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Lignocellulosic enzymatic hydrolysis

Walter Den, Virender K Sharma, Mengshan Lee, Govind Nadadur, Rajender S Varma
Anthropogenic climate change, principally induced by the large volume of carbon dioxide emission from the global economy driven by fossil fuels, has been observed and scientifically proven as a major threat to civilization. Meanwhile, fossil fuel depletion has been identified as a future challenge. Lignocellulosic biomass in the form of organic residues appears to be the most promising option as renewable feedstock for the generation of energy and platform chemicals. As of today, relatively little bioenergy comes from lignocellulosic biomass as compared to feedstock such as starch and sugarcane, primarily due to high cost of production involving pretreatment steps required to fragment biomass components via disruption of the natural recalcitrant structure of these rigid polymers; low efficiency of enzymatic hydrolysis of refractory feedstock presents a major challenge...
2018: Frontiers in Chemistry
Angela Boyce, Gary Walsh
A locally isolated strain of Aspergillus niger van Tieghem was found to produce thermostable β-xylosidase activity. The enzyme was purified by cation and anion exchange and hydrophobic interaction chromatography. Maximum activity was observed at 70-75 °C and pH 4.5. The enzyme was found to be thermostable retaining 91 and 87% of its original activity after incubation for 72 h at 60 and 65 °C, respectively, with 52% residual activity detected after 18 h at 70 °C. Available data indicates that the purified β-xylosidase is more thermostable over industrially relevant prolonged periods at high temperature than those reported from other A...
May 5, 2018: Applied Biochemistry and Biotechnology
Anthi Karnaouri, Evangelos Topakas, Leonidas Matsakas, Ulrika Rova, Paul Christakopoulos
Non-digestible oligosaccharides (NDOs) are likely prebiotic candidates that have been related to the prevention of intestinal infections and other disorders for both humans and animals. Lignocellulosic biomass is the largest carbon source in the biosphere, therefore cello-oligosacharides (COS), especially cellobiose, are potentially the most widely available choice of NDOs. Production of COS and cellobiose with enzymes offers numerous benefits over acid-catalyzed processes, as it is milder, environmentally friendly and produces fewer by-products...
2018: Frontiers in Chemistry
Andreza A Longati, Anderson R A Lino, Roberto C Giordano, Felipe F Furlan, Antonio J G Cruz
A new approach is reported for techno-economic analysis of lignocellulosic ethanol production. With this methodology, general targets for key process variables can be draw, a valuable feedback for Research & Development teams. An integrated first- and second-generation ethanol from sugarcane biorefinery is presented as a case study for the methodology, with the biomass pretreated by liquid hot water, followed by enzymatic hydrolysis of the cellulose fraction. The hemicellulose fraction may be either fermented or biodigested...
April 26, 2018: Bioresource Technology
Jing Li, Suan Shi, Maobing Tu, Brain Via, Fubao Fuelbio Sun, Sushil Adhikari
Bioconversion of lignocellulose to biofuels suffers from the degradation compounds formed during pretreatment and acid hydrolysis. In order to achieve an efficient biomass to biofuel conversion, detoxification is often required before enzymatic hydrolysis and microbial fermentation. Prehydrolysates from ethanol organosolv-pretreated pine wood were used as substrates in butanol fermentation in this study. Six detoxification approaches were studied and compared, including overliming, anion exchange resin, nonionic resin, laccase, activated carbon, and cysteine...
May 2, 2018: Applied Biochemistry and Biotechnology
Lei Qin, Xiong Zhao, Wen-Chao Li, Jia-Qing Zhu, Li Liu, Bing-Zhi Li, Ying-Jin Yuan
Background: Improving ethanol concentration and reducing enzyme dosage are main challenges in bioethanol refinery from lignocellulosic biomass. Ethylenediamine (EDA) pretreatment is a novel method to improve enzymatic digestibility of lignocellulose. In this study, simultaneous saccharification and co-fermentation (SSCF) process using EDA-pretreated corn stover was analyzed and optimized to verify the constraint factors on ethanol production. Results: Highest ethanol concentration was achieved with the following optimized SSCF conditions at 6% glucan loading: 12-h pre-hydrolysis, 34 °C, pH 5...
2018: Biotechnology for Biofuels
A Alhammad, P Adewale, M Kuttiraja, L P Christopher
Addition of surfactants to enzymatic hydrolysis has been reported to enhance the hydrolytic potential of enzymes in the bioconversion of lignocellulosic biomass to fermentable sugars. The objective of this investigation was to evaluate the effects of four non-ionic surfactants (PEG4000, PEG8000, TitronX-100, and Tween80) on the efficiency of enzymatic hydrolysis of steam-pretreated poplar using a commercial cellulase preparation (Cellic® CTec2). Statistical discriminant analysis at four variable factors (surfactant type, surfactant concentration, hydrolysis time, and substrate consistency) revealed that enzymatic hydrolysis was significantly enhanced in the presence of PEG4000, with 19...
