Increase In Laccase Production Research Articles

The effect of various inducers and their combinations with copper on laccaseproduction of Trametes versicolor pellets in a repeated-batch process

The aim of this study was to increase laccase production in Trametes versicolor ATCC 200801 pellets by using various inducers and their combinations under repeated-batch conditions. Because copper is an effective inducer for laccase production, the effect of Cu on laccase production in this strain was tested first. The optimal Cu concentration for the highest laccase production was 0.5 mM. Following this preliminary study, the effect of other inducers [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), syringaldazine, guaiacol, and 2,5-xylidine] on laccase production was determined. Copper was determined to be the most efficient inducer among the inducers used. Therefore, the synergistic effect of each inducer with Cu on laccase production in this strain was investigated. While the maximum laccase activity was 0.60 U/mL in stock basal medium (SBM) alone, the highest enzyme activities detected were 4.76 and 2.87 U/mL in SBM + 0.05 mM ABTS and SBM + 1 mM 2,5-xylidine, respectively. Maximum laccase activities obtained from the combination of the inducers were 33.61 and 26.49 U/mL in SBM + 0.5 mM Cu + 0.5 mM 2,5-xylidine and SBM + 0.5 mM Cu + 0.05 mM ABTS, respectively. These were the most efficient combinations for laccase production.

Impact of phosphate and other medium components on physiological regulation of bacterial laccase production.

Laccases are multicopper oxidases known to catalyze the transformation of a wide range of phenolic and non-phenolic substrates using oxygen as electron acceptor and forming water as the only by product. Their potential relevance in several industries requires the constant search for novel laccases. Positive outcome of the isolation of laccase producing bacteria depends on the nature and concentration of media constituents. Several attempts to isolate laccase producing bacteria failed when the phosphate-containing M9 minimal medium was used. Shift to phosphate-less M162 medium led to successful isolations. Seven bacterial isolates belonging to genera Bacillus, Lysinibacillus, Bhargavaea and Rheinheimera were used to study the effect of medium constituents on laccase production. Inorganic phosphate (≥50 mM) was found to regulate laccase synthesis negatively though no inhibitory effect of phosphate (10-500 mM) was seen on laccase activity. All isolates ceased laccase synthesis when grown in the presence of tryptone (0.2-1%), with R. tangshanensis as an exception, or yeast extract (1.5-2%) as the only C/N source in M162 medium. Supplementation upto 0.1% of glucose in basal M162 medium increased laccase production in five isolates but decreased at higher concentrations. The influence of medium components on laccase synthesis was further affirmed by zymographic studies. These observations offer possibilities of isolating promising laccase producers from diverse environmental sources. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:541-548, 2017.

English

Laccase belongs to the family of multicopper oxidase and have wide range of biotechnological applications starting from the food industry to bioremediation. However, the use of laccase at commercial scale is hindered by factors like high enzyme cost, low activity and /or stability under given conditions. This study was carried out with aim of screening for extracellular thermostable laccase producing bacteria. Twenty-two (22) laccase positive strains were isolated from the selected environmental samples while extracellular laccase activity was detected only in six strains namely TM1, TMT1, PK4, PS1, TMS1 and ASP3. The laccase enzyme produced from PK4 was found to be more thermostable with a half-life of 60 min at 80°C. The strain PK4 was identified and designated as Bacillus sp. PK4. The laccase production was optimized using one- factor-at-a-time method and maximum enzyme production were observed at the temperature of 37°C, pH 7.5, 10% inoculum size with yeast extract and glucose as the nitrogen and carbon sources, respectively at an agitation rate of 150 rpm. Copper sulphate at 0.1 mM concentration was found to maximize the laccase production among the tested inducers. Among the trace elements, FeSO4 and ZnSO4 gave the maximum laccase production for the isolated strain in comparison with the control. The effect of copper-induced time showed that the addition of copper before inoculation effectively increased the laccase production compared to the addition of copper after 2, 4, 6 and 8 h of inoculation. The optimization of the media resulted in 11.8 fold increase in laccase production. Key words: Laccase, thermostability, Bacillus sp., optimization.

