Sunday, April 29, 2007

Enhance the production of ligninases using a pelletized Phanerochaete chrysosposium culture

Wei Liao1, Yan Liu2, and Shulin Chen2. (1) Department of Biosystems and Agricultural Engineering, Michigan State University, 202 Farrall Hall, East Lansing, MI 48824, (2) 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 solve 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.  Consequently, the pelletization technology will enhance the reactor performance by increasing ligninolytic enzyme productivity. In this presentation, ligninase production from clump morphology and pellet morphology will be first compared. The effects of biomass concentration, minimal oxygen tension, agitation, and medium composition on ligninase production will be then presented. Finally, the optimal culture conditions for ligninase production using pelletized P. chrysosporium culture will be concluded.