Campylobacter spp. was also performed in order to study the relation between caeca and carcass contamination. A pool of 10 caeca and one carcass were collected from 425 different batches over a 12-month period in 2008. Salmonella was isolated on 32 carcasses leading to a prevalence of 7.5% ([5.0-10.0]_95%CI). The prevalence of Campylobacter was 77.2% ([73.2-81.2]_95%CI) in caeca and 87.5% ([84.4-90.7]_95%CI) on carcasses. No significant correlation was found between Campylobacter and Salmonella. Positive values of Campylobacter were normally distributed and the average level was 8.05 log₁₀ cfu/g ([7.94-8.16]_95%CI) in caeca and 2.39 cfu/g ([2.30-2.48]_95%CI) on carcasses. A positive correlation (r = 0.59) was found between the mean of Campylobacter in caeca and on carcasses (p < 0.001). Thus, carcasses from batches with Campylobacter-positive caeca had significantly (p < 0.001) higher numbers of Campylobacter per gram than batches with negative caeca. These results show that Campylobacter can be present in both matrices and reduction in caeca could be a possible way to reduce the amount of bacteria on carcasses. Of the 2504 identifications performed, 3 species of Campylobacter (Campylobacter jejuni, Campylobacter coli and Campylobacter lari) were identified. The main species recovered were C. jejuni and C. coli, which were isolated in 55.3% and 44.5% of positive samples, respectively. These two species were equally represented in caeca but C. jejuni was the most frequently isolated on carcasses with 57.1% and 42.5% of positive carcasses for C. jejuni and C. coli, respectively. This study underlines that target a reduction of Campylobacter on final products requires a decrease of contamination in caeca.     

Effect of biochar in enhancing hydrogen production by mesophilic anaerobic digestion of food wastes: The role of minerals

The role of minerals in biochar in promoting hydrogen (H₂) production by anaerobic digestion of food waste was investigated. The cultures with the addition of biochar, leached biochar, metal sulphate solution and leached biochar combined with metal sulphate solution, respectively, were placed in bench-scale reactors and incubated at incubator at 32 °C. Daily H₂ production and volatile fatty acids (VFAs) were measured and the cumulative H₂ yield (Y_H) and maximum H₂ production rate (R_H) were calculated. The microbial analysis was performed using Illumina MiSeq sequencing. Biochar addition significantly increased the maximum Y_H by 107% and R_H by 54%. However, the addition of leached biochar only increased the maximum Y_H by 39% and R_H by 45% than control. The primary elements in biochars that contribute to H₂ production (Fe, K and Ca) were shown to increase the acetic acid, butyric acid and prevalence of the H₂ producing bacteria Clostridium butyricum.     

Effect of humic substance photoalteration on lead bioavailability to freshwater microalgae

The present study provides results on the influence of humic substance (HS) photoalteration on lead availability to the freshwater microalga Chlorella kesslerii . The evolution of the free lead-ion concentrations measured by the ion exchange technique [Pb](IET) and intracellular lead contents was explored in the presence of Suwannee River humic (SRHA) and fulvic (SRFA) acids, as well as Aldrich humic acid (AHA) exposed at increasing radiance doses under a solar simulator. Modifications of HS characteristics highly relevant to Pb complexation and accumulation of HS to algal surfaces, including Fourier transform infrared spectroscopy, were followed. It was demonstrated that simulated sunlight exposure of HS increased [Pb](IET) in the medium for SRFA and SRHA, but had no effect for AHA. No clear relationship was observed between the changes in free lead-ion concentrations and intracellular content in alga for all studied HS, suggesting that HS photodegradation products also exhibit Pb complexation properties, and that direct interactions between HS and alga are affected. Indeed, photoalteration of humic substances reduced the adsorption of HS to the algal surface; the effect was more pronounced for SRFA and AHA and less significant for SRHA. The bioavailability results were consistent with the characterization of the phototransformation of humic substances: Pb speciation changes followed the modification of the relative abundance of the carboxylic groups and their molecular environment, while the reduced HS adsorption to the alga correlated with losses of the double bond abundance and aromaticity.     

Biological activities of flavonoids from Nitraria retusa (Forssk.) Asch. and their acylated derivatives

The antioxidant activity and antiproliferative property towards Caco2 cells of water and methanol extracts/fractions of Nitraria retusa were investigated. The total phenolic and flavonoid contents of the extracts/fractions were determined, and the four major flavonoids were identified as isorhamnetin, isorhamnetin-3-O-glucoside, isorhamnetin-3-O-rutinoside and isorhamnetin-3-O-robinobioside. The results showed a relationship between the extracts/fractions activities and their flavonoid contents. Moreover, the chloroform extract which was enriched with the aglycone flavonoid isorhamnetin exhibited the highest activities. The activities of N. retusa flavonoids were compared to those of model flavonoids, quercetin, isoquercitrin and rutin. In all cases, the aglycone compounds were more active than their glycosylated derivatives. Isorhamnetin-based flavonoids presented higher antiproliferative activities than quercetin-based ones, while similar antioxidant properties were observed. The enzymatic acylation of isorhamnetin-3-O-glucoside with ethyl laurate and ethyl butyrate enhanced its capacity to inhibit xanthine oxidase and its antiproliferative activity but decreased its radical scavenging activity.     