Screening of eucalyptus wood endophytes for laccase activity

New lignin-degrading microorganisms and their enzymes can contribute to more efficient and environmentally sound use of lignocellulosic biomass in future biorefineries. In view of this, 127 endophytic fungi were isolated from eucalyptus trees. Strains were tested for their ability to produce ligninolytic enzymes in agar-plate medium containing ABTS, and 21 showed positive ABTS-oxidation. Positive strains in liquid medium confirmed that five produced laccase but no peroxidase activity. These strains were identified as Hormonema sp. and Pringsheimia smilacis, of the family Dothioraceae, Ulocladium sp. (Pleosporaceae) and Neofusicoccum luteum and Neofusicoccum australe (Botryosphaeriaceae). Laccase production by fungi of the family Dothioraceae is described here for the first time.To increase laccase production from these fungi, copper sulphate and ethanol were assayed as inducers. An increase in laccase activity of 85% was found for Hormonema sp. and N. luteum and 95% for N. australe. No increase was obtained for P. smilacis. A maximum temperature of 40°C is recommended for possible biotechnological applications with these four strains at pH 2 for N. luteum and N. australe, pH 4 for Hormonema sp. and pH 4–5 for P. smilacis.

Effect of Solid State Fermentation Medium Optimization on Pleurotus ostreatus Laccase Production.

The objective of this work was to increase laccase production by Pleurotus ostreatus PLAB through culture medium optimization using solid state culture conditions. Increased laccase activity was obtained through design of experiments (DOE) using the Taguchi orthogonal array (OA). Seven factors, viz. lignocellulose, glucose, yeast extract, peptone, KH(2)PO(4), MgSO(4) 7H(2)O and MnSO(4) H(2)O at three levels and pH at two levels. OA layout of L18 (2(1) x 3(7)) was selected for the proposed experimental design using Minitab 17 software. Data analysis showed that lignocellulose (20 %) and glucose (10 g L1) had positive effect, whereas KH(2)PO(4), MgSO(4)∙7H(2)O and MnSO(4)∙H(2)O did not have significant effect on laccase production. Taguchi OA analysis showed that pH 6, lignocellulose 20 %, glucose 10 g L(-1), yeast extract 6 g L(-1), peptone 15 g L(-1), KH(2)PO(4) 3 g L1, MgSO(4)∙7H(2)O 0.5 g L(-1) and MnSO(4)∙H(2)O 0.1 g L-1 were the optimal conditions to maximize laccase production. The model predicted a 30.37 U g(-1) dry wt., which agreed with the experimentally obtained laccase activity 29.15 U g(-1) dry wt. at optimal conditions.

Development of Industrial Effluent Treatment System Using White-Rot Fungi, Isolated from Nature and their Enzymes

Industrial effluents containing wastewater from textile and dyestuff industries is one of the most difficult to be treated. Since it contains various kinds of synthetic dyes with complex aromatic molecular structures, illustrating the need for a non-specific method of decolorization. Due to the low biodegradability of synthetic dyes, they can cause serious environmental pollution. Hence there's an urgent need to develop treatment system for bioremediation of dye containing industrial effluents to reduce pollution in a non-toxic manner and provide environmentally friendly treatment technology for sustainable development. In recent years white-rot fungi have attracted increasing attention as their lignolytic enzymes have the ability to degrade recalcitrant compounds and synthetic dyes. Owing to extracellular, nonspecific, free radical based lignolytic systems of WRF; they can completely eliminate a variety of xenobiotics, including synthetic dyes and industrial dyes giving rise to non-toxic compounds. Hence five white-rot fungi (isolated from nature) were evaluated for their potential to declorize two dyes Rhodamine-B and Methyl Orange in order to develop them in future as target organisms for treatment of Industrial effluents. All the fungal isolates showed high rates of decolorization, with KV10 and KV12 removing 76% color within 96 hrs. All the fungi not only decolorized the dyes but also degraded them as is evident from the shift in their absorption spectra. Linear increase in laccase production by all five fungi, was observed with a simultaneous increase in extent of decolorization, irrespective of the type of dye. The presence of the dyes in liquid medium had little or no effect on the mycelial growth, at the concentration tested.

