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

13 p.-6 fig.-3 tab.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.Peer reviewe

The Marine-Derived Filamentous Fungi in Biotechnology

For a long time considered as essentially terrestrial organisms, filamentous fungi have recently disclosed to be widespread in marine habitats. Such a pervasiveness not only concerns obligate marine species but also a multitude of taxa known from disparate terrestrial substrates whose occurrence at sea, at first considered incidental, is now regarded as an evidence of extreme ecological flexibility. Actually, the peculiar physico-chemical properties of the marine environment are presumed to have induced special physiological adaptations that could be considered in view of a possible biotechnological exploitation of fungal strains recovered from marine sources. The potential of filamentous fungi reported from marine contexts for the manifold applications in biotechnology involving microbial strains is revised in this chapter