Roua Rejeb

Bio: Roua Rejeb is an academic researcher from Institut Supérieur Agronomique de Chott-Mariem. The author has contributed to research in topics: Adsorption & Point of zero charge. The author has an hindex of 1, co-authored 2 publications receiving 8 citations. Previous affiliations of Roua Rejeb include Ghent University.

Calcination Enhances the Aflatoxin and Zearalenone Binding Efficiency of a Tunisian Clay.

Abstract: Clays are known to have promising adsorbing characteristics, and are used as feed additives to overcome the negative effects of mycotoxicosis in livestock farming. Modification of clay minerals by heat treatment, also called calcination, can alter their adsorption characteristics. Little information, however, is available on the effect of calcination with respect to mycotoxin binding. The purpose of this study was to characterize a Tunisian clay before and after calcination (at 550 °C), and to investigate the effectiveness of the thermal treatment of this clay on its aflatoxin B1 (AFB1), G1 (AFG1), B2 (AFB2), G2 (AFG2), and zearalenone (ZEN) adsorption capacity. Firstly, the purified clay (CP) and calcined clay (CC) were characterized with X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR-IR), cation exchange capacity (CEC), specific surface area (SBET), and point of zero charge (pHPZC) measurements. Secondly, an in vitro model that simulated the pH conditions of the monogastric gastrointestinal tract was used to evaluate the binding efficiency of the tested clays when artificially mixed with aflatoxins and zearalenone. The tested clay consisted mainly of smectite and illite. Purified and calcined clay had similar chemical compositions. After heat treatment, however, some changes in the mineralogical and textural properties were observed. The calcination decreased the cation exchange capacity and the specific surface, whereas the pore size was increased. Both purified and calcined clay had a binding efficacy of over 90% for AFB1 under simulated poultry GI tract conditions. Heat treatment of the clay increased the adsorption of AFB2, AFG1, and AFG2 related to the increase in pore size of the clay by the calcination process. ZEN adsorption also increased by calcination, albeit to a more stable level at pH 3 rather than at pH 7. In conclusion, calcination of clay minerals enhanced the adsorption of aflatoxins and mostly of AFG1 and AFG2 at neutral pH of the gastrointestinal tract, and thus are associated with protection against the toxic effects of aflatoxins.

Calcination Improves the In Vivo Efficacy of a Montmorillonite Clay to Bind Aflatoxin G1 in Broiler Chickens: A Toxicokinetic Approach.

Abstract: The goal of this study was to investigate the toxicokinetic characteristics of aflatoxin G1 (AFG1) in broiler chickens and the effect of calcination of a Tunisian montmorillonite clay on the in vivo absorption of AFG1. In this study, broiler chickens were randomly distributed into four groups of 10 animals. Group 1 was administered AFG1 (2 mg/kg body weight (BW)) by single intravenous injection (IV), group 2 received an intra-crop bolus (PO) of AFG1 without any clay, group 3 was dosed AFG1 PO together with an oral bolus of purified clay (CP), and group 4 received AFG1 PO with an oral bolus of calcined clay. A significant difference in the area under the curve (AUC0-t) was observed for group 4 (6.78 ± 4.24 h*ng/mL) in comparison with group 2 (12.83 ± 4.19 h*ng/mL). A significant reduction of the oral bioavailability of AFG1 was observed for group 4 (7.61 ± 4.76%) compared with group 2 (14.40 ± 4.70%), while no significant effect was observed of CP. In this experiment, no phase I nor phase II metabolites of AFG1 were observed. These findings confirm that calcination of the purified montmorillonite clay enhances the adsorption of AFG1 in the gastrointestinal tract after oral administration, thereby reducing its bioavailability, thus reducing its toxic effects.

Assessing the Aflatoxins Mitigation Efficacy of Blueberry Pomace Biosorbent in Buffer, Gastrointestinal Fluids and Model Wine.

