Decolorization potential of some reactive dyes with crude laccase and laccase-mediated system.

In this study, decolorization of dyestuffs, such as Reactive Red 198, Rem Blue RR, Dylon Navy 17, Rem Red RR, and Rem Yellow RR was studied using laccase and laccase-mediated system. The laccases are known to have an important potential for remediation of pollutants. Among these dyestuffs, decolorization of Rem Blue RR and Dylon Navy 17 was performed with crude laccase under optimized conditions. Vanillin was selected as laccase mediator after screening six different compounds with Rem Yellow RR, Reactive Red 198, and Rem Red RR as substrates. However, Rem Yellow RR was not decolorized by either laccase or laccase-mediated system. It is observed that the culture supernatant contained high laccase activity after treatment with catalase that was responsible for the decolorization. Besides, culture supernatant with high laccase activity as enzyme source was treated with catalase; in this way, the hypothesis that laccase was the enzyme responsible for decolorization was supported. The Rem Blue RR was decolorized with 64.84% under the optimum conditions and Dylon Navy 17 with 75.43% with crude laccase. However, using the laccase and vanillin, the decolorization of Reactive Red 198 and Rem Red RR was found to be 62% and 68%, respectively. Our study demonstrated that the decolorization abilities of laccase and/or laccase mediator systems were based on the types of mediator, the dye structure, and the standard experimental conditions. Also, the electrochemical behaviors of some samples were studied. The redox potentials of these samples were determined using cyclic voltammetry on glassy carbon electrode in phosphate buffer (pH 6) solution.

Enhancement with inducers of lacasse production by some strains and application of enzyme to dechlorination of 2, 4, 5-trichlorophenol

Lacasse is one of the extracellular enzymes excreted from white and brown rot fungi, which is involved in ligninolysis. In the present study, the effects of the addition of lacasse inducers to the medium on enhancement of enzyme production under conditions of submerged fermentation were researched. At first, a culture medium was selected suitable for lacasse production. To increase the production of lacasse using different inducers and to examine the ability of dechlorination, this article focuses on screen lacasse activity of 21 basidiomycetes isolates grown in five culture media. All inducers evaluated influenced lacasse activity positively except for gallic acid, mannitol, and malt extract for studied isolates. Our findings showed that lacasse activity of Trametes versicolor ATCC (200801) when it was induced with wheat bran reached up to 29.08 U ml-1 and was examined the ability of dechlorination of 2, 4, 5-trichlorophenol (2,4,5-TCP). The parameters including pH, initial substrate concentration, amount of enzyme, period of reaction, and temperature were tested for dechlorination process. Correlation between oxygen consumption and dechlorination processes under the determined optimum conditions was analyzed. Toxicity of 2, 4, 5-TCP before and after enzymatic treatment was evaluated by Microtox test. The results demonstrated that toxicity of intermediates formed 2, 4, 5-TCP did not change.

New fungal biomasses for cyanide biodegradation.

Cyanide, a hazardous substance, is released into the environment as a result of natural processes of various industrial activities which is a toxic pollutant according to Environmental Protection Agency. In nature, some microorganisms are responsible for the degradation of cyanide, but there is only limited information about the degradation characteristics of Basidiomycetes for cyanide. The aim of the present study is to determine cyanide degradation characteristics in some Basidiomycetes strains including Polyporus arcularius (T 438), Schizophyllum commune (T 701), Clavariadelphus truncatus (T 192), Pleurotus eryngii (M 102), Ganoderma applanatum (M 105), Trametes versicolor (D 22), Cerrena unicolor (D 30), Schizophyllum commune (D 35) and Ganoderma lucidum (D 33). The cyanide degradation activities of P. arcularius S. commune and G. lucidum were found to be more than that of the other fungi examined. The parameters including incubation time, amount of biomass, initial cyanide concentration, temperature, pH and agitation rate were optimized for the selected three potential fungal strains. The maximum cyanide degradation was obtained after 48 h of incubation at 30°C by P. arcularius (T 438). The optimum pH and agitation rate were measured as 10.5 and 150 rev/min, respectively. The amount of biomass was found as 3.0 g for the maximum cyanide biodegradation with an initial cyanide concentration of 100mg/L. In this study, agar was chosen entrapment agent for the immobilization of effective biomass. We suggested that P. arcularius (T 438) could be effective in the treatment of contaminated sites with cyanide due to capability of degrading cyanide.

Biodegradation of cyanide by a white rot fungus, Trametes versicolor.

The cyanide degradation abilities of three white rot fungi, Trametes versicolor ATCC 200801, Phanerochaete chrysosporium ME 496 and Pleurotus sajor-caju, were examined. T. versicolor was the most effective with 0.35 g dry cell/100 ml degrading 2 mM KCN (130 mg/l) over 42 h, at 30 degrees C, pH 10.5 with stirring at 150 rpm.