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The aim of this work was to isolate indigenous PAH degrading-fungi from petroleum contaminated soil and exogenous ligninolytic strains from decaying-wood, with the ability to secrete diverse enzyme activity. A total of ten ligninolytic... more
The aim of this work was to isolate indigenous PAH degrading-fungi from petroleum contaminated soil and exogenous ligninolytic strains from decaying-wood, with the ability to secrete diverse enzyme activity. A total of ten ligninolytic fungal isolates and two native strains, has been successfully isolated, screened and identified. The phylogenetic analysis revealed that the indigenous fungi (KBR1 and KB8) belong to the genus Aspergillus niger and tubingensis. While the ligninolytic exogenous PAH-degrading strains namely KBR1-1, KB4, KB2 and LB3 were affiliated to different genera like Syncephalastrum sp, Paecilomyces formosus, Fusarium chlamydosporum, and Coniochaeta sp., respectively. Basis on the taxonomic analysis, enzymatic activities and the hydrocarbons removal rates, single fungal culture employing the strain LB3, KB4, KBR1 and the mixed culture (LB3+KB4) were selected to be used in soil microcosms treatments. The Total petroleum hydrocarbons (TPH), fungal growth rates, BOD5/...
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The main purpose of this study was to degrade total petroleum hydrocarbons (TPHs) from contaminated soil in batch microcosm reactors. Native soil fungi isolated from the same petroleum-polluted soil and ligninolytic fungal strains were... more
The main purpose of this study was to degrade total petroleum hydrocarbons (TPHs) from contaminated soil in batch microcosm reactors. Native soil fungi isolated from the same petroleum-polluted soil and ligninolytic fungal strains were screened and applied in the treatment of soil-contaminated microcosms in aerobic conditions. The bioaugmentation processes were carried out using selected hydrocarbonoclastic fungal strains in mono or co-cultures. Results demonstrated the petroleum-degrading potential of six fungal isolates, namely KBR1 and KBR8 (indigenous) and KBR1-1, KB4, KB2 and LB3 (exogenous). Based on the molecular and phylogenetic analysis, KBR1 and KB8 were identified as Aspergillus niger [MW699896] and tubingensis [MW699895], while KBR1-1, KB4, KB2 and LB3 were affiliated with the genera Syncephalastrum sp. [MZ817958], Paecilomyces formosus [MW699897], Fusarium chlamydosporum [MZ817957] and Coniochaeta sp. [MW699893], respectively. The highest rate of TPH degradation was rec...
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The search for novel microorganisms able to degrade olive mill wastewaters (OMW) and withstand the toxic effects of the initially high phenolic concentrations is of great scientific and industrial interest. In this work, the possibility... more
The search for novel microorganisms able to degrade olive mill wastewaters (OMW) and withstand the toxic effects of the initially high phenolic concentrations is of great scientific and industrial interest. In this work, the possibility of reducing the phenolic content of OMW using new isolates of fungal strains (Coriolopsis gallica, Bjerkandera adusta, Trametes versicolor, Trichoderma citrinoviride, Phanerochaete chrysosporium, Gloeophyllum trabeum, Trametes trogii, and Fusarium solani) was investigated. In vitro, all fungal isolates tested caused an outstanding decolorization of OMW. However, C. gallica gave the highest decolorization and dephenolization rates at 30 % v/v OMW dilution in water. Fungal growth in OMW medium was affected by several parameters including phenolic compound concentration, nitrogen source, and inoculum size. The optimal OMW medium for the removal of phenolics and color was with the OMW concentration (in percent)/[(NH4)2SO4]/inoculum ratio of 30:6:3. Under these conditions, 90 and 85 % of the initial phenolic compounds and color were removed, respectively. High-pressure liquid chromatography analysis of extracts from treated and untreated OMW showed a clear and substantial reduction in phenolic compound concentrations. Phytotoxicity, assessed using radish (Raphanus sativus) seeds, indicated an increase in germination index of 23-92 % when a 30 % OMW concentration was treated with C. gallica in different dilutions (1/2, 1/4, and 1/8).
