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

Abstract

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 noncompetitive 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 Cualginate 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.

Laccase activity from Pleurotus ostreatus and Flammulina velutipes strains grown on agro- and forestry residues by solid-state fermentation

“…The activity of laccase secreted by fungi is affected by many factors. Additionally, it mainly includes the following categories: 1) the concentration, proportion, and type of carbon or nitrogen sources, such as glucose, peptone, and lignocellulosic biomass (Songulashvili et al 2008;An et al 2015;Han et al 2017;Palazzolo et al 2019;Thamvithayakorn et al 2019;Agrawal and Verma 2020;Atilano-Camino et al 2020;Pinheiro et al 2020); 2) various kinds or concentration of metal ions, e.g., Ca 2+ , Cu 2+ , Cd 2+ , Ag 2+ , Fe 2+ , Hg 2+ , and Mn 2+ (Wang et al 2011;Pezzella et al 2013;Divya et al 2015;Suetomi et al 2015;Zhuo et al 2017;Xu et al 2018;An et al 2020a); 3) fungal secondary metabolites, such as veratrol and ferulic acid (Galhaup et al 2002;Janusz et al 2015); 4) temperature and pH (Diaz et al 2013;Hu et al 2014); 5) fermentation method, including submerged fermentation, solid-state fermentation and unconventional method (solid-state fermentation followed by liquid fermentation) (An et al 2016b;Schalchli et al 2017;Wasak et al 2018;Gupta and Jana 2019;Wang et al 2019); 6) different species or strains (Elisashvili and Kachlishvili 2009;An et al 2016aAn et al , 2018Zhang et al 2020;Han et al 2021).…”