Optimisation of Thermostable Laccase Production byThermoascus aurantiacusMTCC 375 Using Paddy Straw as Substrate and Digested Biogas Slurry (DBS) as Medium in Solid State Fermentation

Optimisation of laccase production by Thermoascus aurantiacus microbial type culture collection (MTCC) 375 using paddy straw as substrate and digested biogas slurry as medium was carried out. Laccase production by a thermophilic mould, Thermoascus aurantiacus MTCC 375, was optimised in solid state fermentation (SSF) by a conventional ‘one variable at a time approach ‘andfurther by response surface methodology. Enzyme activity was strongly affected by three independent variables namely incubation temperature, incubation period and inoculum level. The optimised conditions for maximum laccase (715.0 Ug−1 of paddy straw) production were 45°C temperature, 107 spores ml−1 and 4 days incubation period. The enzyme titre (715.0 Ug−1 of paddy straw) attained in the validation experiment of this study is higher than those reported in the literature. An overall (2.65 fold) increase in laccase production was achieved in SSF due to statistical optimisation compared to that of a conventional ‘one variable at a time approach ’. All these cultural conditions were found to have statistically significant (P < 0.05) effect on enzyme production.

Response Surface Methodology Mediated Modulation of Laccase Production by Polyporus arcularius

Screening of thirteen mushroom fungal isolates collected from Alagar Hill and Thandikudi Hill of Tamil Nadu, India, for laccase production revealed the high laccase production potential of the isolate MI 51. The mushroom isolate MI 51 was identified as Polyporus sp., based on sporophore (fruiting body) morphology and spore characteristics. Molecular identification of the fungal isolate MI 51 using primer ITS1 and ITS4 showed that isolate MI 51 shared 98 % sequence similarity with Polyporus arcularius, a basidiomycete fungus. Initial screening of production parameters using Plackett–Burman design helped in identifying the system variables/parameters which directly influenced laccase production. Laccase production by P. arcularius was optimized using central composite design (CCD) of experiments and response surface methodology (RSM) by studying influence of the growth supplements and media additives on modulating laccase production by P. arcularius. High laccase production by P. arcularius growing in basal salt medium, (9.30 IU/ml), was observed in 21 days of incubation. Results from experiments designed by CCD indicated that nearly threefold increase in laccase production (28.30 IU/ml) over the control experiments in basal salt medium could be obtained earlier at 15 days of incubation by increasing the content of the nitrogen source, yeast extract to 0.5 g/l, and by adding 250 μM CuSO4 to the basal salt medium. RSM plots showed high interaction between the variables, incubation time, yeast extract concentration, and CuSO4 concentration in the medium.

Reduced toxicity of malachite green decolorized by laccase produced from Ganoderma sp. rckk-02 under solid-state fermentation.

Statistical designs were applied for optimizing laccase production from a white-rot fungus, Ganoderma sp. rckk-02 under solid-state fermentation (SSF). Compared to unoptimized conditions [2,154 U/gds (Unit per gram of dry substrate)], the optimization process resulted in a 17.3-fold increase in laccase production (37,423 U/gds). The laccase produced was evaluated for its potential to decolorize a recalcitrant synthetic dye, malachite green. Laccase at dosage of 30 U/ml in presence of 1 mM of 1-hydroxybenzotriazole (HBT) almost completely decolorized 100 and 200 mg/l of malachite green in 16 and 20 h, respectively, at 30 °C, pH 5.5 and 150 rpm. While, higher dyes concentrations of 300, 400 and 500 mg/l were decolorized to 72, 62 and 55 % in 24, 28 and 32 h, respectively, under similar conditions. Furthermore, it was observed that the decolorized malachite green was less toxic towards the growth of five white-rot fungi tested viz. Crinipellis sp. RCK-1, Ganoderma sp. rckk-02, Coriolopsis Caperata RCK 2011, Phanerochaete chrysosporium K3 and Pycnoporous cinnabarinus PB. The present study demonstrates the potential of Ganoderma sp. rckk-02 to produce high titres of laccase under SSF, which can be exploited in conjunction with redox mediator for the decolorization of high concentrations of malachite green from water bodies.