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Response surface methodology (RSM) was applied to optimize the decolourization of 3 dyes belonging to 3 dye families such as reactive black 5 (diazoic), indigo carmine (indigoid) and aniline blue (anthraquinonic). Crude laccase from... more
Response surface methodology (RSM) was applied to optimize the decolourization of 3 dyes belonging to 3 dye families such as reactive black 5 (diazoic), indigo carmine (indigoid) and aniline blue (anthraquinonic). Crude laccase from Trametes trogii and the laccase-mediator 1-hydroxybenzotriazole (HBT) were used in this study. Box-Behnken design using RSM with six variables namely pH, temperature, enzyme concentration, HBT concentration, dye concentration and incubation time was used in this study to optimize significant correlation between the effects of these variables on the decolourization of reactive black 5 (RB5), indigo carmine (IC) and aniline blue (AB). The optimum of pH, temperature, laccase, HBT, RB5 and reaction time were 4.5, 0.5 U ml(-1), 0.5 mM, 100 mg ml(-1) and 150 min respectively, for a maximum decolourization of RB5 (about 92.92% ± 7.21). Whereas, the optimum decolourization conditions of both IC (99.76% ± 7.75) and AB (98.44% ± 10) were: pH 4.5, temperature of 45 °C, enzyme concentration of 0.1 U ml(-1) and 0.5 U ml(-1), HBT concentration of 0.9 mM and 0.5 mM, dye concentration of 60 mg l(-1) and reaction time of 150 and 90 min, respectively. The experimental values were in good agreement with the predicted ones and the models were highly significant, the correlation coefficient (R(2)) being 0.864, 0.663 and 0.776 for RB5, IC and AB, respectively. In addition, when the kinetic parameters for the three dyes decolourization were calculated according to Hannes-Wolf plot, the following values were obtained: Km of 268.4, 47.94 and 44.64 mg l(-1) then V(max) of 35.58, 10.43 and 9.23 mg l(-1) min for the RB5, IC and AB decolourizations by laccase, respectively.
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Abstract Synthetic dyes are extensively used in a number of industries, such as textile dyeing. Due to their low biodegradability, they cause serious environmental pollution. Thus, in the present paper a partially-purified acid fungal... more
Abstract Synthetic dyes are extensively used in a number of industries, such as textile dyeing. Due to their low biodegradability, they cause serious environmental pollution. Thus, in the present paper a partially-purified acid fungal laccase from the white-rot basidiomycete Coriolopsis gallica was entrapped into calcium alginate beads and applied to the decolorization of different synthetic dyes. Effects of immobilization conditions such as alginate concentration, CaCl2 concentration and the ratio enzyme/alginate (E/A) on the loading efficiency and immobilization yield were investigated. The optimal conditions for C. gallica laccase immobilization into Ca-alginate beads were 2% (w/v) sodium alginate, 2% (w/v) CaCl2, and 1:4 E/A (v/v). It was also found that laccase stability to pH and temperature increased after immobilization. Both the free and immobilized laccase alone showed a high efficiency to decolorize the anthraquinone dye Remazol Brilliant Blue R (RBBR) while a low decolorization yield was observed for the diazo dyes Reactive Black 5 (RB5) and Bismark Brown R (BBR) and the metal textile dye Lanaset Grey G (LG). The addition of the redox mediator 1-hydroxybenzotriazole (HBT) to the decolorization reaction increased significantly dye removal. The immobilized laccase retained 70% of its activity after four successive decolorization cycles except for BBR (51.2%). The results obtained showed that the immobilized laccase from C. gallica has potential for its application in dyestuff treatment.
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The aim of the present study was to evaluate the phytotoxicity of olive mill wastewater (OMW) after being treated by the white-rot fungus Coriolopsis gallica. For this, the effect of irrigation with treated OMW (TOMW) and untreated OMW... more
The aim of the present study was to evaluate the phytotoxicity of olive mill wastewater (OMW) after being treated by the white-rot fungus Coriolopsis gallica. For this, the effect of irrigation with treated OMW (TOMW) and untreated OMW (UOMW) on tomato plants (Lycopersicon esculentum) for 3 weeks was studied. The control plants were irrigated with distilled water. Agronomic tests were performed in pot experiments in a greenhouse using the randomized complete block (RCB) experimental design. The relative leaf height (RLH), as a morphological parameter, and the content of total phenols in the roots and total chlorophyll [Cha + Chb] and reducing sugars in the leaves, as physiological parameters, were selected as responses of the experimental design. The results obtained showed that [Cha + Chb] in the leaves of tomato growth under TOMW was enhanced by 36.3 and 19.4 % compared to the plant growth under UOMW and to the controls, respectively. Also, reducing sugar concentrations were close...
