Modeling the Effect of pH and Temperature for Cellulases Immobilized on Enzymogel Nanoparticles
- 314 Downloads
Production costs of cellulosic biofuels can be lowered if cellulases are recovered and reused using particulate carriers that can be extracted after biomass hydrolysis. Such enzyme recovery was recently demonstrated using enzymogel nanoparticles with grafted polymer brushes loaded with cellulases. In this work, cellulase (NS50013) and β-glucosidase (Novozyme 188) were immobilized on enzymogels made of poly(acrylic acid) polymer brushes grafted to the surface of silica nanoparticles. Response surface methodology was used to model effects of pH and temperature on hydrolysis and recovery of free and attached enzymes. Hydrolysis yields using both enzymogels and free cellulase and β-glucosidase were highest at the maximum temperature tested, 50 °C. The optimal pH for cellulase enzymogels and free enzyme was 5.0 and 4.4, respectively, while both free β-glucosidase and enzymogels had an optimal pH near 4.4. Highest hydrolysis sugar concentrations with cellulase and β-glucosidase enzymogels were 69 and 53 % of those with free enzymes, respectively. Enzyme recovery using enzymogels decreased with increasing pH, but cellulase recovery remained greater than 88 % throughout the operating range of pH values less than 5.0 and was greater than 95 % at pH values below 4.3. Recovery of β-glucosidase enzymogels was not affected by temperature and had little impact on cellulase recovery.
KeywordsImmobilized enzymes Enzymatic hydrolysis Cellulase Enzyme recovery Response surface methodology Enzymogel
International Union of Pure and Applied Chemistry
Response surface methodology
Analysis of variance
High-performance liquid chromatography
Bovine serum albumin
Funding for this research was provided by the National Science Foundation (Arlington, VA) under grant numbers CBET 0966526 and CBET 0966574.
- 15.Samaratunga, A., Kudina, O., Nahar, N., Zakharchenko, A., Minko, S., Voronov, A., & Pryor, S. W. (2015). Impact of enzyme loading on the efficacy and recovery of cellulolytic enzymes immobilized on enzymogel nanoparticles. Applied Biochemistry and Biotechnology, 175, 2872–2882.CrossRefGoogle Scholar
- 17.de Souza, C. J. A., Costa, D. A., Rodrigues, M. Q. R. B., dos Santos, A. F., Lopes, M. R., Abrantes, A. B. P., dos Santos Costa, P., Silveira, W. B., Passos, F. M. L., & Fietto, L. G. (2012). The influence of presaccharification, fermentation temperature and yeast strain on ethanol production from sugarcane bagasse. Bioresource Technology, 109, 63–69.CrossRefGoogle Scholar
- 18.López-Linares, J. C., Romero, I., Cara, C., Ruiz, E., Castro, E., & Moya, M. (2014). Experimental study on ethanol production from hydrothermal pretreated rapeseed straw by simultaneous saccharification and fermentation. Journal of Chemical Technology & Biotechnology, 89, 104–110.CrossRefGoogle Scholar
- 21.Jeng, W.-Y., Wang, N.-C., Lin, M.-H., Lin, C.-T., Liaw, Y.-C., Chang, W.-J., Liu, C.-I., Liang, P.-H., & Wang, A. H. J. (2011). Structural and functional analysis of three β-glucosidases from bacterium Clostridium cellulovorans, fungus Trichoderma reesei and termite Neotermes koshunensis. Journal of Structural Biology, 173, 46–56.CrossRefGoogle Scholar
- 23.Ghose, T. K. (1987). Measurement of cellulase activities. Pure and Applied Chemistry, 59, 257–268.Google Scholar
- 30.Balsan, G., Astolfi, V., Benazzi, T., Meireles, M. A. A., Maugeri, F., Di Luccio, M., Dal Pra, V., Mossi, A. J., Treichel, H., & Mazutti, M. A. (2012). Characterization of a commercial cellulase for hydrolysis of agroindustrial substrates. Bioprocess and Biosystems Engineering, 35, 1229–1237.CrossRefGoogle Scholar