Background: Constructed wetlands are systems designed based on the utilization of natural processes, including vegetation, soil, and their associated microbial assemblage to assist in treating different types of wastewater. Methods: Two local Appalachian plants (Louis latifolia and Phragmites australis) were planted into small-scale constructed wetlands to treat domestic wastewater in the North of Iran. The influent wastewater and the effluent from each wetland were sampled daily for 120 days. Experiments were conducted based on the mean +/- standard deviation (SD) by analysis of variance (ANOVA). Results: It was found that nitrate, phosphate, fecal and total coliforms were reduced by 84.4%, 94.4%, 96.3%, 93.9% for P. australis and 73.3%, 64.0%, 94.4%, 92.1% for L. latifolia, respectively. Conclusion: According to the results, by using the HF-CW technology with L. latifolia and P. australis plants, the treated wastewater fully meets the wastewater discharge parameters of WHO standards.

This paper describes the production of ligninolytic enzymes by the white-rot fungus Pleurotus sajor caju under solid-state fermentation conditions using a cost-effective medium consisting of agro-industrial wastes. From the different agro-industrial wastes tested (i.e. orange, banana, mango and cantaloupe peels), banana peels led to the highest manganese-dependent peroxidase (MnP) activity (6.3 U/mL on the 10 day). MnP from banana peel cultures was purified and applied to the discoloration of the azo dye Congo Red (CR). The optimum temperature, pH and enzyme concentration for maximum discoloration (i.e. 95% in 1 h) were found to be 35A degrees C, 4.0, and 1.4 U/mL, respectively. In addition, the phytotoxicity (with respect to Sorghum vulgare and Phaseolus radiatus seeds) of CR was considerably reduced after the treatment of plant material with MnP produced by P. sajor caju. The products obtained after discoloration of CR were characterized using GC/MS as 8-amino naphthol 3-sulfonic acid, 3-hydroperoxy 8-nitrosonaphthol, p-p'-dihydroxybiphenyl. Therefore, this approach holds promise for the production and application of MnP from P. sajor caju on a larger scale.

White-rot-fungi (WRF) are the only organisms able to degrade the whole wood components (i.e. lignin, cellulose and hemicellulose). This ability is due to the secretion of extracellular nonspecific ligninolytic enzymes during their secondary metabolism usually triggered by nutrient exhaustion. The non-specificity of these enzymes enables them to transform a great variety of recalcitrant and hazardous pollutants such as polycyclic aromatic hydrocarbons (PAHs), pesticides, fuels, alkanes, polychlorinated biphenyls (PCBs), explosives and synthetic dyes. In addition, their extracellular nature allows WRF to access non-polar and insoluble compounds. This makes WRF very appealing for their application to different industrial and biotechnological processes. Also, new potential commercial products and processes from the fungal treatment of lignocellulosic materials may arise. The implementation of such applications would contribute to the establishment of a more sustainable industry and the development of a circular economy.

Polychlorinated aromatic compounds, including pentachlorobenzenes and hexachlorobenzenes, are recalcitrant industrial pollutants that cause adverse effects on living cells. In this paper, the isolation of Pseudomonas fluorescens species with high resistance to pentachlorobenzene (PeCB) is reported. It was found that, in contrast to its slightly negative effect on P. fluorescens growth, PeCB readily inhibited the cell growth of Serratia spp. and Escherichia coli strains, thus indicating that inhibition of bacterial growth by PeCB is species-dependent. Analysis of a P. fluorescens isolate revealed that the exposure to PeCB induced production of reactive oxygen species and led to an increase in the level of alkyl hydroperoxide reductase C (AhpC), an important enzyme enhancing the cell tolerance to organic hydroperoxides usually accumulated under oxidative stress. The putative mechanism conferring PeCB resistance to P. fluorescens and the potential use of P. fluorescens in bioremediation are discussed.

