45348-G4
Investigating the Relationship between Characteristics of Heterogeneous Cellulose and Cellulase Activities
Technical Report for ACS Petroleum Research Foundation
PRF# 45348-G4 (09/2006-08/2008)
Y.-H. Percival Zhang, August 25, 2008 Cellulose is the most abundant renewable resource (ca. 1x1011 tons/year). Heterogeneous cellulose hydrolysis expedited by cellulases -- endoglucanase, exoglucanase, and beta-glucosidase -- plays an important role in the global carbon cycle, is important in agricultural processes and waste pretreatment, and will be an important part of emerging biobased products and biofuels industries. The production of chemicals and energy from renewable cellulosic materials is vital to sustainable development of human beings because it reduces reliance on non-renewable fossil fuels, decreases emission of greenhouse gases, and offers benefits to the national interests. In the proposal, I planned to investigate the characterization of heterogeneous cellulose properties impacting enzymatic cellulose hydrolysis. With the help of this award, we have developed a nano-scale tool (recombinant protein) containing a green fluorescent protein and cellulose-binding module. The adsorption of this protein will be used to more accurately represent cellulose accessibility to cellulase than other technologies. The paper has been published in Langmuir [1]. In the second year, we have further improved CAC assay for pretreated lignocellulosic biomass [2]. Quantitative determinations of the total substrate accessibility to cellulase (TSAC) and cellulose accessibility to cellulase (CAC) based on adsorption of a non-hydrolytic recombinant protein TGC were for the first time established without and with blocking of bovine serum album, respectively. The COSLIF-pretreated corn stover had a CAC of 11.57 m2/g, nearly twice of that of the dilute acid (DA)-pretreated biomass (5.89 m2/g). All results suggest that CSLF can break lignocellulose structure more efficiently than can DA, resulting in more CAC accompanied by faster hydrolysis rates and higher sugar digestibility. In addition, increasing CAC could be more efficient to enhance hydrolysis rates and digestibility rather than removing lignin for corn stover. The manuscript is under preparation and internal review. In a word, I appreciated the support from ACS PFR. Through this support, I have established a solid foundation for my future career development. I have received several awards during the past two years: such as DuPont Young Professor Award, Air Force Young Investigator Award, Outstanding New Faculty Award of COE of Virginia Tech, to name a few. References ADDIN EN.REFLIST 1. Hong J, Ye X, Zhang YHP: Quantitative determination of cellulose accessibility to cellulase based on adsorption of a nonhydrolytic fusion protein containing CBM and GFP with its applications. Langmuir 2007, 23:12535-12540. 2. Zhu Z, Sathitsuksanoh N, Schell DJ, McMillan JD, Zhang Y-HP: Comparative study of corn stover pretreated by dilute acid and cellulose solvent-based lignocellulose fractionation: Enzymatic hydrolysis, supramolecular structure, and substrate accessibility. In preparation 2008.