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In this paper we studied the ability of four Tunisian-isolated fungi (i.e. Coriolopsis gallica, Bjerkandera adusta, Trametes versicolor and Trametes trogii) immobilized into Ca-alginate beads to decolorize the metal textile dye Lanaset... more
In this paper we studied the ability of four Tunisian-isolated fungi (i.e. Coriolopsis gallica, Bjerkandera adusta, Trametes versicolor and Trametes trogii) immobilized into Ca-alginate beads to decolorize the metal textile dye Lanaset Grey G (LG). The effect of different operational conditions, such as initial dye concentration, temperature, pH, beads/medium ratio and agitation, on dye decolorization by the immobilized fungi was investigated. Maximal decolorization percentages of 88.7%, 89.3%, 82.1% and 81.3% for C. gallica, B. adusta, T. versicolor and T. trogii were attained, respectively, when operating at an initial LG concentration of 150 mg/L, pH values of 5.0-6.0, temperatures of 40-45 °C and a beads/medium ratio of 20% (w/v) in static conditions after 72 h of incubation. Subsequently, the re-usability of the immobilized fungi was evaluated. After three decolorization cycles, the decolorization percentage of free cell cultures dropped to values below 36%, while decolorization percentages of about 75%, 70%, 60% and 68% were obtained by the immobilized cultures of C. gallica, B. adusta, T. versicolor and T. trogii, respectively.
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A white-rot basidiomycete, isolated from decayed acacia wood (from Northwest of Tunisia) and identified as Trametes sp, was selected in a broad plate screening because of its ability to decolorize and dephenolize olive oil mill wastewater... more
A white-rot basidiomycete, isolated from decayed acacia wood (from Northwest of Tunisia) and identified as Trametes sp, was selected in a broad plate screening because of its ability to decolorize and dephenolize olive oil mill wastewater (OMW) efficiently. The major laccase was purified and characterized as a monomeric protein with apparent molecular mass of 61 kDa (SDS-PAGE). It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 4.0 and a temperature of 60 °C. The purified laccase is stable at alkaline pH values. The enzyme retained 50 % of its activity after 90 min of incubation at 55 °C. Using ABTS, this laccase presented K m and V max values of 0.05 mM and 212.73 μmoL min(-1) mg(-1), respectively. It has shown a degrading activity towards a variety of phenolic compounds. The purified laccase was partially inhibited by Fe(2+), Zn(2+), Cd(2+) and Mn(2+), while Cu(2+) acted as inducer. EDTA (10 mM) and NaN3 (10 mM) were found to complete...
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The aim of this work was to determine the optimal conditions for the decolorization and the detoxification of two effluents from a textile industry-effluent A (the reactive dye bath Bezactive) and effluent B (the direct dye bath... more
The aim of this work was to determine the optimal conditions for the decolorization and the detoxification of two effluents from a textile industry-effluent A (the reactive dye bath Bezactive) and effluent B (the direct dye bath Tubantin)-using a laccase mediator system. Response surface methodology (RSM) was applied to optimize textile effluents decolorization. A Box-Behnken design using RSM with the four variables pH, effluent concentration, 1-hydroxybenzotriazole (HBT) concentration, and enzyme (laccase) concentration was used to determine correlations between the effects of these variables on the decolorization of the two effluents. The optimum conditions for pH and concentrations of HBT, effluent and laccase were 5, 1 mM, 50 % and 0.6 U/ml, respectively, for maximum decolorization of effluent A (68 %). For effluent B, optima were 4, 1 mM, 75 %, and 0.6 U/ml, respectively, for maximum decolorization of approximately 88 %. Both effluents were treated at 30 °C for 20 h. A quadratic model was obtained for each decolorization through this design. The experimental and predicted values were in good agreement and both models were highly significant. In addition, the toxicity of the two effluents was determined before and after laccase treatment using Saccharomyces cerevisiae, Bacillus cereus, and germination of tomato seeds.
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A highly alkaline trypsin from the intestine of Grey triggerfish (Balistes capriscus), with high activity at low temperature, was purified and characterised. The enzyme was purified to homogeneity using acetone precipitation, Sephadex... more
A highly alkaline trypsin from the intestine of Grey triggerfish (Balistes capriscus), with high activity at low temperature, was purified and characterised. The enzyme was purified to homogeneity using acetone precipitation, Sephadex G-100 gel filtration and Mono Q-...