In this study, the potential of natural pumice (NP) and iron-coated pumice stone (Fe-CP) as novel low-cost adsorbents to remove ethidium bromide (EtBr) from aqueous solutions was investigated. The operational parameters affecting removal efficiency and adsorption capacity such as adsorbent dose, initial EtBr concentration, pH, and contact time were studied in order to maximize EtBr removal. The maximum amount of adsorbed EtBr (q(m)) using NP and Fe-CP was 40.25 and 45.08mgg(1), respectively. It was found that EtBr adsorption followed the Freundlich isotherm model and fitted the pseudo-second-order kinetics equation for both adsorbents. In addition, the experimental system could be easily modeled by artificial neural network calculations.

In the present paper, the removal of ethidium bromide (EtBr) from aqueous solutions in a batch system using natural (NP) and aluminium-coated pumice (ACP) as alternative low-cost adsorbents was investigated. The maximum adsorption capacity, q(m) (mg/g) was 58.82 and 76.92 mg/g for NP and ACP, respectively, operating at an initial pH of 8, an adsorbent dose of 8 g/L, a contact time of 210 min and an initial EtBr concentration of 30 mg/L. The equilibrium data of both adsorbents fitted the Freundlich isotherm model, indicating the heterogeneity of the adsorbent surface. In addition, the adsorption rate of both adsorbents was well described by the pseudo-second-order kinetics model. This indicated chemisorption was the rate -controlling step of the adsorption process which occurred by ion exchange. Within the performed study, a three-layer artificial neural network (ANN) model was also developed to predict the efficiency of EtBr removal. Computational results clearly demonstrated that the ANN model was able to predict the combined effect of initial pH, adsorbent dose, contact time and initial EtBr concentration on the adsorption efficiency with a very high determination coefficient (R-2 = 0.998) and a low relative error (RE = 0.037). (C) 2015 Elsevier B.V. All rights reserved.

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 closed to those of the control plants, ranging from 0.424 to 0.678 g/L for the different dilutions tested. However, the plants irrigated with UOMW showed lower reducing sugar concentrations ranging from 0.042 to 0.297g/L. The optimum RLH (0.537) was observed in the plants irrigated with TOMW diluted at (1:4), this value being higher than that observed in the controls (0.438). Our study proved that the irrigation with TOMW significantly improved tomato growth and photosynthesis activity over those irrigated with UOMW. Optimization of TOMW as a fertilizer was obtained for a dilution of 1:4. From the obtained results, it can be concluded that OMW treated by C. gallica holds potential to be used as a fertilizer for tomato plants.

Azinphos-methyl and chlorpyrifos are the organophosphorous pesticides which pose serious threats to the environment including their detrimental effect on humans and, therefore, their removal from the environment is a must. Hence, in the present paper the ultrasound technique was applied to remove the above-mentioned hazardous compounds. For this, the effect of influential parameters such as pH, initial pesticide concentration, frequency, electric power and treatment time on the ultrasound degradation of azinphos-methyl and chlorpyrifos was well investigated and elucidated. The results obtained showed that azinphos-methyl and chlorpyrifos were effectively and rapidly degraded by the ultrasound technique. Thus, the operating optimal conditions (initial pH 9, initial pesticide concentration 1 mg/L, frequency 130 kHz, electric power 500 Wand treatment time 20 min) lead to a degradation of 78.50% for azinphos-methyl and of 98.96% for chlorpyrifos with in 20 min of contact time. Two multiple regression-based equations were derived to describe the degradation process of the pesticides by the ultrasound treatment. The result of this study showed that the-polynomial equations satisfactorily described the behavior of the present process for various operating conditions. (C) 2016 Elsevier B.V. All rights reserved.

