Effect of Different Carbon Sources on Decolourisation of an Industrial Textile Dye Under Alkaline–Saline Conditions

White-rot fungal strains of Trametes versicolor and Phanerochaete chrysosporium were selected to study the decolourisation of the textile dye, Reactive Black 5, under alkaline–saline conditions. Free and immobilised T. versicolor cells showed 100 % decolourisation in the growth medium supplemented with 15 g l^?1 NaCl, pH 9.5 at 30 °C in liquid batch culture. Continuous culture experiments were performed in a fixed-bed reactor using free and immobilised T. versicolor cells and allowed 85–100 % dye decolourisation. The immobilisation conditions for the biomass and the additional supply of carbon sources improved the decolourisation performance during a long-term trial of 40 days. Lignin peroxidase, laccase and glyoxal oxidase activities were detected during the experiments. The laccase activity varied depending on carbon source utilized and glycerol-enhanced laccase activity compared to sucrose during extended growth.     

Enhanced decolourisation ability of laccase towards various synthetic dyes by an electrocatalysis technology

Laccase in culture filtrates of Trametes versicolor degraded a number of structurally different dyes by about 30% after 30 min though only 5% of Azure B was degraded in 1 h and Poly R-478 and fuchsin were not degraded at all even after 24 h. However, by using enzymatic electrocatalysis technology all dyes were decolourised in about 30 to 135 min.     

Decolorization of polymeric dyes by a novel Penicillium isolate

A novel polymeric dye-degrading fungal strain ATCC 74414 was isolated. Taxonomic identification including morphological and cultural characterization indicated that this isolate was a strain of Penicillium. Strain ATCC 74414 aerobically decolorized both Poly R-478 and Poly S-119 in liquid media containing 0.01% of polymeric dyes. The decolorization rate was examined in three distinct liquid media: Schenk and Hildebrandt-K₂SO₄ medium (SHK), potato dextrose broth (PDB), and half Murashige-Skoog medium (HMS). Strain ATCC 74414 rapidly decolorized R-478 in SHK medium but the color was subsequently released from the mycelial mass into the medium after 2–3 days, indicating that the decolorization in SHK medium could be due to adsorption of Poly R-478 by the mycelia. In contrast, in HMS and PDB media ATCC 74414 decolorized Poly R-478 more steadily, and the dye was initially adsorbed onto the mycelia and was subsequently decolorized without being released into the medium. Strain ATCC 74414 also decolorized Poly S-119 steadily in SHK, HMS and PDB media. It appears that the decolorization process involved initial mycelial adsorption of dye compounds, which was probably followed by biodegradation through microbial metabolism, and the decolorization may be affected by medium constituents. Although aerobic decolorization may not necessarily lead to complete mineralization of dyes, these results have suggested the potential of strain ATCC 74414 in bioremediation of dye-contaminated water and soil.     

Decolorization of Remazol Brilliant Blue (RBBR) and Poly R-478 dyes by <Emphasis Type="Italic">Bjerkandera adusta</Emphasis> CCBAS 930

An anamorphic Bjerkandera adusta CCBAS 930 strain isolated from soil was found to decolorize two anthraquinonic dyes: Remazol Brilliant Blue R and Poly R-478. The reduction in the level of phenolic compounds in liquid B. adusta cultures containing RBBR and Poly R-478 was correlated with decolorization of studied dyes, which suggested their biodegradation. It was shown that this process was coupled with induction of secondary metabolism (idiophase) and peak peroxidase activity in culture medium, and the appearance of aerial mycelium. Decolorization of dyes depended on the presence of glucose (cometabolism).     