Abstract: Blueberry (BB) and cherry pomace were investigated as new biosorbents for aflatoxins (AFs) sequestration from buffered solutions, gastrointestinal fluids and model wine. Among the tested biosorbents, BB exhibited the maximum adsorption performance for AFs and hence was further selected for the optimization of experimental parameters like pH, dosage, time and initial concentration of AFs. Material characterizations via scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, N2 adsorption-desorption isothermal studies, thermogravimetric analysis (TGA) and X-ray photon spectroscopy (XPS) techniques revealed useful information about the texture and chemical composition of the biosorbents. The fitting of isothermal data with different models showed the model suitability trend as: Sips model > Langmuir model > Freundlich model, where the theoretical maximum adsorption capacity calculated from the Sips model was 4.6, 2.9, 2.7 and 2.4 mg/g for AFB1, AFB2, AFG1 and AFG2, respectively. Kinetics study revealed the fast AFs uptake by BB (50–90 min) while thermodynamics studies suggested the exothermic nature of the AFs adsorption from both, single as well as multi-toxin buffer systems, gastrointestinal fluids and model wine. Accrediting to the fast and efficient adsorption performance, green and facile fabrication approach and cost-effectiveness, the newly designed BB pomace can be counted as a promising contender for the sequestration of AFs and other organic pollutants.

Mycotoxin Contamination Management Tools and Efficient Strategies in Feed Industry.

Abstract: Mycotoxins represent a risk to the feed supply chain with an impact on animal health, feed industry, economy, and international trade. A high percentage of feed samples have been reported to be contaminated with more than one mycotoxin. Multi-mycotoxin contamination is a topic of great concern, as co-contaminated samples might still exert adverse effects on animals due to additive/synergistic interactions of the mycotoxins. Since mycotoxin contamination cannot be completely prevented preor post-harvest, precise knowledge of mycotoxin occurrence, repartitioning during technological processes and decontamination strategies are critical and may provide a sound technical basis for feed managers to conform to legislation requirements and reduce the risk of severe adverse health, market and trade repercussions. Castaldo et al. [1] developed and validated a quantitative method, using an acetonitrile-based extraction and an ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS), for a multi-mycotoxin screening of 28 mycotoxins and identification of other 45 fungal and bacterial metabolites in dry pet food samples. Results showed mycotoxin contamination in 99% of pet food samples and all positive samples showed co-occurrence of mycotoxins with the simultaneous presence of up to 16 analytes per sample. Strategies must be developed for mycotoxin reduction in feedstuffs. Čolović et al. [2] reviewed the most recent findings on different processes and strategies for the reduction of toxicity of mycotoxins in animals giving detailed information about the decontamination approaches to mitigate mycotoxin contamination of feedstuffs and compound feed, which could be implemented in practice. Authors conclude that there is increasing business interest in the use of feed additives to avoid mycotoxin absorption and the toxic impacts on farm animals. The efficacy of the additives for the distinct mycotoxins and livestock is a critical point and must be proved. It is recommended that cell lines or in vitro models be used in the simulation instead of living experimental animals. In this scenario, a group of papers deals with in vitro models for assessing mycotoxin toxicity and risk mitigation strategies. Xu et al. [3] reviewed different in vitro intestinal epithelial cells (IECs) or co-culture models that can be used for assessing mycotoxin exposure, toxicity, and risk mitigation. Since ingestion is the most common route of mycotoxin exposure, the intestinal epithelial barrier, comprised of IECs and immune cells such as macrophages, represents ground zero where mycotoxins are absorbed, biotransformed, and elicit toxicity. Several articles investigated the efficacy of feed additives as multi-mycotoxin adsorbent by using in vitro gastro-intestinal models. Adunphatcharaphon et al. [4] characterised and analysed acid-treated durian peel (ATDP), an agricultural waste, for simultaneous adsorption of mycotoxins. Results indicated the potential of ATDP as a multi-mycotoxin biosorbent for aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEN), and fumonisin B1 (FB1), but negligible towards deoxynivalenol (DON). Kolawole et al. [5] carried out a study to assess the efficacy of commercially available feed additives with multi-mycotoxin-binding claims. Their capacity to simultaneously adsorb

Enhanced Malachite Green uptake using chemically-modified reed-based powder: equilibrium, kinetics, mechanism, and reusability

Abstract: Novel bio-adsorbents based on abundant and invasive plants such as reeds represent an original and ecological route for the development of innovative biomaterials. Sustainable, eco-efficient, and f...