Biodegradation of textile azo-dyes byPhanerochaete chrysosporium

Of 18 commercially used textile dyes, eight were degraded by the white rot fungus,Phanerochaete chrysosporium, by 40 to 73% based on decrease of colour. Both the lignin-degrading enzyme system ofP. chrysosporium and adsorption to its cell mass were involved in the degradation of the diazo dye, Reactofix Gold Yellow. Degradation was best achieved by adding the dye to the medium and then inoculating with pre-grown mycelium; inoculation with spores resulted mainly in dye adsorption.     

Decolorizing Reactive Textile Dyes with White‐Rot Fungi by Temporary Immersion Cultivation

The decontamination of effluents from textile industries is problematic due to the fact that textile dyes are resistant to degradation in the environment. Enzymes from white rot fungi, especially laccase, are able to degrade various complex aromatic structures, and are therefore able to decolorize textile dyes. The white‐rot fungi Trametes versicolor and Phanerochaete chrysosporium were immobilized, separately, on both pine wood chips and palm oil fiber, and cultivated in the temporary immersion RITA® (Récipient à Immersion Temporaire Automatique) System, which was adapted to serve as a fungal bioreactor in a series of four experiments to determine optimal conditions for decolorizing the textile dyes Levafix Blue and Remazol Brilliant Red. The maximum rate of decolorization of both dyes occurred within 24 h of incubation, and laccase was detected in the system.     

White‐rot fungi combined with lignite granules and lignitic xylite to decolorize textile industry wastewater

The feasibility of using immobilized fungi to decolorize textile industry wastewater containing dyes was examined in experiments with: two species of white‐rot fungi (a Marasmius species from Indonesia, which produces copious biomass, and Trametes hirsuta, which produces high levels of laccase); two types of lignite products as adsorbents and solid substrates (lignitic xylite and lignite granules); and four simulated wastewaters, each containing a different kinds of reactive textile azo dye. The growth, extracellular enzyme production, dye degradation and dye absorption parameters afforded by each permutation of fungus, substrate and dye were then measured. Both fungal species grew poorly on xylite, but much better on lignite granules. Marasmius sp. produced up to 67 U/L laccase on lignite granules, but just 10 U/L on xylite, and no other detectable extracellular enzymes. T. hirsuta produced 1343 U/L laccase and up to 12 U/L unspecific peroxidase when immobilized on lignite granules, and 898 U/L laccase with 14 U/L unspecific peroxidase when immobilized on xylite. The amount of color lost from the dye solutions depended on both the type of dye and the enzyme levels in the fermenter.     

Potential of aquatic fungi derived from diverse freshwater environments to decolourise synthetic azo and anthraquinone dyes

A total of 37 strains of aquatic hyphomycetes and 95 fungal isolates derived from diverse freshwater environments were screened on agar plates for the decolourisation of the disazo dye Reactive Black 5 and the anthraquinone dye Reactive Blue 19. The decolourisation of 9 azo and 3 anthraquinone dyes by 9 selected aquatic fungi was subsequently assessed in a liquid test system. The fungi were representatives of mitosporic anamorphs, and 6 strains had proven ascomycete affiliations. For comparison, 5 white rot basidiomycetes were included. The majority of dyes were decolourised by several mitosporic aquatic isolates at rates essentially comparable to those observed with the most efficient white rot fungus. Under certain conditions, particular aquatic strains decolourised dyes even more efficiently than the best performing white rot basidiomycete. Upon fungal treatment of several dyes, new absorbance peaks appeared, indicating biotransformation metabolites. All together, these results point to the potential of fungi occurring in freshwater environments for the treatment of dye-containing effluents.     

Studies on desorption of individual textile dyes and a synthetic dye effluent from dye-adsorbed agricultural residues using solvents

Two solvents, A and B (A: methanol, chloroform, water in the ratio 1:1:1; B: 50% methanol), were used to extract textile dyes adsorbed onto substrates for the purpose of future analyses of the amount of dyes degraded through solid state fermentation (SSF) using white rot fungi. Barley husk, apple pommace and corncob were separately soaked in five different dye solutions and a synthetic textile effluent. A maximum value of 93% desorption of Cibacron Red from corncob was achieved using solvent A. Barley husk was the only substrate from which the synthetic textile effluent could be desorbed, with 82% being recovered using solvent A.     

