Main content area

A halotolerant laccase from Chaetomium strain isolated from desert soil and its ability for dye decolourization

Mtibaà, Rim, de Eugenio, Laura, Ghariani, Bouthaina, Louati, Ibtihel, Belbahri, Lasaad, Nasri, Moncef, Mechichi, Tahar
3 Biotech 2017 v.7 no.5 pp. 329
Chaetomium, anion exchange chromatography, arid soils, bioremediation, calcium, decolorization, desert soils, dyes, enzyme activity, fungi, industrial applications, iron, isoelectric point, laccase, magnesium, mercury, metal ions, molecular weight, pH, polyacrylamide gel electrophoresis, salt tolerance, silver, sodium chloride, temperature, ultrafiltration, zinc
A novel fungal laccase produced by the ascomycete Chaetomium sp. isolated from arid soil was purified and characterized and its ability to remove dyes was determined. Extracellular laccase was purified 15-fold from the crude culture to homogeneity with an overall yield of 50% using ultrafiltration and anion-exchange chromatography. The purified enzyme was found to be a monomeric protein with a molecular mass of 68 kDa, estimated by SDS-PAGE, and with an isoelectric point of 5.5. The optimal temperature and pH value for laccase activity toward 2,6-DMP were 60 °C and 3.0, respectively. It was stable at temperatures below 50 °C and at alkaline conditions. Kinetic study showed that this laccase showed higher affinity on ABTS than on 2,6-DMP. Its activity was enhanced by the presence of several metal ions such as Mg²⁺, Ca²⁺ and Zn²⁺, while it was strongly inhibited by Fe²⁺, Ag⁺ and Hg²⁺. The novel laccase also showed high, remarkable sodium chloride tolerance. Its ability to decolorize different dyes, with or without HBT (1-hydroxy-benzotriazole), as redox mediator, suggests that this protein may be useful for different industrial applications and/or bioremediation processes.