(563c) Effect of Bsa Treatment of Cellulosic Biomass on Batch and Continuous Enzymatic Hydrolysis

Authors: 
Brethauer, S., University of California Riverside
Studer, M., University of California Riverside
Yang, B., University of California Riverside
Wyman, C. E., University of California, Riverside


The addition of BSA as a model non-catalytic protein has been shown to enhance the cellulose hydrolysis rate and reduce the amount of enzyme needed to reach a certain conversion. Furthermore, continuous processes are generally favored for producing fuels such as ethanol as well as commodity chemicals, but data on continuous biological processing of lignocellulosic biomass are scarce.

In this study, we investigated the influence of BSA concentration on the hydrolysis rate for both acid pretreated corn stover and pure cellulose (Avicel) as well as the influence of reaction temperature in batch experiments. For Avicel, the 72 h hydrolysis yield could be enhanced by 20% by addition of only 0.5 g/L BSA but only at a temperature of 50°C and not at 38°C, the common SSF temperature. For acid pretreated corn stover, a hydrolysis yield of 85% could be reached in the presence of 20 g/L BSA with a cellulase loading of only 2.5 FPU/g cellulose, corresponding to an improvement of 25% relative to the control experiment. In addition, this effect could be maintained at a hydrolysis temperature of 38°C, indicating that two different mechanisms are likely responsible for hydrolysis yield improvements with corn stover and Avicel, which will be further investigated and discussed. A continuous hydrolysis system was set up to investigate the influence of BSA addition, and stable steady state glucose concentrations were achieved, proving the air bubble feeding mode prevented settling of solid biomass in the feeding tube. For both substrates, the benefits of BSA were more pronounced in continuous runs, leading to 30 to 40% higher glucose yields.