Recent developments in pretreatment technologies on lignocellulosic biomass: Effect of key parameters, technological improvements, and challenges

Bhatia, Shashi Kant; Jagtap, Sujit Sadashiv; Bedekar, Ashwini Ashok; Bhatia, Rajendra; Patel, Anil Kumar; Pant, Deepak; Banu, J. Rajesh; Rao, Christopher V.; Kim, Yun Gon; Yang, Yung Hun

doi:10.1016/j.biortech.2019.122724

Cited by 531 publications

(212 citation statements)

References 139 publications

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“…In this physical process, high pressure saturated steam is used to heat the lignocellulosic biomass for 2-10 min at temperatures typically in the range of 180-230 • C. Chemical processes can be carried out employing acid (e.g., H 2 SO 4 , HCl) or alkaline solutions such as different hydroxides, and these kinds of treatment require milder conditions of temperature [49]. Detailed information about the current pretreatment strategies of lignocellulosic biomass is reviewed elsewhere [50,51].…”

Section: Challenges Of Cellulases Cocktailsmentioning

confidence: 99%

Engineering Robust Cellulases for Tailored Lignocellulosic Degradation Cocktails

Contreras

Pramanik

Рожкова

et al. 2020

IJMS

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Lignocellulosic biomass is a most promising feedstock in the production of second-generation biofuels. Efficient degradation of lignocellulosic biomass requires a synergistic action of several cellulases and hemicellulases. Cellulases depolymerize cellulose, the main polymer of the lignocellulosic biomass, to its building blocks. The production of cellulase cocktails has been widely explored, however, there are still some main challenges that enzymes need to overcome in order to develop a sustainable production of bioethanol. The main challenges include low activity, product inhibition, and the need to perform fine-tuning of a cellulase cocktail for each type of biomass. Protein engineering and directed evolution are powerful technologies to improve enzyme properties such as increased activity, decreased product inhibition, increased thermal stability, improved performance in non-conventional media, and pH stability, which will lead to a production of more efficient cocktails. In this review, we focus on recent advances in cellulase cocktail production, its current challenges, protein engineering as an efficient strategy to engineer cellulases, and our view on future prospects in the generation of tailored cellulases for biofuel production.

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Section: Challenges Of Cellulases Cocktailsmentioning

confidence: 99%

Engineering Robust Cellulases for Tailored Lignocellulosic Degradation Cocktails

Contreras

Pramanik

Рожкова

et al. 2020

IJMS

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“…Common pretreatment methods include acid treatment, alkali treatment, organosolv treatment, automated hydrolysis treatment, steam explosion treatment, etc. [4]. Among these pretreatment methods, alkali pretreatment is widely used due to the advantages of non-corrosive, non-toxic, and efficient delignification [5,6].…”

mentioning

confidence: 99%

Alkaline organosolv pretreatment of different sorghum stem parts for enhancing the total reducing sugar yields and p-coumaric acid release

Long

Ding

2020

Biotechnol Biofuels

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Background: The sorghum stem can be divided into the pith and rind parts with obvious differences in cell type and chemical composition, thus arising the different recalcitrance to enzyme hydrolysis and demand for different pretreatment conditions. The introduction of organic solvents in the pretreatment can reduce over-degradation of cellulose and hemicellulose, but significance of organic solvent addition in pretreatment of different parts of sorghum stem is still unclear. Valorization of each component is critical for economy of sorghum biorefinery. Therefore, in this study, NaOH-ethanol pretreatment condition for different parts of the sorghum stem was optimized to maximize p-coumaric acid release and total reducing sugar recovery. Result: Ethanol addition improved p-coumaric acid release and delignification efficiency, but significantly reduced hemicellulose deconstruction in NaOH-ethanol pretreatment. Optimization using the response surface methodology revealed that the pith, rind and whole stem require different NaOH-ethanol pretreatment conditions for maximal p-coumaric acid release and xylan preservation. By respective optimal NaOH-ethanol pretreatment, the p-coumaric acid release yields reached 94.07%, 97.24% and 95.05% from pith, rind and whole stem, which increased by 8.16%, 8.38% and 8.39% compared to those of NaOH-pretreated samples. The xylan recoveries of pith, rind and whole stem reached 76.80%, 88.46% and 85.01%, respectively, which increased by 47.75%, 15.11% and 35.97% compared to NaOH pretreatment. Adding xylanase significantly enhanced the enzymatic saccharification of pretreated residues. The total reducing sugar yields after respective optimal NaOH-ethanol pretreatment and enzymatic hydrolysis reached 84.06%, 82.29% and 84.09% for pith, rind and whole stem, respectively, which increased by 29.56%, 23.67% and 25.56% compared to those of NaOH-pretreated samples. Considering the separation cost of the different stem parts, whole sorghum stem can be directly used as feedstock in industrial biorefinery. Conclusion: These results indicated that NaOH-ethanol is effective for the efficient fractionation and pretreatment of sorghum biomass. This work will help to understand the differences of different parts of sorghum stem under NaOH-ethanol pretreatment, thereby improving the full-component utilization of sorghum stem.

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“…[1]. In recent decades numerous research papers have addressed the use of lignocellulose materials to obtain ethanol through biochemical routes [2][3][4], describing bioprocesses that are mainly composed of three major stages: Biomass pretreatment, cellulose hydrolysis, and sugars fermentation. Acid prehydrolysis at high temperature (around 200 • C) is one of the most efficient pretreatments to remove hemicelluloses and extracts present in lignocellulose materials, obtaining a cellulose and lignin-rich pretreated solid [5,6].…”

Section: Introductionmentioning

confidence: 99%

Acid and Enzymatic Fractionation of Olive Stones for Ethanol Production Using Pachysolen tannophilus

et al. 2020

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Olive stones are an abundant lignocellulose material in the countries of the Mediterranean basin that could be transformed to bioethanol by biochemical pathways. In this work, olive stones were subjected to fractionation by means of a high-temperature dilute-acid pretreatment followed by enzymatic hydrolysis of the pretreated solids. The hydrolysates obtained in these steps were separately subjected to fermentation with the yeast Pachysolen tannophilus ATCC 32691. Response surface methodology with two independent variables (temperature and reaction time) was applied for optimizing D-xylose production from the raw material by dilute acid pretreatment with 0.01 M sulfuric acid. The highest D-xylose yield in the liquid fraction was obtained in the pretreatment at 201 °C for 5.2 min. The inclusion of a detoxification step of the acid prehydrolysate, by vacuum distillation, allowed the fermentation of the sugars into ethanol and xylitol. The enzymatic hydrolysis of the pretreated solids was solely effective when using high enzyme loadings, thus leading to easily fermentable hydrolysates into ethanol. The mass macroscopic balances of the overall process illustrated that the amount of inoculum used in the fermentation of the acid prehydrolysates strongly affected the ethanol and xylitol yields.

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Recent developments in pretreatment technologies on lignocellulosic biomass: Effect of key parameters, technological improvements, and challenges

Cited by 531 publications

References 139 publications

Engineering Robust Cellulases for Tailored Lignocellulosic Degradation Cocktails

Engineering Robust Cellulases for Tailored Lignocellulosic Degradation Cocktails

Alkaline organosolv pretreatment of different sorghum stem parts for enhancing the total reducing sugar yields and p-coumaric acid release

Acid and Enzymatic Fractionation of Olive Stones for Ethanol Production Using Pachysolen tannophilus

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