Background: Laccases are multicopper oxidases with high potential for environmental and industrial applications. Low-cost laccase production could be achieved by solid state fermentation on agro-industrial by-products. Methods: A number of agro-industrial solid wastes were tested as support-substrate for laccase production by Coriolopsis gallica under solid-state fermentation (SSF) conditions. Response surface methodology (RSM) was used to optimize the medium composition for laccase production. Initial screening by Plackett-Burman design was performed to select the major variables out of 20 tow medium components fellowing this Central composite design (CCD) was employed to optimize the level of the selected variables. Results: Sawdust waste was shown to be the best support-substrate for laccase production by the C. gallica. Peptone as source of organic nitrogen, Cd2+ as laccase inducer and liquid/solid (L/S) ratio were found to have significant effects on laccase production. Operating at optimum concentrations of the most significant variables (peptone, 4.5 g L-1, L/S ratio, 5.0 and Cd+2 1.0 mM) extracellular laccase activity was enhanced from 1480 U L-1 (60.5 U g(-1)), to 4880 U L-1 (200 U g(-1)) which meant a 3.2-fold increase in laccase activity. On the other hand, sawdust waste was studied as a low cost adsorbent to remove the azo dyes Reactive Black 5 (RB5) and Acid Orange 51 (AO51). Decolorization percentages around 67 and 75 % were obtained in 24 h for RB5 and AO51, respectively. Conclusion: When used as a support substrate, sawdust yielded the highest laccase production which was increased 3.2 times using RMS optimization.

Endogenous bacterial strains possessing a high bisphenol A (BPA)-tolerance/degradation activity were isolated from different outlets of petrochemical wastewater in Iran using the enrichment cultivation approach. Two bacterial isolates with high efficiency for BPA degradation in basal medium and petrochemical wastewater were identified as Enterobacter gergoviae strain BYK-7 and Klebsiella pneumoniae strain BYK-9 using morphology, 16s rDNA analysis and MALDI-TOF mass spectrometry systems. Due to the pathogenicity of K. pneumoniae, the E. gergoviae strain was selected for further studies. This strain with very high BPA tolerance (up to 2000 mg L-1) degraded 23.10 +/- 0.126 mg L-1 BPA in basal medium, 31.35 +/- 4.05 mg L-1 BPA in petrochemical wastewater and 53.50 +/- 0.153 mg L-1 BPA in nutritious medium within 8, 72 and 48 h, respectively. Biostimulation by mineral salts and ethanol was effective in the BPA-degradation activity of the E. gergoviae. In addition, recombinant E. gergoviae [pBRbisd] was able to degrade 45.02 +/- 0.334 mg L-1 BPA in basal medium within 48 h. These results point out this strain as a very promising organism for BPA removal in industrial wastewater.

Graphene-based materials appear as a suitable answer to the demand for novel nanostructured materials for effective nanobiocatalytic systems design. In this work, a design of stable and efficient nanobiocatalysts made of enzyme laccase immobilized on composite hydrogels [reduced graphene oxide (rGO)/polymer] is presented. The composite hydrogel supports were synthesized by self-assembly of graphene oxide nanoplatelets in the frame of a polymer latex matrix, where the polymer nanoparticles were adsorbed onto the GO surface, creating hybrid nanoplatelets. These hybrids self-assembled when ascorbic acid was added as a GO reducing agent and formed three-dimensional porous structures, greatly swollen with water, e.g., the composite hydrogels. The hydrogels were used as a support for covalent immobilization of the laccase. The performance of the nanobiocatalysts was tested in the oxidative degradation of the recalcitrant synthetic dye Remazol Brilliant Blue R in aqueous solutions. The biocatalysts showed strong dye discoloration ability and high stability as they preserved their catalytic action in four successive batches of dye degradation. The presented biocatalysts offer possibilities for overcoming the main disadvantages of the enzyme catalysts (fragile nature, high cost, and high loading of the enzyme), which would lead to a step forward toward their industrial application.

Activated carbons prepared from walnut and poplar woods are used as economical adsorbents for the rapid removal and fast adsorption of Acid Red 18 dye from the aqueous solutions; the kinetics, isotherm and thermodynamics studies of the process were well investigated and elucidated. The adsorption phenomenon may be possibly attributed to the formation of various binding bonds between the activated carbons, developed from the poplar and walnut woods, surface and the dye molecules; adsorption may firstly take place on the external surface of the developed adsorbent i.e. activated carbon developed from the walnut and poplar wood particles, where the attached functional groups play a crucial role in the rapid removal and fast adsorption. Secondly, adsorption may take place on the entire surface, which leads to a uniform distribution of adsorbed Acid Red 18 molecules onto the developed adsorbents. Forces that are responsible for the main adsorption mechanism are pi-pi attraction between Acid Red 18 dye molecules and the C=C bonds of the developed adsorbents. Consequently, at least three types of adsorption sites might occur on the adsorbent surface; these are basal plane, edge plane and micropores. Neither pseudo-first order kinetic model nor pseudo-second order kinetic model was able to describe the adsorption process of AR18 molecules onto the activated carbon from poplar wood. (C) 2015 Elsevier B.V. All rights reserved.

