The effect of different agriculture waste polysaccharides as an only carbon source in culture medium of wood–degrading basidiomycete Cerrena unicolor C–139 were investigated. The maximal growth and laccase synthesis in shaken flask was observed in mineral salts broth containing potato starch as the carbon source and asparagine as the nitrogen source (11,000 nkat/L). When an optimized medium was stimulated by addition of 10 μM Cu^ to the culture medium on days 3–5 the maximal activity 24,000 nkt/L was obtained. Next the influence of the stabilization of the medium pH after 48–h incubation on laccase activity in fermentor cultures had to be estimated. The obtained data show that use of an automatic pH control set at pH 5.0 increased laccase productivity significantly (by 12 times) as compared to that obtained in the fermentor culture with a non–stabilized pH–value. Under the new conditions, the highest enzyme activity of 290,000 nkat/L was reached after 13–day incubation.