(290b) Synergistic Interactions Between Fungal and Bacterial Glycosyl Hydrolases On Ammonia Fiber Expansion Treated Corn Stover

Authors: 
Gao, D., Michigan State University
Chundawat, S. P. S., Michigan State University
Dale, B. E., Great Lakes Bioenergy Center, Michigan State University
Balan, V., Great Lakes Bioenergy Center, Michigan State University


With the depletion of non-renewable petroleum reserves, producing biofuels and biochemicals from biomass has been given significant attention to help transform the existing petroleum based economy to bio-based one. Lignocellulosic biomass provides an abundant resource for the sustainable production of fuels and chemicals. However, the high cost of hydrolytic enzymes is one of the major factors impeding the implementation of an economically viable lignocellulosic biorefinery. In order to significantly reduce enzyme loading during hydrolysis one should have a fundamental understanding of how the enzymes interact synergistically with each other. Some of these cellulases and hemicellulases include endoglucanases (EG), endoxylanases (EX), cellobiohydrolases I and II (CBH I and II), ß-glucosidases (ßG) and ß-xylosidases (ßX).

In this study, we evaluate both enzyme adsorption and hydrolysis of Ammonia Fiber Expansion treated corn stover by different combinations of enzymes from fungal and bacterial sources. CBH I, CBH II and EG I are purified from commercial enzyme Spezyme CP, ßG is purified from Novozyme 188. Two cellulases (LC1 and LC2), two xylanase (LX1 and LX2), one ß-glucosidases (LßG) and one ß-xylosidases (LßX) are from bacterial sources provided by Lucigen. The results show that bacterial hemicellulases work synergistically with fungal cellulases by increasing both glucose and xylose yields. Further studies were carried out using 73 different mixtures of the fungal and bacterial enzymes, based on a statistical design of mixtures, to determine optimal ratios of enzymes that maximized glucose and xylose yields. The mixtures loaded at 3 different total protein loadings (10, 15 and 30 mg/g glucan) helped reconfirm the synergistic interactions between the bacterial hemicellulases and fungal cellulases. These results depict the possibility of designing an optimal mixture of enzymes to maximize hydrolysis yields which could help decrease total enzyme usage and reduce bio-fuel production costs.