Rapid removal of the Acid Orange 7 (AO7) from aqueous solutions using natural pumice (NP) and Fe-coated pumice (Fe-CP) as low-cost adsorbents was well investigated and elucidated. The impact of several influential parameters such as initial pH, initial AO7 concentration and contact time on the adsorption of AO7 removal was studied and optimized. The good agreement of adsorption equilibrium data and analysis of isotherms with the Freundlich isotherm proved that it is the best fitted adsorption isotherm model for the depicting the AO7 adsorption on both the developed adsorbents, which clearly indicates the heterogeneity of the adsorbent surface. The maximum adsorption capacities for the NP and Fe-CP were found to be 15.56 and 27.68 mg/g, respectively. The rate of adsorption followed the pseudo-second-order kinetic model. (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

The development of a solid-phase biocatalyst based on the reversible covalent immobilization of laccase onto thiol-reactive supports (thiolsulfinate-agarose [TSI-agarose]) was performed. To achieve this goal, laccase-producing strains isolated from Eucalyptus globulus were screened and white rot fungus Trametes villosa was selected as the best strain for enzyme production. Reduction of disulfide bonds and introduction of de novo thiol groups in partially purified laccase were assessed to perform its reversible covalent immobilization onto thiol-reactive supports (TSI-agarose). Only the thiolation process dramatically improved the immobilization yield, from 0% for the native and reduced enzyme to 60% for the thiolated enzyme. Mild conditions for the immobilization process (pH 7.5 and 4 degrees C) allowed the achievement of nearly 100% of coupling efficiency when low loads were applied. The kinetic parameters, pH, and thermal stabilities for the immobilized biocatalyst were similar to those for the native enzyme. After the first use and three consecutives reuses, the insoluble derivative kept more than 80% of its initial capacity for decolorizing Remazol Brilliant Blue R, showing its suitability for color removal from textile industrial effluents. The possibility of reusing the support was demonstrated by the reversibility of enzyme-support binding.

Fungal immobilization is an interesting topic in enzyme production and bioprocess development. The properties of graphene (i.e. large surface area, hydrophobicity), together with the possibility of producing it at low cost and with tailor-made properties, make this popular material worthy of investigation as a support for fungal immobilization. In the present paper, 3D-organized structures of reduced graphene oxide (rGO) in hydrogels and their dried derivatives (xerogels) were synthesized, characterized and investigated as potential supports for the immobilization of the white-rot fungus Trametes pubescens. It was found that the morphology of the hydrogels and xerogels was not influenced by the synthesis conditions; however the 3D structure was preserved after drying and formation of xerogels. Both, hydrogels and xerogels have been shown to be suitable supports for the immobilization of T. pubescens. Additionally, xerogels promoted increased laccase activities and maximum activity values of about 20 +/- 1 U/mL were attained. These activities were much higher than those obtained with other well-known inert supports. Nevertheless, no relationship between support morphology and productivity was found. The encouraging results obtained have paved the way for the development of novel graphene-based supports for microorganism immobilization.

The potential of using pumice and walnut wood activated carbon as low-cost adsorbents for the removal of the diazo dye Reactive Black 5 (RB5) from aqueous solutions was investigated. The Langmuir isotherm fit to the data specified the presence of two different natures of adsorption sites with different binding energies on the AC-W surface. Kinetic modelling showed that the adsorption behaviour and mechanism of RB5 for both adsorbents is believed to happen via surface adsorption followed by diffusion into the pores of the AC-W and pumice. The main adsorption mechanisms are hydrogen bonding, electrostatic bonding and n-pi interactions. (C) 2013 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

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 A degrees 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.

