Rajeev Kumar¹, Charles E. Wyman²
                                        1084 Columbia Avenue,
                           CE-CERT, Bourns School of Engineering
                     University of California Riverside, Riverside-92507, CA
                                                      (951) 781-5703 phone
      (951) 781-5790 fax
                                              cewyman@engr.ucr.edu
                                         ¹Thayer School of Engineering, Dartmouth College, NH
                                        ²University of California, Riverside, CA

As part of the cooperative CAFI research to evaluate the performance of leading pretreatment technologies, the digestibilities of solids prepared by ammonia fiber expansion, ammonia recycle percolation, controlled pH, dilute acid, lime, and sulfur dioxide pretreatments are being evaluated at different cellulase loadings for two distinct types of cellulosic biomass from controlled sources: an agricultural residue, corn stover, and a woody biomass, poplar.  Single batches of commercial enzymes from Genencor International are being used along with standard experimental protocols.  The impact of optimum conditions of these leading pretreatments on the characteristics previously thought to be responsible for good digestibility of the solids produced is being evaluated and related to the observed performance.  In addition, the possibility of further reducing cellulase usage is being determined using catalytic binding domains of cellulases (obtained by Papain digestion), different combinations of cellulase and xylanase enzymes, and addition of additives including BSA, surfactants, and polymers. 

 Keywords –pretreatment, substrate, digestibility, cellulase