Countercurrent enzymatic saccharification of cellulosic biomass

Zentay, Agustin N.; Liang, Chao; Lonkar, Sagar; Holtzapple, Mark T.

doi:10.1016/j.biombioe.2016.03.033

Cited by 10 publications

(17 citation statements)

References 3 publications

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“…The substrate used for all experiments was α-cellulose (Sigma-Aldrich, C8002). Compositional analysis showed that the substrate contained glucan 78.5% and xylan 14.4% [11].…”

Section: Methodsmentioning

confidence: 99%

“…The enzyme used in this study was Novozymes Cellic ® CTec2 (lot# VCPI 0007), a blend of aggressive cellulases with high levels of β-glucosidases and hemicellulases that degrade lignocellulose into sugars [12]. The protein concentration was determined to be 294 mg protein/mL with Pierce BCA assay [11]. Before use, the enzyme solution was diluted ten times with deionized (DI) water.…”

Section: Methodsmentioning

confidence: 99%

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Development of modified HCH-1 kinetic model for long-term enzymatic cellulose hydrolysis and comparison with literature models

Liang

Raftery

et al. 2019

Biotechnol Biofuels

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Background Enzymatic hydrolysis is a major step for cellulosic ethanol production. A thorough understanding of enzymatic hydrolysis is necessary to help design optimal conditions and economical systems. The original HCH-1 (Holtzapple–Caram–Humphrey–1) model is a generalized mechanistic model for enzymatic cellulose hydrolysis, but was previously applied only to the initial rates. In this study, the original HCH-1 model was modified to describe integrated enzymatic cellulose hydrolysis. The relationships between parameters in the HCH-1 model and substrate conversion were investigated. Literature models for long-term (> 48 h) enzymatic hydrolysis were summarized and compared to the modified HCH-1 model. Results A modified HCH-1 model was developed for long-term (> 48 h) enzymatic cellulose hydrolysis. This modified HCH-1 model includes the following additional considerations: (1) relationships between coefficients and substrate conversion, and (2) enzyme stability. Parameter estimation was performed with 10-day experimental data using α-cellulose as substrate. The developed model satisfactorily describes integrated cellulose hydrolysis data taken with various reaction conditions (initial substrate concentration, initial product concentration, enzyme loading, time). Mechanistic (and semi-mechanistic) literature models for long-term enzymatic hydrolysis were compared with the modified HCH-1 model and evaluated by the corrected version of the Akaike information criterion. Comparison results show that the modified HCH-1 model provides the best fit for enzymatic cellulose hydrolysis. Conclusions The HCH-1 model was modified to extend its application to integrated enzymatic hydrolysis; it performed well when predicting 10-day cellulose hydrolysis at various experimental conditions. Comparison with the literature models showed that the modified HCH-1 model provided the best fit. Electronic supplementary material The online version of this article (10.1186/s13068-019-1371-5) contains supplementary material, which is available to authorized users.

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“…The substrate used for all experiments was α-cellulose (Sigma-Aldrich, C8002). Compositional analysis showed that the substrate contained glucan 78.5% and xylan 14.4% [11].…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Development of modified HCH-1 kinetic model for long-term enzymatic cellulose hydrolysis and comparison with literature models

Liang

Raftery

et al. 2019

Biotechnol Biofuels

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“…Conventionally, batch saccharification process is considered as time taking as common time duration is 3-7 days and high solid loading is required in that process to achieve acceptable conversions (Selig 2008). As an suitable alternative to batch saccharification, continuous countercurrent saccharification was proposed by Zentay et al (2016) while working with commercial α-cellulose. As the utilization of commercial enzyme in saccharification process is considered as expensive, production of enzymes from cheap substrate, immobilization of enzymes, and recycle and reuse of the enzymes are alternative solutions to make the enzymatic saccharification process commercially more viable.…”

Section: Hydrolysis Methodsmentioning

confidence: 99%

Lignocellulosic bioethanol production: prospects of emerging membrane technologies to improve the process – a critical review

