In the control, Ca-alginate beads were able to remove about 12%
of initial RBBR dye within 90 min. While by free enzyme, this
anthraquinone dye was decolorized to 74.6% and increased up to
90.3% using immobilized laccase after 90 min of treatment (Fig. 5a).
Furthermore, the decolorization levels of RBBR did not improve by
adding 1 mM of HBT (Fig. 5a). The above results are supported by
Mechichi et al. (2006), who emphasized no effect of the redox
mediator HBT at concentrations between 0.125 and 2.5 mM on the
decolorization of RBBR. Other results also reported that the
oxidation of RBBR was easily carried out by laccase alone