Enhanced ligninolytic enzyme production and degrading capability of Phanerochaete chrysosporium and Trametes versicolor

Ligninolytic enzyme production by the white-rot fungi Phanerochaete chrysosporium and Trametes versicolor precultivated with different insoluble lignocellulosic materials (grape seeds, barley bran and wood shavings) was investigated. Cultures of Phanerochaete chrysosporium precultivated with grape seeds and barley bran showed maximum lignin peroxidase (LiP) and manganese-dependent peroxidase (MnP) activities (1000 and 1232 U/l, respectively). Trametes versicolor precultivated with the same lignocellulosic residues showed the maximum laccase activity (around 250 U/l). For both fungi, the ligninolytic activities were about two-fold higher than those attained in the control cultures. In vitro decolorization of the polymeric dye Poly R-478 by the extracellular liquid obtained in the above-mentioned cultures was monitored in order to determine the respective capabilities of laccase, LiP and MnP. It is noteworthy that the degrading capability of LiP when P. chrysosporium was precultivated with barley bran gave a percentage of Poly R-478 decolorization of about 80% in 100 s, whereas control cultures showed a lower percentage, around 20%, after 2 min of the decolorization reaction.     

Decolourisation of Remazol Brilliant Blue R via a novel Bjerkandera sp. strain

A novel strain of Bjerkandera sp. (B33/3), with particularly high decolourisation activities upon Poly R-478 and Remazol Brilliant Blue R (RBBR) dyes, was isolated. The role of the ligninolytic extracellular enzymes produced by this strain on decolourisation of RBBR was studied in some depth. The basis of decolourisation is an enzyme-mediated process, in which the main enzyme responsible is a recently described peroxidase with capacity for oxidation of manganese, as well as veratryl alcohol and 2,6-dimethoxyphenol in a manganese-independent reaction.     

Biodegradation of azo and phthalocyanine dyes by Trametes versicolor and Bjerkandera adusta

Eighteen fungal strains, known for their ability to degrade lignocellulosic material or lignin derivatives, were screened for their potential to decolorize commercially used reactive textile dyes. Three azo dyes, Reactive Orange 96, Reactive Violet 5 and Reactive Black 5, and two phthalocyanine dyes, Reactive Blue 15 and Reactive Blue 38, were chosen as representatives of commercially used reactive dyes. From the 18 tested fungal strains only Bjerkandera adusta, Trametes versicolor and Phanerochaete chrysosporium were able to decolorize all the dyes tested. During degradation of the nickel-phthalocyanine complex, Reactive Blue 38, by B. adusta and T. versicolor respectively, the toxicity of this dye to Vibrio fischeri was significantly reduced. In the case of Reactive Violet 5, a far-reaching detoxification was achieved by treatment with B. adusta. Reactive Blue 38 and Reactive Violet 5 were decolorized by crude exoenzyme preparations from T. versicolor and B. adusta in a H₂O₂-dependent reaction. Specific activities of the exoenzyme preparations with the dyes were determined and compared to oxidation rates by commercial horseradish peroxidase. Received: 3 February 1997 / Received revision: 9 April 1997 / Accepted: 13 April 1997     

Screening for decolorizing basidiomycetes in Mexico

A survey to isolate native white rot basidiomycetes from Northeast Mexico was conducted in the forests of the Sierra Madre Oriental in the state of Nuevo León. A total of 92 isolates from at least 20 different genera, were screened on Bran-Flakes solid plate cultures for the production of ligninolytic oxidases and/or peroxidases with guaiacol and o-anisidine as substrates; their lignin depolymerizing potential using the polymeric dye Poly R 478; their ability to decolorize anthraquinonic (Remazol Brilliant Blue Reactive), azo (Acid Red 44) and triphenylmethane (Crystal Violet) dyes. Among all fungi tested, 15 isolates showed extensive decolorization of the three dyes within a week and gave a positive reaction in guaiacol and o-anisidine tests. Nine of them were also efficient degraders of Poly R-478. Two isolates (CS5 and CU1) showed decolorization of all dyes within 5 days, comparing favorably with reference strains of P. chrysosporium, Pleurotus ostreatus, and Bjerkandera adusta. Decolorization was associated with laccase activity in both isolates and reached 90% or more for all dyes within 24 h in 8-day-old liquid cultures. The coupling of pairs 2,4-dichlorophenol + 4-aminoantipyrine and 3-dimethylaminobenzoic acid + 3-methyl-2-benzothiazolinone hydrazone, strongly suggest that the laccases of both strains correspond to those considered of high redox potential. These strains are considered good candidates for bioremediation of dye polluted effluents due to their ligninolytic potential and decolorizing performance.     