Dey

Pal

Kevin

et al. 2018

Reviews in Chemical Engineering

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AbstractTo meet the worldwide rapid growth of industrialization and population, the demand for the production of bioethanol as an alternative green biofuel is gaining significant prominence. The bioethanol production process is still considered one of the largest energy-consuming processes and is challenging due to the limited effectiveness of conventional pretreatment processes, saccharification processes, and extreme use of electricity in common fermentation and purification processes. Thus, it became necessary to improve the bioethanol production process through reduced energy requirements. Membrane-based separation technologies have already gained attention due to their reduced energy requirements, investment in lower labor costs, lower space requirements, and wide flexibility in operations. For the selective conversion of biomasses to bioethanol, membrane bioreactors are specifically well suited. Advanced membrane-integrated processes can effectively contribute to different stages of bioethanol production processes, including enzymatic saccharification, concentrating feed solutions for fermentation, improving pretreatment processes, and finally purification processes. Advanced membrane-integrated simultaneous saccharification, filtration, and fermentation strategies consisting of ultrafiltration-based enzyme recycle system with nanofiltration-based high-density cell recycle fermentation system or the combination of high-density cell recycle fermentation system with membrane pervaporation or distillation can definitely contribute to the development of the most efficient and economically sustainable second-generation bioethanol production process.

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“…Using α-cellulose, Zentay [55] reported that to achieve a given glucan conversion, countercurrent saccharification reduces enzyme loadings by 8 to 20.5 times compared to batch saccharification. At an enzyme loading of 10 FPU/g cellulose (~20 mg enzyme/g cellulose), enzymes cost contribute $0.68 to $1.47/gal ethanol, when the cost of cellulose enzyme is $10/kg [56].…”

Section: Introductionmentioning

confidence: 99%

“…Volatile antimicrobials can be recovered and re-used during the sugar concentration step following countercurrent saccharification, thereby reducing costs and making the process safe ( Figure 5.1). Chloroform has been shown to be an effective volatile antimicrobial for use in countercurrent saccharification [55]. It is easily available and is commonly used to maintain sterility in microbiology labs.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Shock Pretreatment of Corn Stover Using the Carboxylate Platform

Darvekar

Holtzapple

2015

Appl Biochem Biotechnol

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Corn stover was pretreated with lime and shock, a mechanical process that uses a shockwave to alter the biomass structure. Two pretreatments (lime-only and lime + shock) were evaluated using enzymatic hydrolysis, batch mixed-culture fermentations, and continuous countercurrent mixed-culture fermentation. In a 120-h enzymatic hydrolysis, shock pretreatment increased the glucan digestibility of submerged lime pretreatment (SLP) corn stover by 3.5 % and oxidative lime pretreatment (OLP) corn stover by 2.5 %. The continuum particle distribution model (CPDM) was used to simulate a four-stage continuous countercurrent mixed-culture fermentation using empirical rate models obtained from simple batch experiments. The CPDM model determined that lime + shock pretreatment increased the total carboxylic acids yield by 28.5 % over lime-only pretreatment in a countercurrent fermentation with a volatile solids loading rate (VSLR) of 12 g/(L/day) and liquid retention time (LRT) of 30 days. In a semi-continuous countercurrent fermentation performed in the laboratory for 112 days with a VSLR of 1.875 g/(L day) and LRT of 16 days, lime + shock pretreatment increased the total carboxylic acid yield by 14.8 %. The experimental results matched closely with CPDM model predictions (4.05 % error).

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Countercurrent enzymatic saccharification of cellulosic biomass

Cited by 10 publications

References 3 publications

Development of modified HCH-1 kinetic model for long-term enzymatic cellulose hydrolysis and comparison with literature models

Development of modified HCH-1 kinetic model for long-term enzymatic cellulose hydrolysis and comparison with literature models

Lignocellulosic bioethanol production: prospects of emerging membrane technologies to improve the process – a critical review

Assessment of Shock Pretreatment of Corn Stover Using the Carboxylate Platform

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