Production of laccase enzyme for their potential application to decolorize fungal pigments on aging paper and parchment

摘要

Laccases are enzymes belonging to the group of oxidases. Laccases catalyze the oxidation of a variety of phenolic compounds, diamines and aromatic amines. Twenty-four fungal isolates were isolated from biodeteriorated ancient paper and parchment. These isolates were identified and found to belong to six genera: Alternaria, Aspergillus, Cladosporium, Penicillium, Rhizopus and Trichoderma, and were tested for producing laccase enzyme. Trichoderma harzianum have the ability of secreted laccase enzyme. The maximum production of laccase enzyme by T. harzianum was observed at 35 °C and pH 5 after 6 days. The highest activity of laccase achieved at 35 °C and pH 5 during the reaction. FT1R analysis revealed that the structure of extracted fungal pigmentshas aromatic ring and phenols group. Crude laccase was capable to decolorize different pigment structures. The enzyme showed great decolorization efficiency toward the extracted yellow pigment produced from Asp. terrus and Asp. ochareceous treated by 200|il of partially purified enzyme. Laccase enzyme was used to decolorization pigment secreted from deteriorated pigmented fungi on paper and parchment during 30 days by using a pieces of paper and parchment inoculated by spore suspension. The results indicated that a high removal effect of fungal pigment on paper (71.21%) was recorded comparing to parchment samples (32.39%).