Involvement of lignin peroxidase in the decolourization of black olive mill wastewaters by Geotrichum candidum

AIM: Decolourization of black olive mill wastewaters (OMW) by depolymerization of phenolic compounds by Geotrichum candidum. METHODS AND RESULTS: Our results show that G. candidum is able to grow on black OMW supplemented with carbon source and nitrogen. The Geotrichum growth decreased the pH and induced a 49% of colour removal when the black OMW was supplemented with glycerol and diammonium tartrate (20 mm ammonium). An improvement of 10% of colour removal was observed when the culture was supplemented with veratryl alcohol. The decolourization was inhibited with glutamate as nitrogen source. CONCLUSION: Our results suggest the potential use of G. candidum in black OMW decolourization and support the concept that lignin peroxidase (LiP) of G. candidum is involved in the depolymerization of phenolic compounds. Significance and Impact of the Study: This is the first report of LiP production by G. candidum on OMW.     

Decolourization of paprika dye effluent with hydrogen peroxide produced by glucose oxidase

Abstract

Hydrogen peroxide was produced from bran by a two-step process using cellulase/xylanase and glucose oxidase, sequentially. The decolourization efficiency of the produced reagent was tested using paprika oil dye (effluent from industrial source) and high levels of colour removal (96%) were achieved after saponification pre-treatment and hydrogen peroxide application. The method is economically and environmentally advantageous since lower energy and chemical input are needed and wastewater pollution is considerably reduced. At the same time, the utilization of waste materials was successfully achieved.     

Production and synthetic dyes decolourization capacity of a recombinant laccase from Pichia pastoris

Aims:  To produce and purify a recombinant laccase from Pichia pastoris and to test its ability in decolourization of synthetic dyes.
Methods and Results:  A cDNA encoding for a laccase was isolated from Pycnoporus sanguineus and was expressed in P. pastoris strain SMD1168H under the control of the alcohol oxidase (AOX1) promoter. The laccase native signal peptide efficiently directed the secretion of the recombinant laccase in an active form. Factors influencing laccase expression, such as cultivation temperature, pH, copper concentration and methanol concentration, were investigated. The recombinant enzyme was purified to electrophoretic homogeneity, and was estimated to have a molecular mass of about 62·8 kDa. The purified enzyme showed a similar behaviour to the native laccase produced by P. sanguineus . Four different synthetic dyes including azo, anthraquinone, triphenylmethane and indigo dyes could be efficiently decolourized by the purified recombinant laccase without the addition of redox mediators.
Conclusions:  Heterologous production of P. sanguineus laccase in P. pastoris was successfully achieved. The purified recombinant laccase could efficiently decolourize synthetic dyes in the absence of mediators.
Significance and Impact of the Study:  This study is the first report on the synthetic dye decolourization by the recombinant P. sanguineus laccase. The decolourization capacity of this recombinant enzyme suggested that it could be a useful biocatalyst for the treatment of dye-containing effluents.     

Biological treatment of textile dye acid violet-17 by bacterial consortium in an up-flow immobilized cell bioreactor

AIMS: To develop a cost effective and efficient biological treatment process for small scale textile processing industries (TPI) releasing untreated effluents containing intense coloured Acid violet-17 (AV-17), a triphenyl methane (TPM) group textile dye. METHODS AND RESULTS: The samples collected from effluent disposal sites of TPI were used for selective enrichment of microbial populations capable of degrading/decolourizing AV-17. A consortium of five bacterial isolates was used to develop an up-flow immobilized cell bioreactor for treatment of feed containing AV-17. The bioreactor, operating at a flow rate of 6 ml x h(-1), resulted in 91% decolourization of 30 mg AV-17/l with 94.3 and 95.7% removal of biochemical oxygen demand and chemical oxygen demand of the feed. Comparison of the input and output of the bioreactor by UV-visible, thin layer chromatography and (1)H-nuclear magnetic resonance spectroscopy indicates conversion of the parent dye into unrelated metabolic intermediates. SIGNIFICANCE: These results will form a basis for developing 'on-site' treatment system for TPI effluents to achieve decolourization and degradation of residual dyes.     

