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Assessing the tolerance of immobilized laccase from a salt-tolerant strain of Trichoderma viride Pers NFCCI-2745 to heavy metal ions, detergents and copper chelating agents

Divya, L. M., Prasanth, G. K., Sadasivan, C.
International journal of environmental science and technology 2015 v.12 no.10 pp. 3225-3234
EDTA (chelating agent), Trichoderma viride, alginates, bioremediation, cations, cetyltrimethylammonium bromide, chelating agents, copper, detergents, enzyme activity, enzyme inhibition, heavy metals, immobilized enzymes, industrial effluents, industry, laccase, metal ions, polysorbates, salt tolerance, sodium azide
The biotreatment of industrial effluents that contain heavy metals, detergents and metal chelating agents represents a great concern to industries as these compounds are either toxic to microbes or they act as non-competitive inhibitors/denaturing agents for several enzymes. So, it is essential to know the effect of various agents usually present in the treatment plant on activity of the enzyme, for extending its applications in in situ treatment processes. This study describes the immobilization conditions of laccase and analysis of the sensitivity of immobilized laccase from Trichoderma viride Pers NFCCI-2745 to heavy metals, detergent and copper chelating agents. The concentrations and combinations of cations influenced the activity of immobilized enzyme and its yield. The immobilized Cu–Ba alginate enzyme showed comparatively higher activity compared to the Cu-alginate enzyme. Most of the metal ions tested enhanced laccase activity at lower concentration. Immobilized laccase retained more than 70 % of its activity even in the presence of 20 mM copper chelating agents like EDTA and sodium thioglycolic acid. Sodium azide, on the other hand, inhibited 80 % of the activity of all the beads even at a very low concentration of 0.5 mM. Cu–Ba and Cu–Ni alginate enzyme exhibited comparatively higher tolerance than Cu-alginate beads to EDTA and sodium thioglycolate. Tween 20 and cetyl trimethyl ammonium bromide significantly increased the activity of all the beads. These properties of the immobilized laccase may be aptly considered and suitably utilized in treating phenolic effluents that may contain heavy metals, detergents and certain copper chelating agents which may otherwise pose a threat to enzymatic activity.