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 degrees 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. (C) 2013 Elsevier Ltd. All rights reserved.

Laccase from the white-rot fungus Pleurotus florida, produced under solid-state fermentation conditions, was used for the decolorization of reactive dye Remazol Brilliant Blue R (RBBR). RBBR was decolorized up to 46% by P. florida laccase alone in 10min. In the presence of N-hydroxybenzotriazole (HBT), the rate of decolorization was enhanced 1.56-fold. Central composite design of response surface methodology with four variables namely, dye, enzyme, redox mediator concentrations, and time at five levels was applied to optimize the RBBR decolorization. The predicted optimum level of variables for maximum RBBR decolorization (87%) was found to be 52.90mgL(-1) (RBBR), 1.87UmL(-1) (laccase), 0.85mM (HBT), and 7.17min (time), respectively. The validation results showed that the experimental value of RBBR decolorization (82%) was close to the predicted one. The disappearance of C-N and C-X groups, and a small shift in N-H groups in Fourier-transform infra red (FTIR) spectroscopy confirms the degradation of RBBR chromophore by laccase enzyme. The phytotoxicity of RBBR was considerably reduced after the treatment with laccase. RBBR decolorization kinetics; K-m and V-max were calculated to be 145.82mgL(-1) and 24.86mgL(-1)min, respectively.

The production of neomycin by the actinomycete Streptomyces fradiae, under semi-solid-state fermentation conditions was the main subject of this study. Two supports (nylon sponge and orange peelings) were tested in order to determine the most suitable one for the production of neomycin by the above-mentioned microorganism. Nylon sponge led to the highest neomycin production, reaching a maximum value of 13,903 mu g/mL on the 10th day of cultivation. As a control, the same experiment was performed under submerged fermentation (SmF) conditions, without solid support. Here the production of neomycin by S. fradiae was about 55-fold lower (i.e. 250 mu g/mL) than that obtained for SSF. (C) 2013 Elsevier B.V. All rights reserved.

Cubes of nylon sponge, cubes of polyurethane foam (PUF), cuttings of stainless steel sponges and the commercial carriers Kaldnes (TM) K1 were tested as inert supports for laccase production by the white-rot fungus Trametes pubescens under semi-solid-state fermentation conditions. The cultures operating with Kaldnes (TM) K1 led to the highest laccase activity (3667 U/I). In addition this support could be re-utilised, making the whole process more economical. Subsequently, the decolouration of simulated textile wastewater (STW) by T. pubescens grown on the different tested supports under semi-solid-state fermentation conditions was studied. Decolouration percentages around 66-80% were obtained in 96h. It was found that STW decolouration was due to two mechanisms: laccase action (biodegradation) and adsorption onto fungal mycelium, save for the PUF cultures in which decolouration was mainly due to adsorption onto the support. Further, the decolouration of STW by Kaldnes (TM) K1 cultures in three successive batches of 96 h each was studied. Decolouration percentages of 51.3, 70.0 and 69.8%, were attained for each batch, respectively. (C) 2012 Elsevier B.V. All rights reserved.

This study investigates pentachlorophenol (PCP) adsorption by the white-rot fungus Anthracophyllum discolor in a fixed-bed column reactor. PCP adsorption at different concentrations (20, 30, and 50 mg L-1) and pH values (5.0, 5.5, and 6.0) was determined and modeled using the Thomas model. Fourier transform infrared spectroscopy (FTIR) was used to identify functional groups of biomass that may participate in the interaction of PCP. The biosorption capacity of A. discolor was pH-dependent, and the PCP adsorbed increased with the decrease in the pH solution. Acid pH values of the influent gave an increase in saturation time in all PCP concentrations. By contrast, the increase in PCP concentration caused that the binding sites were filled quickly, resulting in a decrease in saturation time. The Thomas model was found suitable for describing the entire dynamic of the column with respect to the PCP concentration and pH of the solution. FTIR results showed that amines, carboxylates, alkanes, and C-O groups might participate in the PCP adsorption on the biomass surface. It was concluded that A. discolor biomass was a good adsorbent for PCP removal from influent with mainly acidic pH.