Screening of fungal isolates and properties of Ganoderma applanatum intended for olive mill wastewater decolourization and dephenolization

AIMS: To investigate different autochthonous isolates of wood-rotting fungi for the removal of both colour and phenolic compounds from olive mill wastewaters (OMW). METHODS AND RESULTS: The isolates Bjerkandera adusta Ba-100, Fomes fomentarius Ff-106, Ganoderma applanatum Ga-20, Irpex lacteus Il-3, Trametes versicolor Tv-101 and Tv-103 were preliminarily screened for their OMW-decolourizing potential on potato dextrose agar supplemented with different OMW concentrations. A further screening of batch cultures under different agitation speeds, to test the effect of shear stress, resulted in the selection of isolate G. applanatum Ga-20. Batch cultures grown in OMW-based medium exhibited strong laccase induction and significant decrease in the values of phenols, colour and chemical oxygen demand. Concomitant onset of laccase activity and colour removal was observed, and apart from laccase, neither lignin peroxidase nor manganese-dependent peroxidase activities were detected. Moreover, the depletion of aromatic compounds with high and low apparent molecular mass was observed by chromatographic analysis. CONCLUSIONS: Isolate G. applanatum Ga-20 exhibited interesting properties for its use in bioremediation of OMW, namely high removal of recalcitrant phenolic compounds and strong colour abatement. SIGNIFICANCE AND IMPACT OF THE STUDY: For the first time, the white-rot fungus G. applanatum proves to be effective for the decolourization and dephenolization of OMW.     

De-colourization of textile effluent using immobilized Geotrichum candidum: an insight into mycoremediation

Textile effluent is generally complicated to manage because of its extremely noxious and recalcitrant coloured compositions. Mycoremediation is an extensively used strategy for the competent degradation of hazardous pollutants present in textile effluent. Fungus could be immobilized in synthetic or natural matrices. The current study shows the decolourization of the textile effluent by 85·5 and 98·5% within 6 h using suspended and immobilized fungus, Geotrichum candidum with optimized parameters like inoculum size (5%), pH (4·5), and temperature (30°C). To maintain a high biomass of fungal population and enhance the retention of fungal strain in the contaminated sites, the fungi need to be immobilized. Hence, the fungus was immobilized naturally onto the selected inert support that is, coconut fibres by the means of adsorption, where they grew as active films on the fibres after being grown in the culture broth. The optimized process parameters of inoculum size, fibre quantity and agitation speed for immobilized G. candidum were 5%, 2·2 g l⁻¹ of effluent and 100 rev min⁻¹ respectively. High level of laccase (22 and 25 U l⁻¹ in suspended and immobilized fungal cells treatment respectively) was observed during the process of decolourization and it was found that decolourization was directly proportional to the laccase activity. The UV–vis, FTIR, ¹H NMR and GC-MS analyses of treated textile industrial wastewater revealed the degradation of toxic pollutants in the textile effluent and formation of lower molecular weight intermediates. The study revealed a higher efficacy of immobilized G. candidum in comparison to suspended fungal culture, employing ligninolytic enzyme laccase, which catalyzes the degradation/transformation of aromatic dyes in the textile effluent thus decolourizing it.     

The effect of phenolic acids and molasses spent wash concentration on distillery wastewater remediation by fungi

The effect of gallic acid, vanillic acid, and molasses spent wash (MSW) concentration on growth and decolourizing capability of four fungi (Geotrichum candidum, Coriolus versicolor, Phanerochaete chrysosporium and Mycelia sterilia) was studied. Fungal growth was inhibited to a varying extent in the presence of gallic and vanillic acid, except for G. candidum, which was unaffected by gallic acid. G. candidum and P. chrysosporium growth rates increased in the presence of increasing concentrations of MSW (up to 50% v/v), however, growth of M. sterilia and C. versicolor was inhibited at spent wash concentrations above 5% (v/v). Increasing the concentration of MSW from 6·25% (v/v) to 12·5% (v/v) increased the decolourizing ability of each fungus, except for M. sterilia. C. versicolor exhibited greatest colour removal with a reduction of 0·43 units at A₄₇₅ (equivalent to 53% colour reduction) after 10 days growth in 12·5% (v/v) MSW.     

Decolourization of Municipal Effluent and Sludge by Pleurotus sajor-caju and Pleurotus ostreatus

Summary The Americana Municipal Treatment Station, S?o Paulo, Brazil, manages 400 l of effluent s⁻¹, from domestic and textile origin, which produces an average of 20 t of sludge per day. The decolourization of the effluent and sludge by three strains of Pleurotus (Pleurotus sajor-caju F2, F6 and Pleurotus ostreatus) was evaluated. The strains of P. sajor-caju F2 and F6 were able to decolourize the sludge, while P. ostreatus was less efficient. Detoxification was appraised with three bioassays comprising the cnidarian Hydra attenuata, the alga Selenastrum capricornutum and lettuce seeds. After exposure to fungi, effluent toxicity decreased but not that of its sludge. Strain P. sajor-caju F6 presented signs of toxicity shown by electron microscopy in the presence of the effluent. The three strains produced high amounts of manganese-peroxidase (Mn–P) and laccase in the presence of the sludge. Although P. ostreatus produced large amount of Mn–P and laccase enzymes, these enzymes did not result in decolourization of the sludge, suggesting that other factors are likely to be involved. Carbon content decreased only in the treatment with P. ostreatus.