Induction of a white laccase from the deuteromycete Myrothecium verrucaria NF-05 and its potential in decolorization of dyes

Myrothecium verrucaria NF-05 is a deuteromycete fungus capable of producing a white laccase. The optimal concentration of Cu2+ for laccase production by this strain is 0.2 mM (43.23 ± 1.16 U mL− 1). A comprehensive investigation of the induction demonstrated that NF-05 laccase production could be synergistically enhanced by various inducers, including aromatic phenols, amines and recalcitrant dyes, in the presence of 0.2 mM Cu2+. Sixteen phenols, fourteen amines and four dyes exhibited significant inductive effects on laccase production. The best inducer was 3, 3’-dimethylbenzidine, which increased laccase production to 258.1 ± 11.1 U mL− 1. These results suggest that M. verrucaria NF-05 is a promising industrial laccase producer. Based on the increased production, purified NF-05 laccase was used to decolorize dyes of various structural types in the presence of six redox mediators. Among the 26 tested dyes, the decolorization rate of six azo dyes, chromotrope 2R, orange G6, Congo red, Ponceau S, amaranth and reactive yellow 135 and two arylmethane dyes, fast green 3 and neutral red, were significantly increased by each of the six mediators. These results demonstrate the potential use of the NF-05 laccase for the decolorization of recalcitrant dyes in dye bleaching and effluent detoxification.

Enhancing laccase production by a newly-isolated strain of Pycnoporus sanguineus with high potential for dye decolouration

Response surface methodology (RSM) was applied to optimise laccase production by a new strain of Pycnoporus sanguineus, isolated from the Uruguayan forests, grown on bark shavings under semi-solid-state fermentation conditions. Enhancement of laccase production was studied, with a full 24 factorial design with two replicates and four central points. Operating under the optimal conditions obtained (pH 3.0, yeast extract 10 g L−1, glucose 5 g L−1 and bark shavings 3 g), a laccase activity of nearly 3000 U L−1 was achieved. Subsequently, the effect of different potential inducers on laccase production (Cu+2, Mn+2 and lignin) was tested using the one-factor-at-a-time approach. It was found that the addition of 0.5 mM Cu+2 into the cultures considerably increased laccase production and, thus, maximum activity values of about 16000 U L−1 were achieved. Further, the optimised culture broth (containing mainly laccase) showed high capacity to decolourise different recalcitrant synthetic dyes such as Acid Red 88 (AR88), Reactive Black 5 (RB5) and Lanaset Grey G (LG). After selecting enzyme concentration and time of reaction, almost 70% of AR88 could be decolourised in the absence of redox mediators. However, mediators were necessary to bleach RB5 and LG. Methyl syringate was the most effective mediator for AR88 (reaching a decolouration degree over 90%) and RB5 (nearly 70%). Around 80% of LG could be decolourised in the presence of violuric acid. These promising results make this enzyme a very useful tool for developing wastewater treatments.

Additive effects of CuSO4 and aromatic compounds on laccase production by Pleurotus sajor-caju PS-2001 using sucrose as a carbon source

Laccase enzymes are now commercially available, and a laccase/mediator combination is currently marketed for indigo dye bleaching in textile manufacturing; replacing traditional chemical-based processes with enzymatic technology reduces the need for effluent treatment. However, an inexpensive source of these enzymes will be needed to enable wider application of this technology. In the present work, the main objective was to increase laccase production by the mushroom Pleurotus sajor-caju strain PS-2001 grown on sucrose derived from sugar cane, one of most economical carbon sources known, by the addition of compounds that are known to affect laccase production. High laccase activities (45-62 U mL-1) were obtained with additions of syringaldazine, benzoic acid, gallic acid, and vanillin. When CuSO4 was used in conjunction with these aromatic compounds, the levels of laccase activity were further improved, reaching 58-80 U mL-1. These laccase activities indicate the potential of this strain as an enzyme producer, which has also been detected in media containing glucose, but with activity lower than that observed with sucrose.

Optimum conditions for inducing laccase production in Lentinus crinitus

Laccases are environmentally friendly alternatives in many important applications such as in bioremediation, biopulping, textile, and the food industry. They have wide substrate specificity, can oxidize a broad range of compounds, and show potential for use in various industrial processes. Therefore, developing methods to increase laccase production is important. In the current study, we aimed to identify optimum conditions for inducing laccase production in the basidiomycete Lentinus crinitus cultivated under varying nitrogen concentrations and in the presence of potential inducers of laccase production, including copper and phenolic compounds. Peak enzymatic activity (11,977 U/L) occurred at higher nitrogen concentrations (2.8 g/L nitrogen). Regardless of the nitrogen concentration, addition of copper increased the laccase activity and decreased mycelial growth, with maximum laccase activity (14,320 U/L) observed at the highest nitrogen concentration combined with 150 mM CuSO4. In addition, ethanol (0.5 or 1.0 mM) and guaiacol (1.5 mM) increased laccase production to 15,000, 14,800, and 14,850 U/L, respectively. Our findings highlighted the optimum conditions for producing L. crinitusderived laccase as potential alternatives to the conventional production and application of the enzyme.