Ligninolytic enzyme complexes are involved in lignin degradation. Among them laccases are outstanding because they use molecular oxygen as a co-substrate instead of hydrogen peroxide as used by peroxidases. Bacterial laccase of Bacillus genus was first reported in Claus and Filip (Microbiol Res 152:209-216, 1997), since then more bacterial laccases have been found. In this research, laccase-producing bacteria were screened from pulp and paper industry wastewater, bagass and sugarcane rhizosphere. Nutrient agar medium containing 0.5 mM of guaiacol was used. It was observed that the laccase-producing strains developed brown colour from which 16 strains of Bacillus were identified. One of the isolated strains was identified as Bacillus subtilis WPI based on the results of biochemical tests and 16S rDNA sequence analysis. This strain showed laccase-like activity towards the oxidizing substrates ABTS and guaiacol. In this study guaiacol was used as the substrate of laccase activity assay. For determination of laccase activity of this isolate guaiacol was used as a substrate of assay for the first time in this study. SDS-PAGE and Native-PAGE confirmed the presence of laccase.

The in vivo biodegradation of the diazo dye Reactive Black 5 (RBS) by Phanerochaete chrysosporium immobilised on cubes of nylon sponge and on sunflower-seed shells (SS) in laboratory-scale bioreactors was investigated. The SS cultivation led to the hest results with a decolouration percentage of 90.3% in 72 h for an initial RB5 concentration of 100 mg/L. It was found that the addition of 0.4 mM veratryl alcohol (VA) into the medium considerably increased the decolouration rate in SS cultivation. However, the addition of VA had no effect in the nylon cultivation. Thin layer chromatography (TLC) revealed that RB5 was transformed into one metabolite after 24 h. UV-vis spectroscopy and Fourier Transform Infrared (FT-IR) also confirmed the biodegradation of RB5. Toxicity of RB5 solutions before and after fungal treatment was assayed using Sinorhizobium meliloti as a sensitive soil microorganism. P. chrysosporium transformed the toxic dye RB5 into a non-toxic product. (C) 2011 Elsevier Ltd. All rights reserved.

In this paper the cost of producing the enzyme laccase by the white-rot fungus Trametes pubescens under both submerged (SmF) and solid-state fermentation (SSF) conditions was studied. The fungus was cultured using more than 45 culture medium compositions. The cost of production was estimated by analyzing the cost of the culture medium, the cost of equipment and the operating costs. The cost of the culture medium represented, in all cases, the highest contribution to the total cost, while, the cost of equipment was significantly low, representing less than 2% of the total costs. The cultivation under SSF conditions presented a final cost 50-fold lower than the one obtained when culturing under SmF conditions at flask scale. In addition, the laccase production under SSF conditions in tray bioreactors reduced the final cost 4-fold compared to the one obtained under SSF conditions at flask scale, obtaining a final price of 0.04 cent (sic)/U. (C) 2011 Elsevier Ltd. All rights reserved.

Here we propose a software for the estimation of the occupied area and volume of fungal cultures. This software was developed using a Matlab platform and allows analysis of high-definition images from optical, electronic or atomic force microscopes. In a first step, a single hypha grown on potato dextrose agar was monitored using optical microscopy to estimate the change in occupied area and volume. Weight measurements were carried out to compare them with the estimated volume, revealing a slight difference of less than 1.5%. Similarly, samples from two different solid-state fermentation cultures were analyzed using images from a scanning electron microscope (SEM) and an environmental SEM (ESEM). Occupied area and volume were calculated for both samples, and the results obtained were correlated with the dry weight of the cultures. The difference between the estimated volume ratio and the dry weight ratio of the two cultures showed a difference of 10%. Therefore, this software is a promising non-invasive technique to determine fungal biomass in solid-state cultures.

