title: A process for energy-efficient high-solids fed-batch enzymatic liquefaction of cellulosic biomass.
abstract: The enzymatic hydrolysis of cellulosic biomass is a key step in the biochemical production of fuels and chemicals. Economically feasible large-scale implementation of the process requires operation at high solids loadings, i.e., biomass concentrations >15% (w/w). At increasing solids loadings, however, biomass forms a high viscosity slurry that becomes increasingly challenging to mix and severely mass transfer limited, which limits further addition of solids. To overcome these limitations, we developed a fed-batch process controlled by the yield stress and its changes during liquefaction of the reaction mixture. The process control relies on an in-line, non-invasive magnetic resonance imaging (MRI) rheometer to monitor real-time evolution of yield stress during liquefaction. Additionally, we demonstrate that timing of enzyme addition relative to biomass addition influences process efficiency, and the upper limit of solids loading is ultimately limited by end-product inhibition as soluble glucose and cellobiose accumulate in the liquid phase.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Davis, One Shields Ave, Davis, CA 95616, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Cardona
authors.affiliation: Aspect Imaging, One Shields Ave, Davis, CA 95616, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Tozzi
authors.affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Ave, Davis, CA 95616, USA.
authors.forename: N
authors.initials: N
authors.lastname: Karuna
authors.affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Ave, Davis, CA 95616, USA. Electronic address: tjeoh@ucdavis.edu.
authors.forename: T
authors.initials: T
authors.lastname: Jeoh
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Davis, One Shields Ave, Davis, CA 95616, USA; Department of Food Science and Technology, University of California, Davis, One Shields Ave, Davis, CA 95616, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Powell
authors.affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Ave, Davis, CA 95616, USA; Department of Food Science and Technology, University of California, Davis, One Shields Ave, Davis, CA 95616, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: McCarthy
mesh_terms: D061249:Batch Cell Culture Techniques; D056804:Biofuels; D018533:Biomass; D001709:Biotechnology / Q000295:instrumentation / Q000379:methods*; D002475:Cellobiose / Q000737:chemistry / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry / Q000378:metabolism*; D004798:Enzymes / Q000737:chemistry / Q000378:metabolism; D005947:Glucose / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D012212:Rheology / Q000295:instrumentation / Q000379:methods
chemical_list: D056804:Biofuels; D004798:Enzymes; D002475:Cellobiose; D002482:Cellulose; D005947:Glucose
keywords: Enzymatic hydrolysis; Fed-batch; Liquefaction; Magnetic resonance imaging; Rheology