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Physicochemical structural changes of cellulosic substrates during enzymatic saccharification
| Content Provider | Semantic Scholar |
|---|---|
| Author | Meng, Xianzhi Ragauskas, Arthur J. |
| Copyright Year | 2018 |
| Abstract | Converting renewable lignocellulosic substrates such as biomass to biofuel has drawn tremendous amount of attention due to the growing concerns about environmental stewardship and diminishing availability of fossil fuels.1 Currently, the bioconversion process involves several steps: size reduction, pretreatment, hydrolysis, fermentation and distillation/purification. Pretreatment is known to increase cellulose accessibility by changing the chemical composition and physical structures of biomass plant cell wall and numerous physical or chemical pretreatments have been widely studied and reviewed in recent literatures.2–4 Enzymatic hydrolysis represents a process in which polysaccharides are effectively broken down to its corresponding sugar monomers by using a multi-component enzyme system and this is a very slow process in most cases due to the complex characteristics of lingocellulosics to protect its polysaccharides from de-polymerization. Years of research efforts have been tried to correlate the changes of substrate factors caused by pretreatment to the changes in biomass recalcitrance reflected by the sugar yield after hydrolysis, however the exact molecular mechanisms of biomass recalcitrance are still not well-understood and much of the literature has reported inconsistent results.5 There is no doubt that the initial hydrolysis rate or the final hydrolysis yield is influenced by physicochemical structural features of lignocellulosic substrates. It has been reported that low cellulose degree of polymerization (DP), crystallinity (CrI), lignin content and high cellulose accessible surface area favor enzymatic hydrolysis.6–9 On the other hand, a rapid decrease in the conversion rate was repeated observed as the hydrolysis time extended. The exact mechanism leading to this rate decrease is not fully clear due to the complexity of the lignocellulosic substrate and enzymatic hydrolysis system. Some studies have reported that the increased recalcitrance or the decreased reactivity of the substrate during hydrolysis was the major reason causing the gradual decrease of hydrolysis rate, while others suggested that negative mode of enzyme action such as inactivation, diffusion constraints and jamming were the potential factors to be responsible.10 Thus, this review focuses on the recent advances in understanding of limitations occurring during enzymatic hydrolysis that might be responsible for the gradual slowing down of the reaction, which will be extremely helpful to strengthen the understanding of intrinsic hydrolysis reaction mechanisms. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://medcraveonline.com/JABB/JABB-01-00015.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Accessibility Accessible surface area Biofuels Biomass CELLULASE Cell Wall Cellulose Conversion marketing Design of experiments Distillation Dyspnea on exertion Emoticon Ethanol FOSSIL Infant, Extremely Premature Interaction Lignin Manuscripts Numerous Plant Cells Polysaccharides Purification of quantum state Radio jamming Scientific Publication Sugars World Wide Web large latent transforming growth factor-beta complex monomer |
| Content Type | Text |
| Resource Type | Article |