In this paper, we studied the laccase production and the growth morphology of different white-rot fungi, i.e. Pleurotus ostreatus, Trametes pubescens, Cerrena unicolor and Trametes versicolor, cultured under semi-solid-state fermentation conditions using wheat bran flakes as a natural low-cost support substrate. Trametes versicolor exhibited the highest laccase activity per gram of total dry matter, followed by P. ostreatus (63.5 and 58.2 U g-1, respectively). In addition, they showed a time profile of laccase production that was quite similar. Growth morphology was studied using environmental microscopic images and analyzed by discrete Fourier transformation-based software to determine the mean diameter of the hyphae, the number of hypha layers and the global micromorphology. The four strains exhibited different micromorphologies of growth. Pleurotus ostreatus presented narrow hyphae, which formed many thick clumps, T. pubescens and T. versicolor showed clumps of different sizes and C. unicolor showed thick hyphae that formed larger clumps, but in less amounts.

Undergraduate students of biotechnology became familiar with several aspects of bioreactor operation via the production of xanthan gum, an industrially relevant biopolymer, by Xanthomonas campestris bacteria. The xanthan gum was extracted from the fermentation broth and the yield coefficient and productivity were calculated.

Laccase production by Trametes pubescens grown on sunflower-seed shells (SS) under solid-state fermentation (SFF) conditions in temporary immersion bioreactors was studied. Three immersion cycles were considered: 1 min immersed and 9 min non-immersed, 1 min immersed and 30 min nonimmersed and 1 min immersed and 60 min non-immersed. The latter led to the highest laccase activities (4000-6000 U l(-1)). Also, the in vitro and in vivo decolouration of the recalcitrant textile dye Remazol Brilliant Blue R (RBBR) was assessed. It was found that RBBR (133.33 mg l(-1)) was efficiently decolourised by T. pubencens grown on SS under SSF conditions in temporary immersion bioreactors in five successive batches. The percentage of RBBR decolouration was higher than 55% in 4 h and around 70% in 24 h in all the batches. However, it was found that RBBR decolouration by the crude culture filtrates was more advantageous. Thus, an RBBR decolouration percentage of nearly 80% in 2 h was obtained. (C) 2011 Elsevier B.V. All rights reserved.

Laccase from Trametes pubescens was immobilised on alumina pellets and coated with polyelectrolytes. It was shown that this approach enhanced both laccase stability and reusability. Further, the immobilised-coated laccase was applied to the decolouration of a simulated textile effluent in laboratory-scale reactors. The Simulated textile effluent was based on the recalcitrant diazo dye Reactive Black 5 (0.5 g/L). It was found that the decolouration was due to two processes: dye adsorption on the immobilisation support and coating and dye degradation by the laccase enzyme. The adsorption process represented less than 10% of colour removal for all cases, so decolouration was mainly due to laccase action. The decolouration was performed in both batch and continuous modes. A complete decolouration of the effluent was obtained in 30-36 h for the former and 48 h for the latter without the addition of redox mediators. in addition, the decolourised effluent showed lower phytotoxicity than the original one. These encouraging results make the process suitable for its potential implementation at industrial scale. (C) 2009 Elsevier B.V. All rights reserved.

In this study crude laccases from the white-rot fungi Cerrena unicolor and Trametes hirsuta were tested for their ability to decolorize simulated textile dye baths. The dyes used were Remazol Brilliant Blue R (RBBR) (100 mg/L), Congo Red (12.5 mg/L), Lanaset Grey (75 mg/L) and Poly R-478 (50 mg/L). The effect of redox mediators on dye decolorization by laccases was also assessed. C. unicolor laccase was able to decolorize all the dyes tested. It was especially effective towards Congo Red and RBBR with 91 and 80% of color removal in 19.5 h despite the fact that simulated textile dye baths were used. Also Poly R-478 and Lanaset Grey were partially decolorized (69 and 48%, respectively). C. unicolor laccase did not need any mediators for removing the dyes. However, T. hirsuta laccase was only able to decolorize simulated Congo Red and RBBR dye baths (91 and 45%, respectively) in 19.5 h without mediators. When using mediators the decolorization capability was enhanced substantially, e.g. Poly R-478 was decolorized by 78% in 25.5 h. On the whole, both laccases showed potential to be used in industrial applications.

