17-29: Separating the effects of enzymes and mediators in lignin depolymerization

Monday, April 29, 2013
Exhibit Hall
Michael Kent1, Dong Wu1, Heins Richard1, Briana Vernon2, Kenneth Sale1, Seema Singh1 and Blake Simmons1, (1)Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA, (2)Sandia National Laboratories, Albuquerque
Depolymerization of lignin by white rot fungi is known to involve enzymes (laccases, lignin peroxidases, and manganese peroxidases) as well as small molecules that function as mediators.  The mediators are each activated by an enzyme and are believed to diffuse into dense cell wall structures to access and depolymerize lignin.  In this work we used quartz crystal microbalance monitoring, atomic force microscopy, and vibrational spectroscopy to investigate the effects of three enzyme/mediator couples on films of pure lignin:  laccase and ABTS, lignin peroxidase and veratryl alcohol, and manganese peroxidase and Mn+3.  For each enzyme/mediator couple we measured the effects of the enzyme alone, the activated mediator alone, and the enzyme and mediator together.  For each case we report the extent of adsorption of enzyme or mediator onto the lignin, the loss of lignin mass from the film with time, changes in surface topography, and changes in chemical bonding.