Screening of Trametes strains for efficient decolorization of malachite green at high temperatures and ionic concentrations

Abstract

Trametes (synonym Coriolous) species are the most important sources for laccases with attractive properties. Several Trametes species were screened for their ability to produce laccase and decolorize malachite green (MG). Trametes trogii Berk S0301 was chosen for further study because it showed the highest 2,2′-azino bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) oxidization ability, which is closely correlated with MG decolorization. The laccase activity of T. trogii Berk S0301 was enhanced up to 34.3-fold and 5.6-fold by Cu2+ (1.5 mM) and Tween 80 (7 g L−1), respectively. Mn2+, Mg2+, Zn2+, Co2+ and Na+ (100 mM) only slightly (less than 10% inhibition) affected MG decolorization by the crude laccase of T. trogii Berk S0301. MG was decolorized effectively at pH 4.5–7.0 and 30–80 °C with an optimum decolorization at pH 6 and 50–70 °C. Phyto- and micro-toxicity tests revealed that less toxic metabolites were formed after laccase treatment. The present work demonstrates that strain T. trogii Berk S0301 and its laccase may facilitate novel and more efficient bio-catalytic process applications.