Oxidative stress response of Beauveria bassiana to Bordeaux mixture and its influence on fungus growth and development

Chemical fungicides used to manage plant diseases may negatively affect beneficial fungi such as entomopathogens. In this study, the participation of the antioxidative system in the entomopathogenic fungus Beauveria bassiana exposed to the copper-based Bordeaux mixture fungicide and its relation with fungus growth and development were examined. The fungus was grown in submerged culture containing Bordeaux mixture at the recommended dose. Within the first 24 h of elicitation, the vegetative growth, germination, sporulation and activity of amylase and laccase and the antioxidative enzymes catalase (CAT) and superoxide dismutase (SOD), as well as the production of hydrogen peroxide (H2 O2 ), were evaluated. Bordeaux mixture inhibited B. bassiana germination (between 65 and 88%) and sporulation (between 15 and 57%) and significantly increased laccase production (≥130%), especially within the first 4 h of fungus exposure. By contrast, the mycelial growth was found to be less affected by the fungicide. These effects were accompanied with a significant increase in H2 O2 levels in fungal cells, as well as in SOD activity, but not in CAT, showing clear signs of increased oxidative stress. The effect of Bordeaux mixture on B. bassiana development was probably due to the toxicity of the copper ion itself, and it also induced an oxidative state in fungal cells.

Induction of laccases in Trametes versicolor by aqueous wood extracts

The induction of laccase isoforms in Trametes versicolor HEMIM-9 by aqueous extracts (AE) from softwood and hardwood was studied. Samples of sawdust of Pinus sp., Cedrela sp., and Quercus sp. were boiled in water to obtain AE. Different volumes of each AE were added to fungal cultures to determine the amount of AE needed for the induction experiments. Laccase activity was assayed every 24 h for 15 days. The addition of each AE (50 to 150 μl) to the fungal cultures increased laccase production compared to the control (0.42 ± 0.01 U ml(-1)). The highest laccase activities detected were 1.92 ± 0.15 U ml(-1) (pine), 1.87 ± 0.26 U ml(-1) (cedar), and 1.56 ± 0.34 U ml(-1) (oak); laccase productivities were also significantly increased. Larger volumes of any AE inhibited mycelial growth. Electrophoretic analysis revealed two laccase bands (lcc1 and lcc2) for all the treatments. However, when lcc2 was analyzed by isoelectric focusing, inducer-dependent isoform patterns composed of three (pine AE), four (oak AE), and six laccase bands (cedar AE) were observed. Thus, AE from softwood and hardwood had induction effects in T. versicolor HEMIM-9, as indicated by the increase in laccase activity and different isoform patterns. All of the enzymatic extracts were able to decolorize the dye Orange II. Dye decolorization was mainly influenced by pH. The optimum pH for decolorization was pH 5 (85%), followed by pH 7 (50%) and pH 3 (15%). No significant differences in the dye decolorizing capacity were detected between the control and the differentially induced laccase extracts (oak, pine and cedar). This could be due to the catalytic activities of isoforms with pI 5.4 and 5.8, which were detected under all induction conditions.

Laccase production by free and immobilized mycelia of Peniophora cinerea and Trametes versicolor: a comparative study

The production of laccase by immobilized mycelia of Peniophora cinerea and Trametes versicolor was studied. In an initial stage, experimental assays were performed in Erlenmeyer flasks using free and immobilized mycelium, and the performance of the fungal strains to produce the enzyme was compared. Both fungi adhered into the support material (a synthetic fiber), growing not only on the surface but also in the interspaces of the fibers. Immobilization of P. cinerea provided a 35-fold increase in laccase production when compared to the production obtained by using free mycelium. On the other hand, immobilization of T. versicolor caused a decrease in laccase activity. A comparison between the strains revealed that immobilized P. cinerea (3,500 U/L) surpassed the enzyme production by free T. versicolor (800 U/L). When the conditions that gave the best laccase production to each fungus were employed in a stirred tank bioreactor, very low laccase production was observed for both the cases, suggesting that shear stress and mycelia damage caused by the agitation impellers negatively affected the enzyme production.

