Improvement of Preferential Lignin Degradation By Pleurotus-ostreatus

The global commercial production of Plcrrrotus amounts to about 900.0w) tones annually, with production second only to Aguricro . Large amounts of spent rau materials are a by-product of this industry. The prxucal utilization of the polysscchandes of the Iignocellulosic complex is limited due to the high content of lignin. The focus of this study is on the effect of manganese on preferential biodegradation of lignin during solid state fermentation by Pleurorus ostrcutu.7 The effects of manganese (at concentrations of 0 to 2.7 mMj on the production of extracellular enrymes involved in ligninolysis by P usrreufu.7 here studied during chemically defined, solid-state fermentation. Mn wab found to precipitate in a11 treatment>. Physiological activities of the fungus expressed as glucose consumption and C02 evolution peaked during the fir\[ week of fermentation. and were not affected by Mn level. Laccase, Mn peroxidase and cstalase activities. and H.0. production uere all affected by Mn level. albeit differently In general. the specific enzymes involved in ligninolysis uere enhanccd by increasing concentrations of Mn during the secondary growth phase. Degradation of (I.'Cllignin prepared from cotton branches to holuble products, as well a\ its mineralization to "Cq. was enhanced by the addition of Mn. Degradation of [ llClcellulose uai not affected by the addition of Mn. Cotton stalks usre amended with Mn(l1) at ConcentrMion range ot 30 to 620 pg Mnl g.d.u.. and fermented with P. osfreurus. Enhancement of selectivity was demonstrated by analyring the residual matter at the end of the fermentation periud using crude fiber analysis The cellulohe fraction in the original mstter was 1.8 times higher than lignin. This ratio (cel1ulose:lignin) doubled dunng the 32 days of SSF, from 3 0 in the control to 5.6 and 6.6. iollowing the addition of .Mn to the medium. Enhancement of selective lignin degradation could be the result of either increasing the activities of ligninolytic enzymes or producing Mn(lI1). which might preferentially degrade aromatic structures in the lignocellulosic complex.