Partially purified bitter gourd (Momordica charantia) peroxidase catalyzed decolorization of textile and other industrially important dyes

The aim of this study was to evaluate the enzymatic action of partially purified bitter gourd peroxidase for the degradation/decolorization of complex aromatic structures. Twenty-one dyes, with a wide spectrum of chemical groups, currently being used by the textile and other important industries have been selected for the study. Here, for the first time we have shown peroxidases from Momordica charantia (300 EU/gm of vegetable) to be highly effective in decolorizing industrially important dyes. Dye solutions, containing 50-200 mg dye/l, were used for the treatment with bitter gourd peroxidase (specific activity of 99.0 EU/mg protein). M. charantia peroxidases were able to decolorize most of the textile dyes by forming insoluble precipitate. When the textile dyes were treated with increasing concentration of enzyme, it was observed that greater fraction of the color was removed but four out of eight reactive dyes were recalcitrant to decolorization by bitter gourd peroxidase. Step-wise addition of enzyme to the decolorizing reaction mixture at the interval of 1h further enhanced the dye decolorization. The rate of decolorization was enhanced when the dyes were incubated with fixed quantity of enzyme for increasing times. Decolorization of non-textile dyes resulted in the degradation and removal of dyes from the solution without any precipitate formation. Decolorization rate was drastically increased when the textile and other industrially important non-textile dyes were treated with bitter gourd peroxidase in presence of 1.0 mM 1-hydroxybenzotriazole. Complex mixtures of dyes were prepared by taking three to four reactive textile and non-textile dyes in equal proportions. Each mixture was decolorized by more than 80% when treated with the enzyme in presence of 1.0 mM 1-hydroxybenzotriazole. Our data suggest that the peroxidase/mediator system is an effective biocatalyst for the treatment of effluents containing recalcitrant dyes from textile, dye manufacturing, dyeing and printing industries.     

Production and characterization of laccase from Cyathus bulleri and its use in decolourization of recalcitrant textile dyes

Many fungi (particularly the white rot) are well suited for treatment of a broad range of textile dye effluents due to the versatility of the lignin-degrading enzymes produced by them. We have investigated decolourization of a number of recalcitrant reactive azo and acid dyes using the culture filtrate and purified laccase from the fungus Cyathus bulleri. For this, the enzyme was purified from the culture filtrate to a high specific activity of 4,022 IU mg⁻¹ protein, produced under optimized carbon, nitrogen and C/N ratio with induction by 2,6-dimethylaniline. The protein was characterized as a monomer of 58±5.0 kDa with carbohydrate content of 16% and was found to contain all three Cu(II) centres. The three internal peptide sequences showed sequence identity (80–92%) with laccases of a number of white rot fungi. Substrate specificity indicated highest catalytic efficiency (k _cat/K _M) on guaiacol followed by 2,2′-azino-bis(3-ethylthiazoline-6-sulfonic acid) (ABTS). Decolourization of a number of reactive azo and acid dyes was seen with the culture filtrate of the fungus containing predominantly laccase. In spite of no observable effect of purified laccase on other dyes, the ability to decolourize these was achieved in the presence of the redox mediator ABTS, with 50% decolourization in 0.5–5.4 days.     

Determination of biodegradation products from sulfonated dyes by <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis>using capillary electrophoresis coupled with mass spectrometry

Microbial treatment of environmental pollutants including dyes with white rot fungi has received wide attention as a potential alternative for conventional methods in wastewater treatment. The degradation products from dyes and mechanism underlying fungal degradation of dyes is desirable to be understood. Capillary electrophoresis coupled with mass spectrometry (CE-MS) was used in this study to determine biodegradation products of 4-[(4-hydroxyphenyl)azo]-benzenesulfonic acid, sodium salt (4HABA) and Acid Orange 7 (C.I. 15510), produced by a white rot fungus, Pleurotus ostreatus. Two major degradation products, benzenesulfonic acid and 4-hydroxy-benzenesulfonic acid, from both sulfonated compounds, were identified and their kinetic profiles in biodegradation were followed by CE-MS. Another product, 1,2-naphthoquinone, from Acid Orange 7 was identified using HPLC. Formation of these products in fungal degradation is discussed.Revisions requested 8 October 2004; Revision received 12 November 2004     

