White-Rot Fungi and their Enzymes as a Biotechnological Tool for Xenobiotic Bioremediation

A huge amount of hazardous organopollutants, often persistent and toxic, is produced annually over the world and may contaminate soil, water, ground water, and air. Being from various sources such as wastewater, landfill leachates, and solid residues, xenobiotics include phenols, plastics, hydrocarbons, paints, dyes, pesticides and insecticides, paper and pulp mills, and pharmaceuticals. Among biological processes for degradation of xenobiotics, fungal ones, being eco-friendly and cost cheap, have been investigated extensively because most of basidiomycetes are more tolerant to high concentrations of pollutants. Fungal bioremediation is a promising technology using their metabolic potential to remove or reduce xenobiotics. Basidiomycetes are the unique microorganisms that show high capacities of degrading a wide range of toxic xenobiotics. They act via the extracellular ligninolytic enzymes, including laccase, manganese peroxidase, and lignin peroxidase. Their capacities to remove xenobiotic substances and produce polymeric products make them a useful tool for bioremediation purposes. During fungal remediation, they utilize hazardous compounds, even the insoluble ones, as the nutrient source and convert them to simple fragmented forms. The aim of this chapter is to elucidate the ability of basidiomycetes to degrade xenobiotics. This is an overview to present the importance of extracellular enzymes for efficient bioremediation of a large variety of xenobiotics

Critical Behavior of La0.8Ca0.2Mn1−xCoxO3 Perovskite (0.1 ≤ x ≤ 0.3)

The critical properties of La0.8Ca0.2Mn1−xCoxO3 (x = 0, 0.1, 0.2 and 0.3) compounds were investigated by analysis of the magnetic measurements in the vicinity of their critical temperature. Arrott plots revealed that the paramagnetic PM-ferromagnetic (FM) phase transition for the sample with x = 0 is a first order transition, while it is a second order transition for all doped compounds. The critical exponents β, γ and δ were evaluated using modified Arrott plots (MAP) and the Kouvel-Fisher method (KF). The reliability of the evaluated critical exponents was confirmed by the Widom scaling relation and the universal scaling hypothesis. The values of the critical exponents for the doped compounds were consistent with the 3D-Heisenberg model for magnetic interactions. For x = 0.1, the estimated critical components are found inconsistent with any known universality class. In addition, the local exponent n was determined from the magnetic entropy change and found to be sensitive to the magnetic field in the entire studied temperature range.This work has been supported by the Tunisian Ministry of Scientific Research and Technology and Institute Neel at Grenobl

Detoxification assays of tunisian tannery wastewater under nonsterile conditions using the filamentous fungus aspergillus Niger

The ability of Aspergillus Niger strain to reduce organic and mineral pollution as well as the toxicity of two tannery wastewaters, the unhairing effluent (UE) and the final effluent (FE), taken from a local Tunisian tannery and under nonsterile conditions, was studied. Raw effluents show alkaline pH ?11; thus experiments were carried out at initial pH values and at pH adjusted to 6. Characterization of effluents also revealed high salt levels (EC > 17 mS/cm) and high organic matter content (25 g/L for the UE and 7.2 g/L for the FE) but a low biodegradability since BOD5 did not exceed 2.5 and 1.25 g/L for the UE and the FE, respectively. The results of the biological treatment showed that A. Niger was able not only to grow at high pH and salinity values, but also to reduce organic and mineral pollutant load. After treatment, the COD reduction for the UE reached 90% and 70% at pH=6 and at initial pH (12.13), respectively. For the FE, the decrease of COD values reached 75% at pH=6 and 64% at initial pH (11.64). Monitoring of mineral pollution levels showed a reduction in chromium (Cr) concentrations reaching 70% for the FE. This was reflected by an increase of the biomass of A. Niger from 9.25 g/L (control) to 9.84 g/L for the FE. To confirm the efficiency of the biological treatment using A. Niger, phytotoxicity (tomato seeds) and microtoxicity (Escherichia coli and Bacillus subtilis) tests were carried out. Results of this monitoring showed an important decrease in the toxicity levels for both effluents. - 2019 Raouia Boujelben et al.The present research study was supported by the Ministry of Higher Education and Scientific Research-Tunisia under Research Contract Program of the Environmental Bioprocesses Laboratory. The authors thank Mr. Slim LOUKIL and Mr. Nidhal BACCAR for their technical assistance.Scopu

