Abstract:

A fungus producing laccase was screened from dyeing wastewater and was identified as Geotrichum candidum （ G. candidum） M3. Then, the production conditions of laccase from G. candidum M3 and the decoloration ability of laccase for azo dyes were investigated. The results show that （ 1 ） glucose and ammonium chloride are respectively the best carbon and nitrogen sources for the production of laccase from G. candidum M3 ; （2） the optimal contents of glucose, ammonium chloride, guaiacol and copper sulfate for culturing laccase are respectively 2 g/L, 1.5 g/L, 0. 015 mmol/L and 0. 05 mmol/L; （ 3 ） the highest activities of laccase produced from G. candidum M3 under optimal conditions in a 5-L mechanically-stirred fermentor and a 7-L air-lift fermentor reach 23.8 and 36. 9μmol/（s· L）, respectively; （4） the air-lift fermentor is more suitable for the laccase production from G. candidum M3 ; and （5） after a treatment with the produced crude laccase for 1.5 h, the decoloration rate of azo dyes reaches 90. 2%. The decoloration ability of the produced laccase for azo dyes is also proved by Vis-UV spectrum.

Key words: Geotrichum candidum, laccase, azo dye, decoloration