Biodegradation perspectives of azo dyes by yeasts

Azo dyes are the largest class of synthetic dyes, which are widely used in the textile industry. The amount of dyestuff does not bind to the fibers and is lost in wastewater during textile processing. The discharge of colored effluents into the environment is not only aesthetically unpleasing. Moreover, dyes and their break-down products cause toxic effects and they affect photosynthetic activity of aquatic systems by reducing light penetration. A number of microorganisms belonging to different taxonomic groups of bacteria, algae, fungi and yeast have been reported for their ability to decolorize azo dyes. In the literature the ability to decolorize azo dyes by yeasts, compared to bacterial and fungal species, has been studied in a few reports. Within this review, an attempt is made to elucidate some basic biological aspects associated with the azo dye degradation by yeasts and enzymes involved that are responsible for degradation process.     

Growth, dye degradation and ligninolytic activity studies on Zimbabwean white rot fungi

White rot fungi were collected from Chirinda and Chimanimani hardwood forests in Zimbabwe and studied with respect to growth temperature optima and dye decolorization. Temperature optima were found to vary (between 25-37 degrees C) amongst the isolates. The isolates were screened for their ability to degrade the polymeric dyes; blue dextran and Poly R478 and the triphenylmethane dyes; cresol red, crystal violet and bromophenol blue. Semi-quantitative determination of the hydrolytic enzyme activities possessed by the white rot fungi was determined using the API ZYM system. Lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase activities in the fungi were also determined. No LiP was detected in any of the isolates but all isolates showed manganese peroxidase and laccase activities. Time related decolorization studies and optimum pH determinations for Poly R478 degradation by the isolates were carried out in liquid cultures. The most significant rates of Poly R478 decolorization in liquid cultures were found with the following isolates: Trametes cingulata, Trametes versicolor, Trametes pocas, DSPM95 (a species to be identified), Datronia concentrica and Pycnoporus sanguineus.     

Decolorization of Turquoise Blue HFG by Coprinus plicatilis for Water Bioremediation

Synthetic dyes are extensively used in textile dyeing, paper printing, color photography, and the pharmaceutical, food, cosmetic, and leather industries. Most synthetic dyes are toxic and highly resistant to removal due to their complex chemical structures. There is a need for investigation of the biological treatment of synthetic dyes at a low cost and in the shortest possible time; synthetic dyes are used especially in the dye and textile industries and are an important polluting agent in the wastewater dumped into the environment by these industries. White rot fungus contains a variety of extracellular enzymes, and these enzymes are used for biological degradation of organic matter. The aim of the present work is to evaluate removal of the textile dye Turquoise Blue HFG by Coprinus plicatilis. Coprinus plicatilis was able to enzymatically decolorize 100% of the dye (dye concentration 10.0 and 25.0 mg L^?1). Ultraviolet–visible (UV-vis) spectrophotometric analyses, before and after decolorization, suggest that decolorization was due to biodegradation. There was an attempt to identify metabolites with Fourier transform infrared (FT-IR) spectroscopy and gas chromatography–mass spectrometry (GC-MS) at the end of the decolorization process. These results indicate that the samples did not include any detectable metabolite. Therefore, this fungus can be used as an economical and eco-friendly tool to minimize the pollution by industries to a significant extent.     