Biotransformation of Poly R-478 by continuous cultures of PVAL-encapsulated Trametes versicolor under non-sterile conditions

Mycelia of Trametes versicolor were aseptically encapsulated in PVAL hydrogel beads of 1–2?mm diameter. The encapsulated mycelia were grown continuously in an aerated reactor under non-sterile conditions. After 65 days contamination of the PVAL hydrogel beads by bacteria was found only in the outer layer to a depth of 50?μm. The encapsulated fungi still expressed ligninolytic enzymes, as confirmed by the biotransformation of Poly R-478. Elimination of Poly R-478 by encapsulated Trametes versicolor reached an efficiency of up to 89%, which was due partially to biotransformation (65%) and partially to adsorption onto biomass (24%). PVAL-encapsulated mycelia of Trametes versicolor were viable for at least 6 months without nutrient supplementation, if stored at 7?°C in a refrigerator. By encapsulation Trametes versicolor was apparently protected against microbial contaminants and against mechanical stress, which is known to inactivate ligninolytic enzymes. Encapsulated Trametes versicolor might thus be applicable for bioremediation to serve as an inoculum for reactor systems or for field-side applications.     

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.     

Evaluation of synthetic dye decolorization capacity in Ischnoderma resinosum

The little studied white rot fungus Ischnoderma resinosum was tested for its ability to decolorize seven different synthetic dyes. The strain efficiently decolorized Orange G, Amaranth, Remazol Brilliant Blue R, Cu-phthalocyanin and Poly R-478 on agar plates and in liquid culture at a relatively high concentration of 2–4 and 0.5–1 g l⁻¹, respectively. Malachite Green and Crystal Violet were decolorized to a lower extent up to the concentration of 0.1 g l⁻¹. Decolorization capacity of I. resinosum was higher than that in Phanerochaete chrysosporium, Pleurotus ostreatus or Trametes versicolor. In contrast with these thoroughly examined fungi, I. resinosum was able to degrade a wide spectrum of chemically and structurally different synthetic dyes. I. resinosum also efficiently decolorized dye mixtures. In liquid culture, Orange G and Remazol Brilliant Blue R were decolorized most rapidly; the process was not affected by different nitrogen content in the media. Shaken cultivation strongly inhibited the decolorization of Orange G.     

The physiology of anthracene biodegradation by the white-rot fungus Bjerkandera sp. strain BOS55

A recently isolated white-rot strain, Bjerkandera sp. strain BOS55, displays high extracellular peroxidase activity, and rapidly degrades polycyclic aromatic hydrocarbons (PAH). In this study, the culture conditions for the biodegradation of the model PAH compound, anthracene, were optimized with respect to O₂, N, and C. An additional objective was to determine if the decolorization of the polymeric ligninolytic indicator dye, Poly R-478, could be correlated to anthracene biodegradation observed under a wide range of culture conditions. The supply of O₂ was found to be the most important parameter in the biodegradation of anthracene. Increasing culture aeration enhanced the biodegradation of anthracene and the accumulation of its peroxidase-mediated oxidation product anthraquinone. Decolorization of Poly R-478 was less affected by inadequate aeration. Provided that ample aeration was supplied, the degradation of anthracene under different culture conditions was strongly correlated with the ligninolytic activity as indicated by the rate of Poly R-478 decolorization. Concentrations up to 22 mM NH₄ ⁺ N did not repress anthracene biodegradation and only caused a 0%–40% repression of the Poly R-478 decolorizing activity in various experiments. A cosubstrate requirement of 100 mg glucose / mg anthracene biodegraded was observed in this study.     

Decolourisation of Remazol Brilliant Blue R via a novel Bjerkandera sp. strain

A novel strain of Bjerkandera sp. (B33/3), with particularly high decolourisation activities upon Poly R-478 and Remazol Brilliant Blue R (RBBR) dyes, was isolated. The role of the ligninolytic extracellular enzymes produced by this strain on decolourisation of RBBR was studied in some depth. The basis of decolourisation is an enzyme-mediated process, in which the main enzyme responsible is a recently described peroxidase with capacity for oxidation of manganese, as well as veratryl alcohol and 2,6-dimethoxyphenol in a manganese-independent reaction.     

