## 4 Enzymes Involved in Dye Degradation  
A group of lignin-containing plant-residue-decaying microorganisms has been classified in class basidiomycetes as white-rot fungi. These fungi have capability to degrade lignin molecules present in the complex polymers into carbon dioxide and water. The fungal metabolism produces several extracellular enzymes, which have been studied for their activities in the degradation of lignin and lignin-type molecules. These enzymes are reported to be heme peroxidasses, such as manganese peroxidase (MnP), versatile peroxidase (VP), lignin peroxidase (LiP), and lacase (Lac) [22; 23; 24]. Dye-decolourising peroxidase (DyP) is a member of the novel heme peroxidase family (DyP-type peroxidase superfamily), showing no homology to fungal heme peroxidases--MnP, VP, and LiP [25; 26]. Lacase and lignin peroxidase have been identified to be two main enzymes in solid-state fermentation performed with dye-adsorbed substrates [12]. Four different white-rot cultures, including _Bjerkandera adusta_, _Coriolus versicolor_, _Pleurotus ostreatus_, and _Phlebia tremlosa_ were grown in SSF to synthesise enzymes responsible for lignocellulosic and similar structure-containing materials. Three types of enzymes, lacase, lignin-peroxidase (LiP), and manganese-peroxidase (MnP), were produced in a mineral salt medium that was nitrogen-deficient. _P. tremlosa_ and _B. adusta_ produced high enzyme activities and performed better in the decolourisation of an artificial effluent consisting of five different dyes. Degradation studies were performed at a higher C:N ratio of 11.6:1 and under an N-limited condition (C:N ratio of 116:1) in a medium with 100 mg/L dye. Cultivation of _B. adusta_ for 7 days in N-rich medium decolourised dyes to 85%, and _P. tremlosa_ decolourised dyes up to 79% in 9 days. In contrast, under N-limited conditions, 86% of the effluent was decolourised by _B. adusta_ in 9 days, and 74% decolourisation was shown in the medium of _P. tremlosa_ after 11 days. Supplementation of nitrogen showed no effect on percentage dye decolourisation by _B. adusta_, though only a slight increase was noticed in _P. tremlosa_. However, the decolourisation time was reduced by nitrogen supplementation. These results indicated the potential of _P. tremlosa_ and _B. adusta_ for textile-effluent treatment [13]. Some strains of microorganisms are reported for their activity in the decolourisation of textile dyes as they are capable of producing a specific enzyme complex [26]. Such capability was explored in a different scenario in the textile industry by [PERSON] et al. [27]. The problem of faulty dyeing due to uneven colouring often occurs in the finished fabrics in the textile industry. This uneven extra colouring is usually removed through a process called chemical-stripping, which helps in removing the loose dyes from cotton fabrics. A research project was undertaken to study the stripping of colour from cotton-fabrics dyed with a synthetic dye, C.I. reactive black 5, in an environment-friendly effort using microbial-enzymes instead of using the method of stripping by synthetic chemicals. The microbial enzymes were prepared by cultivating a white-rot fungus, _Ganoderma lucidum_, in solid-state fermentation (SSF), applying optimised conditions. Crude preparations of SSF-enzyme extract were used in the biological colour-stripping process. The enzymes produced in culture extract from the fermentation of white-rot fungus _G. lucidum_, were analysed as lacase (EC1.10.3.2) with the activity of 68 U/mL, lignin peroxidase (EC1.11.1.14) with the activity 530 U/mL, and manganese peroxidase (EC1.11.1.13) with the activity of 395 U/mL. Important parameters to achieve effective colour-stripping were studied, such as enzyme activity (units) present in SSF-extracted filtrate, the conditions of enzyme reaction such as duration of enzyme contact with the coloured fabric, pH, and temperature.