The evaluation of pre-grown mycelial pellets in decolorization of textile dyes during repeated batch process

This study was undertaken for the possibility of application of pre-grown pellets for biotechnological treatment of dyes and textile industry waste waters. Mycelial pellets of five different white rot fungi were tested for their dye decolorization activity. The pellets of Funalia trogii, Phanerochaete chrysosporium and Trametes versicolor were determined as the most effective ones. The decolorization ability of viable pellets was compared with the decolorization (adsorption) ability of dead pellets during repeated batch studies. Astrazon Black dye was decolorized effectively, about 90%, by viable pellets of all fungi during the first use. Viable F. trogii pellets were found as the most effective pellets. Upon pellet treatment not only a high decolorization but also reduced toxicity (antimicrobial activity) of the Astrazon Black dye was recorded. This type of decolorization activity with commercial or crude laccase was partially observed. Growing cells of F. trogii in batch system showed lower efficiency in color removal of mixed dyes compared to the pre-grown pellets in repeated batch system. The results in this study showed that mycelial pellets could effectively be used as an alternative to traditional physicochemical processes.     

白腐菌对染料脱色和降解作用的研究进展

白腐菌应用于废水处理始于二十世纪八十年代。本文对印染废水的处理方法、白腐菌及其对污染物的降解机理作了简要概述 ,着重介绍了白腐菌对染料脱色和降解作用的研究进展。白腐菌对染料的脱色解降作用机理有部分尚待进一步研究 ;同时 ,白腐菌的吸附作用亦不容忽视。     

Simple and easy method for the determination of fungal growth and decolourative capacity in solid media

A technique was developed for studying the biodegradative ability of white rot fungi in different solid media. This technique enables the gravimetric determination of fungal growth (increase of biomass) and the spectrometric measurement of fungal decolourization ability (both by the determination of the production of the extracellular enzyme manganese-dependent peroxidase (MnP) and by the rate of decolourization of dyes). Bjerkandera sp., strain BOS55, was grown in different solid media. Its growth rate, decolourization of solophenil blue 2BL (azoic dye), neutral red (eurhodin dye), methyl green and crystal violet (triphenylmethane dyes) and the production of MnP were determined. Application of this technique enabled a spectrometric quantification of enzymatic activity. Assays indicate that greater amounts of MnP were present in agar plate cultures of Bjerkandera sp. than in liquid cultures.     

Effect of synthetic and natural culture media on laccase production by white rot fungi

Laccase is among the major enzymes of white rot fungi involved in lignocellulose degradation. The present paper reports its production by two white rot fungi (Coriolus versicolor, Funalia trogii) under different nutritional conditions. Various synthetic culture media and natural culture medium (molasses wastewater) were tested. Enzyme production in various synthetic culture media, molasses wastewater (vinasse) culture medium and in the absence or presence of cotton stalk supplements showed that vinasse culture medium was a better laccase-inducer medium than the synthetic culture medium. Addition of cotton stalk to various media enhanced the enzyme production. The highest laccase activity was obtained in vinasse culture medium with cotton stalk.     

Decolorization of textile indigo dye by ligninolytic fungi

The indigo dye is extensively used by textile industries and is considered a recalcitrant substance, which causes environmental concern. Chemical products used on textile processing, which affect the environment through effluents, can be voluminous, colored and varied. Vat textile dyes, like indigo, are often used and dye mainly cellulosic fibers of cotton. Decolorization of this dye in liquid medium was tested with ligninolytic basidiomycete fungi from Brazil. Decolorization started in a few hours and after 4 days the removal of dye by Phellinus gilvus culture was in 100%, by Pleurotus sajor-caju 94%, by Pycnoporus sanguineus 91% and by Phanerochaete chrysosporium 75%. No color decrease was observed in a sterile control. Thin layer chromatography of fungi culture extracts revealed only one unknown metabolite of Rf=0.60, as a result of dye degradation.     

Review paper on current technologies for decolourisation of textile wastewaters: perspectives for anaerobic biotechnology

Dyes are natural and xenobiotic compounds that make the world more beautiful through coloured substances. However, the release of coloured wastewaters represents a serious environmental problem and a public health concern. Colour removal, especially from textile wastewaters, has been a big challenge over the last decades, and up to now there is no single and economically attractive treatment that can effectively decolourise dyes. In the passed years, notable achievements were made in the use of biotechnological applications to textile wastewaters not only for colour removal but also for the complete mineralization of dyes. Different microorganisms such as aerobic and anaerobic bacteria, fungi and actinomycetes have been found to catalyse dye decolourisation. Moreover, promising results were obtained in accelerating dye decolourisation by adding mediating compounds and/or changing process conditions to high temperatures. This paper provides a critical review on the current technologies available for decolourisation of textile wastewaters and it suggests effective and economically attractive alternatives.     