Mycoremediation of Tunisian tannery wastewater under non-sterile conditions using Trametes versicolor: live and dead biomasses

Tannery wastewater contains high concentration of pollutants (nitrogen, organic matter, toxic metals, etc.). The present study investigated the efficiency of mycoremediation on the removal of organic and inorganic pollutants and the reduction of the toxicity from a tannery wastewater (TW) using live and dead biomasses of Trametes versicolor under non-sterile conditions. Batch experiments were carried out at the normal pH of the raw TW (8.25) and at pH = 5.5. Monitoring of chemical oxygen demand (COD) reduction, chromium removal (Cr), laccase activity, color and toxicity removals, and the fungal functional groups involved in the mycoremediation was conducted before and after the treatment. The results revealed that COD removal using live biomass was significantly higher (31.2% for pH = 8.25 and 45% for pH = 5.5) than the removal obtained using dead biomass (only 19%). Laccase activity reached a maximum of 7.975 U/L (pH = 8.25) and 20 U/L (pH = 5.5) after 5 days of treatment. Color and Cr removal reached a maximum of 66% and 80%, respectively, for live biomass at pH = 5.5. FTIR spectra revealed the involvement of hydroxyl amino, phospholipids, carboxylic, and carbonyl groups in the elimination of TW pollutants. The phytotoxicity test showed that the decrease in the toxicity levels was significantly higher for live biomass, reaching 44.1% at pH = 5.5 and did not exceed 33% for dead biomass. Overall, this study advocates the potential of TW mycoremediation under non-sterile conditions and the efficiency of live biomass compared to dead biomass in reducing the organic and inorganic pollutants and consequently the toxicity levels in the TW

Optimization of extracellular xylanase production by Sclerotinia sclerotiorum S2 using factorial design

404-409The improvement of xylanase production by Sclerotinia sclerotiorum S2 using a liquid fermentation culture was investigated. The optimized process was divided into three basic steps: (i) evaluating xylanase inducers using different agricultural residues such as wheat bran, oat bran, orange peel and barley bran at 1% final concentration, and also filter paper. Among these, wheat bran showed the maximum activity (2.5 U/ml) at 12 days post-inoculation; (ii) for optimization, we determined the optimal concentration of inducer, the effect of phosphate anion (K₂HPO₄/KH₂PO₄) and culture aeration using a rotary shaker at 100 and 180 rpm. The optimal conditions for these three factors were determined in an experimental panel using factorial data, in which a mathematical model (Minitab software) was fitted; (iii) The optimized culture medium containing a high level of wheat bran (3%) without K₂HPO₄/KH₂PO₄ and submitted to a high agitation (180 rpm/min) increased the xylanase production from 2.5 U/ml to 4 U/ml (1.6-fold)

Localisation des ARNm sur la surface mitochondriale : outil pour le traitement de pathologies rétiniennes dues à des mutations de l'ADN mitochondrial

La distribution spatio-temporelle des ARNm joue un rôle fondamental au cours du développement et de la différenciation cellulaire mais aussi pour permettre la plasticité synaptique. L'adressage d'ARNm à la surface d'organites, en particulier la mitochondrie, est également important pour l'accomplissement des fonctions dans la cellule. Deux séquences sont nécessaires et suffisantes pour localiser un ARNm sur la surface mitochondriale : le MTS (Mitochondrial Targeting Sequence) et le 3'UTR. C'est pourquoi, nous avons utilisé la localisation des ARNm comme un outil pour adresser à la mitochondrie une protéine qui n'est pas normalement importée. Nous avons choisi d'associer aux versions nucléaires des gènes ATP6 et ND1 les séquences d'adressage du gène nucléaire COX10, dont l'ARNm qui se localise exclusivement sur la surface mitochondriale. Cette stratégie consistant à contraindre un ARNm à se localiser sur la surface mitochondriale améliore significativement l'expression allotopique des gènes mitochondriaux examinés

Antibiotic prescribing and outcomes in cancer patients with febrile neutropenia in the emergency department