Because of high discharged volumes and effluent composition, wastewater from the textile industry can be considered as the most polluting amongst all industrial sectors, thus greatly requiring appropriate treatment technologies. Although some abiotic methods for the reduction of several dyes exist, these require highly expensive catalysts and reagents. Biotechnological approaches were proven to be potentially effective in the treatment of this pollution source in an eco-efficient manner. The white-rot fungi are, so far, the most efficient microorganisms in degrading synthetic dyes. This white-rot fungi's property is due to the production of extracellular lignin-modifying enzymes, which are able to degrade a wide range of xenobiotic compounds because of their low substrate specificity. In this paper, we studied the ability of the white-rot fungus Phanerochaete chrysosporium immobilised into Ca-alginate beads to decolourise different recalcitrant azo dyes such as Direct Violet 51 (DV), Reactive Black 5 (RB), Ponceau Xylidine (PX) and Bismark Brown R (BB) in successive batch cultures. To the best of our knowledge, this is the first study on the immobilisation of P. chrysosporium into Ca-alginate beads for its application in dye decolouration. P. chrysosporium was immobilised into Ca-alginate beads using a method of gel recoating to minimise cellular leaking. The immobilised fungus was transferred to 250-ml Erlenmeyer flasks containing 50 ml of growth medium and incubated on an orbital shaker at 150 rpm and 30A degrees C for 7 days. The ratio of beads/medium used was 10% (w/v). The dyes were added into the culture flasks when MnP production started (50 U l(-1)), which corresponded with the seventh cultivation day. MnP activity and dye decolouration were measured spectrophotometrically. The dyes DV, RB and PX were almost totally decolourised at the end of each batch during the course of three successive batches. However, the dye BB was more resistant to decolouration and it was not completely decolourised (86.7% in 144 h). Further, the beads were kept in sterilised calcium chloride (2 g l(-1)) for 3 weeks at 4A degrees C. After these three storage weeks, the immobilised P. chrysosporium was again efficiently reused for azo dye decolouration during two successive batches, decolouration being more effective even for BB. Also, the in vitro decolouration of the aforementioned azo dyes by crude MnP from P. chrysosporium was performed. The decolouration levels obtained were lower than those attained with the whole cultures especially for RB and BB dyes, in spite of the fact that dye concentrations used were considerable lower. The good performance of the immobilisation system was likely due to the gel re-coating method utilised to prepare the alginate beads which not only maintained the beads integrity but also avoided cellular leaking. The lower decolouration percentages obtained by the enzyme indicates that the mycelial biomass may supply other intracellular or mycelial-bound enzymes, or other compounds that favour dye decolouration. Immobilised P. chrysosporium efficiently decolourised different types of azo dyes. In this decolouration process, the MnP secreted by the fungus played the main role whilst adsorption was found to be negligible except for the dye BB. Efforts should be made to scale up and apply fungal decolouration techniques to real industrial dye-containing wastewater. Further, detailed characterisation of the intermediates and metabolites produced during biodegradation must be done to ensure the safety of the decolourised wastewater.

This study deals with the biotransformation products obtained from the transformation of the anthraquinonic dye Remazol Brilliant Blue R (RBBR) by immobilised laccase from the white-rot fungus Trametes pubescens. A decolouration percentage of 44% was obtained in 42 h. RBBR transformation products were investigated using ultraviolet-visible (UV-vis) spectrum scan and High Performance Liquid Chromatography/Mass Spectrometry (LC-MS) analysis. Two compounds were identified as the transformation intermediates (m/z 304.29 and m/z 342.24) and other two as the final transformation products (m/z 343.29 and m/z 207.16). As a result a metabolic pathway for RBBR transformation by laccase was proposed. No backward polymerisation of the transformation products resulting in recurrent colouration was observed after laccase treatment of RBBR. It was also found that the biotransformation products of RBBR showed less phytotoxicity than the dye itself. (C) 2010 Elsevier Ltd. All rights reserved.