Pretreatment of Agro-Industrial Wastes with Basidial Fungi Strains for Effective Delignification of Lignocellulosic Wastes

Lignocellulosic biomass, including agro-industrial wastes, is an ideal cheap and abundant source of glucose for ethanol production. The complex structure of lignin makes it difficult to hydrolyze the biomass cellulose to sugars and other organic compounds. In recent years, it has become more and more important to develop an environmentally friendly pretreatment method for delignification of plant residues. The aim of the present work was to study the delignification of agro-industrial residues by higher basidial fungi. Solid state fermentation (SSF) of 35 tested strains on wheat, rice and corn straw, potato above-ground mass (AMP) and sunflower lignocellulosic waste (SLW) showed different levels of oxidase enzyme production. In particular, laccase activity varied from 0.5 to 91.8 U/ml, and manganese peroxidase (MnP) activity from 0 to 2.1 U/ml, depending on the substrates and the type of the fungi. The best lignin destroyers were: Trametes maxima GK-02, Ganoderma sp. GV 51, Pleurotus sp. IN-93. The best delignification result was achieved with the strain Pleurotus sp. IN-93 in corn straw and wheat straw, from 17.8% to 7.7% and from 19.1% to 10.6%, respectively. In the case of delignification of the AMP, the amount of lignin decreased by 4.0-6.9%. Trametes maxima GK-02 was the most effective in case of SLW - lignin degradation from 19.7% to 10.6%.