International audienceINTRODUCTION:The benefit of reducing the time of antibiotic initiation in the emergency department (ED) for neutropenic patients is controversial and the research on the impact of antibiotic adherence to international guidelines in the ED is scarce. We aimed to investigate the effect of antibiotic timing and appropriateness on outcomes in patients with febrile neutropenia (FN) and to assess the performance of the MASCC risk-index to risk-stratify such patients in the ED.METHODS:We prospectively identified patients with FN who presented to our ED and assessed their Multinational Association of Supportive Care in Cancer (MASCC) risk-index. The time to parenteral antibiotic initiation and the appropriateness of the antibiotic regimen according to international guidelines were retrospectively abstracted. The performance of the MASCC risk-index in predicting the absence of complication was assessed with sensitivity, specificity and the area under the receiver operating characteristics curve (AUC). We investigated the effect of the time to antibiotic initiation and the appropriateness of the antibiotic regimen on the outcome (ICU admission or death) by logistic regression analyses.RESULTS:We included 249 patients. Median age was 60 years and 67.9% had hematological malignancies, 26 (10.4%) were admitted to the ICU and 23 (9.8%) died during hospital stay. Among the 173 patients at low risk according to the MASCC risk-index, 56 (32.4%) presented at least one complication including 11 deaths. The MASCC risk-index had a sensitivity and a specificity of 0.78% and 0.43%, respectively, in predicting the absence of complication and the AUC was 0.67. The time to antibiotic initiation in the ED was not associated with the outcome after adjusting for performance status and shock-index. Conversely, an inadequate ED antibiotic regimen was associated with higher ICU admission or death during hospital stay (OR = 3.50; 95% CI = 1.49 to 8.28).CONCLUSION:An inadequate ED antibiotic regimen in patients with FN was significantly associated with higher ICU admission or death during hospital stay

Biochar from olive mill solid waste as an eco-friendly adsorbent for the removal of polyphenols from olive mill wastewater

In Tunisia, olive mill waste water (OMW) is discharged into evaporation ponds where they turn into solid waste (OMSW) and become a serious threat to the environment. This paper addresses for the first time how to valorize OMSW into a biochar (BC) that can be used as an adsorbent aiming at either the recovery or the removal of polyphenols from the OMW. In this work, BC was produced through the pyrolysis of OMSW. Response Surface Methodology (RSM) approach was used for optimization of the process parameters. Analysis of variance revealed that all four parameters (pH, adsorbent dosage, pyrolysis temperature and polyphenols loading) had a significant effect on the adsorption (p<0.05). pH proved to be the most highly significant variable. The nonlinear Freundlich isotherm model was found to better describe the experimental adsorption process (R2=0.9911), while maximum polyphenol adsorption at 30°C was 140.47mg/g. Indeed, OMW is known as a source of natural antioxidant such as Hydroxytyrosol. In this work, hydrxytyrosol proved to have a high adsorption affinity for the BC. Therefore, adsorption using BC is an appropriate technique that maximizes the recuperation of hydroxytyrosol. After detoxification, OMW is invested for a variety of applications.This study was supported by the project ARIMNet2 PYRODIGEST, which is funded through the ARIMNet2 2017 Joint Call by the MHESRT funding agency. The ARIMNet2 (ERANET) program received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 618127

Nuclear expression of mitochondrial ND4 leads to the protein assembling in complex I and prevents optic atrophy and visual loss

Leber hereditary optic neuropathy is due to mitochondrial DNA mutations; in â¼70% of all cases, a point mutation in the mitochondrial NADH dehydrogenase subunit 4, ND4, gene leads to central vision loss. We optimized allotopic expression (nuclear transcription of a gene that is normally transcribed inside the mitochondria) aimed at designing a gene therapy for ND4; its coding sequence was associated with the cis-acting elements of the human COX10 mRNA to allow the efficient mitochondrial delivery of the protein. After ocular administration to adult rats of a recombinant adeno-associated viral vector containing the human ND4 gene, we demonstrated that: (i) the sustained expression of human ND4 did not lead to harmful effects, instead the human protein is efficiently imported inside the mitochondria and assembled in respiratory chain complex I; (ii) the presence of the human protein in the experimental model of Leber hereditary optic neuropathy significantly prevents retinal ganglion cell degeneration and preserves both complex I function in optic nerves and visual function. Hence, the use of optimized allotopic expression is relevant for treating mitochondrial disorders due to mutations in the organelle genome