Textile industries are the major source of environmental pollution in the world because they release dyes, chemical and pigments during dying process in waste water. The current study was designed with aims of screening Pleurotus ostreatus  biodegradation potential for four selected textile dyes i.e. direct pink B, direct yellow BG, dispersed red S3B and disperse yellow SRLB. The process was further optimized at two stages with Response Surface Methodology (RSM) under Central Composite Design (CCD). The effect of lignin peroxidase (LiP) on the biodegradation was also monitored and it was partially purified as well as characterized.  The screening experiments showed that this fungus has higher biodegradation potential for disperse dyes (red S3B 75.25% & yellow SRLB 68.9% as compared to direct dyes (pink B= 33.53% & yellow BG= 32.1%). The biodegradation of disperse dyes was optimized by studying effect of growth parameters and nutritional parameters. The biodegradation of red S3B increased to 93.1% while biodegradation of yellow SRLB increased to 89.37% after optimization. Study of lignin peroxidase (LiP) confirmed its active role in biodegradation with its observed activities 89.33 IU/mL/min and 88.54 IU/mL/min during biodegradation of disperse red S3B & yellow SRLB, respectively. It was partially purified in the presence of 60 % ammonium sulfate, having optimum pH= 4.5 and temperature 30 ⁰C. The LiP of P. ostreatus is quite active (Vmax= 277.7 mM/mL/min) ligninolytic enzyme and has good affinity for Azure B (Km=0.328 µM). 

Key Words: Pleurotus ostreatus, dyes biodegradation, response surface methodology, lignin peroxidase