X-ray absorption fine structure evidence for amorphous zinc sulfide as a major zinc species in suspended matter from the Seine River downstream of Paris, Ile-de-France, France

Zinc is one of the most widespread trace metals (TMs) in Earth surface environments and is the most concentrated TM in the downstream section of the Seine River (France) due to significant anthropogenic input from the Paris conurbation. In order to better identify the sources and cycling processes of Zn in this River basin, we investigated seasonal and spatial variations of Zn speciation in suspended particulate matter (SPM) in the oxic water column of the Seine River from upstream to downstream of Paris using synchrotron-based extend X-ray absorption fine structure (EXAFS) spectroscopy at the Zn K-edge. First-neighbor contributions to the EXAFS were analyzed in SPM samples, dried and stored under a dry nitrogen atmosphere or under an ambient oxygenated atmosphere. We found a sulfur first coordination environment around Zn (in the form of amorphous zinc sulfide) in the raw SPM samples stored under dry nitrogen vs an oxygen first coordination environment around Zn in the samples stored in an oxygenated atmosphere. These findings are supported by scanning electron microscopy and energy dispersive X-ray spectrometry observations. Linear combination fitting of the EXAFS data for SPM samples, using a large set of EXAFS spectra of Zn model compounds, indicates dramatic changes in the Zn speciation from upstream to downstream of Paris, with amorphous ZnS particles becoming dominant dowstream. In contrast, Zn species associated with calcite (either adsorbed or incorporated in the structure) are dominant upstream. Other Zn species representing about half of the Zn pool in the SPM consist of Zn-sorbed on iron oxyhydroxides (ferrihydrite and goethite) and, to a lesser extent, Zn-Al layered double hydroxides, Zn incorporated in dioctahedral layers of clay minerals and Zn sorbed to amorphous silica. Our results highlight the importance of preserving the oxidation state in TM speciation studies when sampling suspended matter, even in an oxic water column.     

Modifications of bull spermatozoa induced by three extenders: Biociphos, low density lipoprotein and Triladyl, before, during and after freezing and thawing

The success of artificial insemination with frozen semen implies the reduction of the deleterious effects on the cells induced by this technique. These effects can occur as early as during the first dilution in an extender, as well as at any step, during or after the freezing process.In this work, we have compared the modifications induced by Triladyl, low density lipoproteins (LDL) and Biociphos extenders, after dilution and cooling to 4 degrees C for 1, 4 and 24 h. Alterations in the cell structures were visualized by electron microscopy (EM). More than 80% of spermatozoa were injured after incubation for 4 h in Triladyl, while 3% and 47% were counted in LDL and Biociphos respectively. This latter extender was deleterious to cell membrane integrity after incubation for 4 h or longer.The ultrastructure of frozen spermatozoa was studied by EM of cryofixed-cryosubstituted samples obtained from regular 0.5 ml French straws frozen using our usual protocol. The main differences between samples concerned the size and appearance of the frozen extender veins, while very few cell defects were found to be added by the freezing process at any depth in the straws.After thawing, semen motility was twofold higher (P < 0.05) in Biociphos (64%) and LDL (61%) than in Triladyl (32%) and the cells were less altered in LDL. We concluded that the LDL extender offers a better protection for storage of frozen spermatozoa, and can probably also be used for the preservation of fresh semen for short periods.     

Petit suisse manufactured with cheese whey retentate and application of betalains and anthocyanins

Petit suisse cheese was elaborated with substitution of 30% milk volume for cheese whey retentate (volumetric reduction ratio=5.0) obtained by ultrafiltration (cheese 1) and 100% milk (cheese 2). These were evaluated regarding physicochemical composition: moisture, ash, total solids, lipids, total proteins, acidity in lactic acid and pH. Natural pigments were added to the cheeses: Cabernet Sauvignon (Vitis vinifera L.) grape anthocyanins or (Beta vulgaris L.) beetroot betalains. The cheese samples were maintained at 6±1 °C for 40 days in light-impermeable packaging and evaluated regarding pigment stability by determining half-life time and percentage color retention. The results of the physicochemical analyses demonstrated that significant differences occurred between cheeses 1 and 2 regarding total solid content, moisture, protein, lipids and carbohydrates. The half-life time and percentage color retention values obtained for the anthocyanin and betalain extracts added to the cheeses were adequate for the shelf life of this product.     

Contribution to the modelling of interfaces in masonry construction

The aim of this study was to model the mechanical behavior of interfaces in masonry structures. In the first part, the characteristics of the materials and interfaces involved are determined experimentally. In the second part, a model based on the adhesion intensity is developed. This model can be used to describe the interfaces between mortar and full or hollow bricks and to describe the damage occuring in the mortar. The mechanical behavior predicted by this model is compared with previously obtained experimental data. The model is then tested in the case of some classical masonry structures (small walls, diagonal compression tests).