Abstract
A low-cost process for the production of laccases is necessary for a sustainable enzymatic wastewater treatment. Therefore, it is necessary to establish an easy and low-cost procedure for the production of laccase. In the present study the properties of crude laccase from Trametes versicolor produced by solid-substrate fermentation is investigated. The application of the enzyme for dye decolorization is also studied. Crude laccase from the studied culture established maximal activity at 45oC. The enzyme retained over 90% of its activity in the temperature range 40- 47oC and pH 4.5. The kinetic constants of the crude enzyme was also determined. In the presence of KCl, NaCl, CaCl2, MnSO4 and MgSO4, laccase demonstra- ted high stability—over 50% of its initial activity was still retained after 4-month incubation. Complete loss of enzymatic activity was observed in the presence of CuCl2, FeCl2, FeCl3 and NaN3 after 30 min of incubation. 100% decolorization by investigated crude laccase was completed in the case of Indigo Carmine for 4 h, Remazol Brilliant Blue R—for 6 h, Orange II— for 48 h and Congo Red—for 13 d.
Highlights
Laccases are extracellular, multicopper enzymes that use molecular oxygen to oxidize various aromatic and nonaromatic compounds by a radical-catalysed reaction mechanism [1]
A low-cost process for the production of laccases is necessary for a sustainable enzymatic wastewater treatment
Complete loss of enzymatic activity was observed in the presence of CuCl2, FeCl2, FeCl3 and NaN3 after 30 min of incubation. 100% decolorization by investigated crude laccase was completed in the case of Indigo Carmine for 4 h, Remazol Brilliant Blue R—for 6 h, Orange II— for 48 h and Congo Red—for 13 d
Summary
Laccases (benzenediol:oxygen oxidoreductase, EC 1.10. 3.2) are extracellular, multicopper enzymes that use molecular oxygen to oxidize various aromatic and nonaromatic compounds by a radical-catalysed reaction mechanism [1]. 3.2) are extracellular, multicopper enzymes that use molecular oxygen to oxidize various aromatic and nonaromatic compounds by a radical-catalysed reaction mechanism [1]. Laccases can be very strongly inhibited by various reagents. Small anions such as azide, halides, cyanide, thiocyanide, fluoride and hydroxide bind to the type 2 and type 3 Cu, resulting in the interruption of internal electron transfer and inhibition of activity. Other inhibitors include metal ions (e.g. Hg2+), fatty acids, sulfhydryl reagents, hydroxyglycine, kojic acid, desferal and cationic quaternary ammonium detergents the reactions with which may involve amino acid residue modifications, conformational changes or Cu chelation [2,3]. Laccases generally are more stable at alkaline pH than at acidic pH, probably due to the OH− inhibition of autooxidation
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