Biodecolourisation of some industrial dyes by white-rot fungi

Eight white-rot fungal strains were screened for biodecolourisation of eight dyes commercially employed in various industries. Decolourisation of Poly R 478 was used as a standard to ascertain the dye-decolourisation potential of various fungi. All the fungi tested significantly decolourised Poly R 478 on solid agar medium. When tested in a nitrogen-limited broth medium, Dichomitus squalens, Irpex flavus, Phlebia spp. and Polyporus sanguineus were better industrial dye decolourisers than Phanerochaete chrysosporium.     

Decolourisation of model and industrial dyes by mitosporic fungi in different culture conditions

Six mitosporic fungi belonging to five species (Aspergillus flavus var. flavus, Aspergillus ochraceus, Cladosporium cladosporioides, Penicillium glabrum and Penicillium verrucosum) were selected from a screening on 258 fungal strains as the most promising for their ability to remove 2 model dyes in solid conditions. Hence they were tested in liquid conditions for their ability to decolourise 3 model dyes and 9 industrial dyes widely used in the textile industry. The influence of the culture medium, particularly its carbon:nitrogen ratio, on biomass development and decolourisation capacity was considered. All the strains were able to grow in the dyed media and displayed various degrees of decolourisation according to the dye and culture medium. The decolourisation was due to biosorption phenomena. Aspergillus ochraceus performed the highest decolourisation yield being able to remove all dyes over 90%. This strain was also found very effective, both in the living and inactivated form, against simulated effluents that mimicked the recalcitrance of real wastewaters being composed of ten different dyes at high concentration (1,000 ppm), in saline solution.     

An Evaluation of Soil Colonisation Potential of Selected Fungi and their Production of Ligninolytic Enzymes for Use in Soil Bioremediation Applications

Initially sixteen fungi were screened for potential ligninolytic activity using decolourisation of a polymeric dye Poly R-478. From this, four fungi were selected, Trametes versicolor, Pleurotus ostreatus, Collybia sp., and an isolate (identified as Rhizoctonia solani) isolated from a grassland soil. Differences in the ligninolytic enzyme profiles of each of the fungi were observed. All of the four fungi tested produced MnP and laccase while the Collybia sp. and R. solani produced LiP in addition. Enzyme activity levels also varied greatly over the 21 days of testing with T. versicolor producing levels of MnP and laccase three to four times greater than the other fungi. The four fungi were then tested for their ability to colonise sand, peat (forest) and basalt and marl mixed till (field) soils through visual measurement and biomass detection in soil microcosms. Trametes versicolor and the Collybia sp. failed to grow in any of the non-sterilised soils whereas the R. solani and P. ostreatus isolates grew satisfactorily. Primers were␣designed to detect MnP and laccase genes in P.␣ostreatus and RTPCR was used to detect that these genes are expressed in forest and field soils.     

Treatment and kinetic modelling of a simulated dye house effluent by enzymatic catalysis

Biocatalytic treatment of a synthetic dye house effluent, simulating a textile wastewater containing various reactive dyestuffs (Reactive Yellow 15, Reactive Red 239 and Reactive Black 5) and auxiliary chemicals, was investigated in a batch reactor using a commercial laccase. A high decolourisation (above 86%) was achieved at the maximum wavelength of Reactive Black 5. The decolourisation at the other dyes wavelengths (above 63% for RY15 and around 41% for RR239) and the total decolourisation based on all the visible spectrum (around 55%) were not so good, being somewhat lower than in the case of a mixture of the dyes (above 89% for RB5, 77% for RY15, 68% for RR239 and above 84% for total decolourisation). Even so, these results suggest the applicability of this method to treat textile dyeing wastewaters. Kinetic models were developed to simulate the synthetic effluent decolourisation by commercial laccase. The kinetic constants of the models were estimated by minimizing the difference between the predicted and the experimental time courses. The close correlation between the experimental data and the simulated values seems to demonstrate that the models are able to describe with remarkable accuracy the simulated effluent degradation. Water quality parameters such as TOC, COD, BOD₅ and toxicity were found to be under the maximum permissible discharge limits for textile industries wastewaters.     

