Decolorization of textile dyes using recombinant laccase PSLCC2 from Pycnoporus sanguineus

Enzymes as biological catalysts are widely used in many industries ranging from processes in the food and beverage industries, the textile industry, the detergent and chemical industries, the leather industry, the cosmetic and medical industries.The discovery of recombinant DNA technology and the advancement of genetic engineering have opened the way for the production of enzymes on an industrial scale and it has become possible to produce enzymes on a very large scale. Laccases(EC 1.10.3.2) are multioxidoreductases belonging to the multicopper containing oxidasess. The presence of various types of laccase-producing species has led to the existence of laccases with the different functions and the widespread substrate diversity. Also due to this reason their optimum temperature and pH conditions are quite variable. The use of the laccases with mediators that increase their substrate diversity and activity is another aspect that increase the potential use of laccases in various industrial and biotechnological applications. Preferably, laccases are promisingly used for bioremediation of the pollutants which are harmful and toxic to some environment In this study a laccase gene Pslcc2 isolated from the white-rot fungus Pycnoporus sanguineus MUCL 38531 has been expressed in the Pichia pastoris which is a yeast strain that is very suitable for heterologues protein productions. The decolorization potential of the resultant recombinant laccase was then investigated for synthetic textile dyes. Seven chemically different dyes classified as Azo and triarylmethane dyes were tested in the decolorization studies. Its decolorization efficiencies were analysed in the presence of three different mediators.. ABTS (2,2'-azine-bis 3-ethylbenzothiazoline-6-sulfonic acid) was used as a synthetic mediator and syringaldehyde and p-coumaric acid were used as natural mediators. Mutagenicity of these dyes before and after laccase treatment were also investigated by employing Ames test. As results, it was found that mediators significantly increase the decolorization efficiency of recombinant laccase PsLcc2.Furthermore, in addition to the decolorization of these textile dyes, no mutagenicity was observed after the recombinant PsLcc2 laccase treatment. Briefly, the recombinant laccase PsLcc2 is a promising candidate for decolorization and detoxification of Azo and Triarylmethane dyes.