Optimization of Laccase Production from &lt;i&gt;Penicillium martensii &lt;/i&gt;NRC 345

Laccase production by <i>Penicillium martensii </i>NRC 345 was optimized. Eight media with different components were screened. The enzyme formed by <i>P. martensii</i> NRC 345 was detected mainly exocellularly under shake culture condition. Laccase formation reaches its maximum value with specific activities of about 7.18 U/mg protein at the twenty-sixth day of incubation at pH 5.5 and 30°C. Galactose (5 g/l) and sodium nitrate (0.2 g/l) were found to be the best carbon and nitrogen sources for laccase formation, respectively. Replacement of galactose instead of glucose at the same concentration increased laccase production by about more than ten-fold. Among the various wastes used wheat bran induces the highest laccase production with specific activity of 39.52 U/mg protein. Tween-80 and CuSO<SUB>4</SUB>.5H<SUB>2</SUB>O, were also tested for laccase induction.

Classical breeding in Pleurotus ostreatus: a natural approach for laccase production improvement

White-rot basidiomycetes, the most common wood-rotting organisms, are characterized by their ability to produce extracellular oxidative enzymes, among which laccases are regarded as promising catalysts for many biotechnological applications. A significant obstacle to the exploitation of laccase-based bioprocesses is the large amounts of enzyme required. In this study the issue has been addressed by applying a classical breeding approach to increase laccase production yields in the white-rot fungus Pleurotus ostreatus. Starting from two different P. ostreatus varieties, three higher laccase-producing hybrids have been obtained by crossing selected compatible monokaryons. The three selected strains increased the titre of parental strains up to four fold, reaching an expression level of up to 100 000 U/L. One hybrid exhibited a more complex isoenzyme pattern, illustrating the potential of classical breeding to differentiate protein expression.

Ethanol induced response in Phanerochaete chrysosporium and its role in the decolorization of triarylmethane dye

Ethanol was added to submerged cultures of Phanerochaete chrysosporium to enhance the production of laccase and improve the decolorization of triarylmethane dye. The addition of 10 g/l ethanol resulted in a 4.7-fold increase in laccase production, while higher ethanol concentrations caused a sharp decrease in activity. The protein content increased with the increase in ethanol concentrations; on the other hand, pellet diameter and fungal biomass wet weight decreased. The addition of ethanol to the cultivation media affected both the mycelial morphology and fungal wall permeability. Although catalase assay indicated a stress response behavior, the lipid peroxidation decreased, suggesting the presence of a protective protein compound which appears in the presence of ethanol. The partial purification of the extracellular fluid (ECF) of ethanol-amended cultures resulted in a low molecular weight fraction (<5 kDa), UV–visible spectrum for this fraction showed a single sharp peak at 356 nm under ethanol stress; this peak represents glutathione, a reductive peptide which increased 2-fold after the fungus was exposed to ethanol stress. The glutathione assay, reductive activity, and the in vitro decolorization confirm that glutathione is responsible for dye reduction (65.1%) as compared to decolorization in in vivo conditions (23.8%). The use of ethanol could improve the performance of Phanerochaete chrysosporium through laccase induction for oxidation or reductive activity depending on the concentration and mode of addition of ethanol.

Decolorization of some synthetic dyes using optimized culture broth of laccase producing ascomycete Paraconiothyrium variabile

Optimization of the medium components for production of laccase by Paraconiothyrium variabile using response surface methodology was investigated. Initial screening by Plackett–Burman design was performed to select major variables out of eleven medium components, among which peptone, CuSO 4, and xylidine were found to have significant effects on laccase production. After application of the steepest ascent to approach the proximity of the optimum point, a central composite design was employed to optimize the level of the selected variables. In optimum concentrations of the most effective parameters, including peptone, 2.2 g/L, CuSO 4, 0.03 g/L, and xylidine 1.29 mM, extracellular laccase activity was enhanced from 970 U/L (in basal medium) to 16,678 U/L, which means a 17-fold increase in laccase production in the optimized medium. Supernatant of the optimized medium was used for decolorization of five synthetic dyes, among which 93% of Remazol brilliant blue R (with initial concentration of 600 mg/L) disappeared after 3 h treatment in the presence of 5 mM hydroxybenzotriazole.