Evaluation of the white-rot fungi Ganoderma australe and Ceriporiopsis subvermispora in biotechnological applications

Ganoderma australe is a white-rot fungus that causes a selective wood biodelignification in some hardwoods found in the Chilean rainforest. Ceriporiopsis subvermispora is also a lignin-degrading fungus used in several biopulping studies. The enzymatic system responsible for lignin degradation in wood can also be used to degrade recalcitrant organic pollutants in liquid effluents. In this work, two strains of G. australe and one strain of C. subvermipora were comparatively evaluated in the biodegradation of ABTS and the dye Poly R-478 in liquid medium, and in the pretreatment of Eucalyptus globulus wood chips for further kraft biopulping. Laccase was detected in liquid and wood cultures with G. australe. Ceriporiopsis subvermispora produce laccase and manganese peroxidase when grown in liquid medium and only manganese peroxidase was detected during wood decay. ABTS was totally depleted by all strains after 8 days of incubation while Poly R-478 was degraded up to 40% with G. australe strains and up to 62% by C. subvermispora after 22 days of incubation. Eucalyptus globulus wood chips decayed for 15 days presented 1–6% of lignin loss and less than 2% of glucan loss. Kraft pulps with kappa number 15 were produced from biotreated wood chips with 2% less active alkali, with up to 3% increase in pulp yield and up to 20% less hexenuronic acids than pulps from undecayed control. Results showed that G. australe strains evaluated were not as efficient as C. subvermispora for dye and wood biodegradation, but could be used as a feasible alternative in biotechnological processes such as bioremediation and biopulping.     

Accelerated decolorization of reactive azo dyes under saline conditions by bacteria isolated from Arabian seawater sediment

Presence of huge amount of salts in the wastewater of textile dyeing industry is one of the major limiting factors in the development of an effective biotreatment system for the removal of azo dyes from textile effluents. Bacterial spp. capable of thriving under high salt conditions could be employed for the treatment of saline dye-contaminated textile wastewaters. The present study was aimed at isolating the most efficient bacterial strains capable of decolorizing azo dyes under high saline conditions. Fifty-eight bacterial strains were isolated from seawater, seawater sediment, and saline soil, using mineral salt medium enriched with 100?mg?l^?1 Reactive Black-5 azo dye and 50?g NaCl l^?1 salt concentration. Bacterial strains KS23 (Psychrobacter alimentarius) and KS26 (Staphylococcus equorum) isolated from seawater sediment were able to decolorize three reactive dyes including Reactive Black 5, Reactive Golden Ovifix, and Reactive Blue BRS very efficiently in liquid medium over a wide range of salt concentration (0–100?g NaCl l^?1). Time required for complete decolorization of 100?mg dye l^?1 varied with the type of dye and salt concentration. In general, there was an inverse linear relationship between the velocity of the decolorization reaction (V) and salt concentration. This study suggested that bacteria isolated from saline conditions such as seawater sediment could be used in designing a bioreactor for the treatment of textile effluent containing high concentration of salts.     

Synthetic dye decolorization capacity of white rot fungus Dichomitus squalens

The ability to decolorize eight chemically different synthetic dyes (Orange G, Amaranth, Orange I, Remazol Brilliant Blue R (RBBR), Cu-phthalocyanin, Poly R-478, Malachite Green and Crystal Violet) by the white rot fungus Dichomitus squalens was evaluated on agar plates. The fungus showed high decolorization capacity and was able to decolorize all dyes tested, but not to the same extent. Some of the dyes did not limit the decolorization capacity of the strain tested even at a concentration of 2g/l. The presence of the dyes in solid media reduced the mycelial growth rate of D. squalens; a positive correlation was found between the growth rate and the decolorization ability. Decolorization of Orange G and RBBR was studied also in liquid culture, where both dyes caused an enhancement of ligninolytic enzyme and overall hydrogen peroxide production and a decrease of biomass production. RBBR was removed to a higher extent than Orange G.