食（药）用真菌比较基因组分析揭示其生态特性

食（药）用真菌可以产生多种酶系家族来降解环境中的木质纤维素,从而获得营养或与植物共生或寄生。通过注释和比较不同营养模式的食（药）用真菌中降解木质纤维素的酶类,有利于我们更好地认识食（药）用真菌的生活模式,并进一步改善培养条件。本文系统地研究了46个食（药）用真菌和3个降解木质纤维素模式真菌的基因组,根据预测蛋白质组解析了糖苷水解酶（glycoside hydrolases,GHs）、糖基转移酶（glycosyltransferases,GTs）、多糖裂解酶（polysaccharide lyases,PLs）、碳水化合物酯酶（carbohydrate esterases,CEs）、碳水化合物结合模块（carbohydrate-binding modules,CBMs）以及附属活力酶（auxiliary activities,AAs）和细胞色素P450（cytochromes P450）的种类分布。比较基因组学结果显示,食（药）用真菌中降解木质纤维素相关酶系家族的数量和种类差别很大,同时酶系家族的多样性与食（药）用真菌的生态类型也有一定的相关性。一般情况下,腐生营养真菌比共生营养真菌中降解木质纤维素酶类更多,而腐生营养中的白腐真菌和草腐真菌的酶系比褐腐真菌多。     

Differential decolorization of textile dyes in mixtures and the joint effect of laccase and cellobiose dehydrogenase activities present in extracellular extracts from Funalia trogii

The largest part of the bio-decolorization investigations have been performed to date on a single dye without exploring the behavior in complex mixtures as the real dyeing baths. Therefore, mixtures of dyes belonging to azo and anthraquinonic classes, chosen among the most utilized in textile wool dyeing, were employed for comparative enzymatic decolorization studies using the extracellular extracts from the white rot fungus Funalia trogii, to understand how the concomitant presence of more than one dye could influence their degradation course and yield.Fungal extracts containing laccase activity only were capable to partially decolorize dyes mixtures from the different classes analyzed. The deconvolution of the decolorization with time allowed to monitor the degradation of the single dyes in the mixtures evidencing a time dependent differential decolorization not observed for the singles alone. Some dyes in the blend were in fact decolorized only when the most easily converted dyes were largely transformed. These experiments would allow to help the dyeing factories in the selection of the most readily degraded dyes.Since F. trogii grown on different media and activators shows diverse levels of expression of the redox enzymes laccase and cellobiose dehydrogenase (CDH), the dyes mixtures recalcitrant to decolorization by laccase activity alone, were subjected to the combined action of extracts containing laccase and CDH. The use of CDH, in support to the activity of laccase, resulted in substantial decolorization increases (>84%) for all the refractory dyes mixtures.     

Potential of combined fungal and bacterial treatment for color removal in textile wastewater

Low efficiency of dye removal by mixed bacterial communities and high rates of dye decolorization by white-rot fungi suggest a combination of both processes to be an option of treatment of textile wastewaters containing dyes and high concentrations of organics. Bacteria were able to remove mono-azo dye but not other chemically different dyes whereas decolorization rates using Irpex lacteus mostly exceeded 90% within less than one week irrespective of dye structure. Decolorization rates for industrial textile wastewaters containing 2-3 different dyes by fungal trickling filters (FTF) attained 91%, 86%, 35% within 5-12 d. Sequential two-step application of FTF and bacterial reactors resulted in efficient decolorization in 1st step (various single dyes, 94-99% within 5 d; wastewater I, 90% within 7 d) and TOC reduction of 95-97% in the two steps. Large potential of combined use of white-rot fungi and traditional bacterial treatment systems for bioremediation of textile wastewaters was demonstrated.