Monday, May 5, 2008
7-07

Production of Ligninase from Wheat Straw Using a Pelletized Phanerochaete chrysosposium Culture

Wei Liao1, Yan Liu1, Zhimin Li2, and Shulin Chen3. (1) Department of Biosystems and Agricultural Engineering, Michigan State University, 202 Farrall Hall, East Lansing, MI 48824, (2) Biological Systems Engineering, Washington State University, 213 L.J. Smith Hall, Pullman, WA 99163, (3) Department of Biological System Engineering, Washington State University, L.J. Smith 213, Pullman, WA 99163

White rot fungus Phanerochaete chrysosposium is a well known filamentous fungus that can deconstruct lignocellulosic materials by excreting extracellular oxidative enzymes, such as lignin peroxidase, manganese peroxidase. As a filamentous fungus, the morphology of P. chrysospsium could be clump-type or pellet-type. The clump morphology increases the viscosity of the medium, wraps around baffles and impellers which influence the nutrient mass transfer and reactor performance. The situation would be more significant for ligninase production using P. chrysosposium because ligninase synthesis needs high O2 tension and low shear stress. Using pelletized fungi can alleviate the problems. Pelletization of filamentous fungi makes it possible not only to improve the nutrients mass transfer, but also to increase significantly oxygen concentration and to reduce the shear stress. In addition, another obstacle to commercial production of ligninases is the cost of chemical defined cultural medium. Our results indicated that ligninase can be produced from pelletized morphology using wheat straw as sole nutrient. In this paper, ligninase production from clump morphology and pellet morphology is first compared. The effects of medium composition such as wheat straw, mineral salts, pH, and nitrogen sources are then studied on pelletized fungal culture in order to maximize the ligninase production from wheat straw.

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