April 26, 2018: Bioprocess and Biosystems Engineering
Joseana R Monte, Debora F Laurito-Friend, André Ferraz, Adriane M F Milagres
Sugarcane bagasses from three experimental sugarcane hybrids and a mill-reference sample were used to compare the efficiency and mode of action of acid and alkaline sulfite pretreatment processes. Varied chemical loads and reaction temperatures were used to prepare samples with distinguished characteristics regarding xylan and lignin removals, as well as sulfonation levels of residual lignins. The pretreatment with low sulfite loads (5%) under acidic conditions (pH 2) provided maximum glucose yield of 70% during enzymatic hydrolysis with cellulases (10 FPU/g) and β-glucosidases (20 UI/g bagasse)...
April 26, 2018: Biotechnology Progress
Yuyang Li, Jingdi Zhuo, Peng Liu, Peng Chen, Huizhen Hu, Youmei Wang, Shiguang Zhou, Yuanyuan Tu, Liangcai Peng, Yanting Wang
Miscanthus is a leading bioenergy crop and rice provides enormous biomass for biofuels. Using Calcofluor White staining, this work in situ observed an initial lignocellulose hydrolysis in two distinct Miscanthus accessions, rice cultivar (NPB), and Osfc16 mutant after mild chemical pretreatments. In comparison, the M. sin and Osfc16 respectively exhibited weak Calcofluor fluorescence compared to the M. sac and NPB during enzymatic hydrolysis, consistent with the high biomass saccharification detected in vitro...
July 15, 2018: Carbohydrate Polymers
Jian Du, Wenxia Song, Xiu Zhang, Jian Zhao, Guodong Liu, Yinbo Qu
High dosage of enzyme is required to achieve effective lignocellulose hydrolysis, especially at high-solid loadings, which is a significant barrier to large-scale bioconversion of lignocellulose. Here, we screened four chemical additives and three accessory proteins for their effects on the enzymatic hydrolysis of various lignocellulosic materials. The effects were found to be highly dependent on the composition and solid loadings of substrates. For xylan-extracted lignin-rich corncob residue, the enhancing effect of PEG 6000 was most pronounced and negligibly affected by solid content, which reduced more than half of enzyme demand at 20% dry matter (DM)...
April 23, 2018: Bioprocess and Biosystems Engineering
Nopparat Suriyachai, Verawat Champreda, Natthakorn Kraikul, Wikanda Techanan, Navadol Laosiripojana
A one-step formic acid-catalyzed organosolv process using a low-boiling point acid-solvent system was studied for fractionation of sugarcane bagasse. Compared to H2 SO4 , the use of formic acid as a promoter resulted in higher efficiency and selectivity on removals of hemicellulose and lignin with increased enzymatic digestibility of the cellulose-enriched solid fraction. The optimal condition from central composite design analysis was determined as 40 min residence time at 159 °C using water/ethanol/ethyl acetate/formic acid in the respective ratios of 43:20:16:21%v/v...
May 2018: 3 Biotech
Shihui Yang, Mary Ann Franden, Qing Yang, Yat-Chen Chou, Min Zhang, Philip T Pienkos
The aim of this work was to identify inhibitors in pretreated lignocellulosic slurries, evaluate high-throughput screening strategies, and investigate the impact of inhibitors on potential hydrocarbon-producing microorganisms. Compounds present in slurries that could inhibit microbial growth were identified through a detailed analysis of saccharified slurries by applying a combination of approaches of high-performance liquid chromatography, GC-MS, LC-DAD-MS, and ICP-MS. Several high-throughput assays were then evaluated to generate toxicity profiles...
2018: Frontiers in Bioengineering and Biotechnology
Peyman Mahmoodi, Keikhosro Karimi, Mohammad J Taherzadeh
Organic fraction of municipal solid waste (OFMSW) is dominated by carbohydrates, including starch-based and lignocellulosic materials. The OFMSW was hydrothermally pretreated at 100-160 °C for 0-60 min, and then assessed for enzymatic ethanol production, followed by biogas production from the stillage. The highest glucose yield of 520 g/Kg of dry OFMSW, corresponding to 131% increase compared to that of the untreated OFMSW, was obtained after the pretreatment and enzymatic hydrolysis. Through ethanolic fermentation by an inhibitory tolerant fungus, Mucor indicus, 191...
April 6, 2018: Bioresource Technology
Tian Li, Nan Liu, Xianjin Ou, Xuebing Zhao, Feng Qi, Jianzhong Huang, Dehua Liu
Background: Cellulose accessibility to cellulases (CAC) is a direct factor determining the enzymatic digestibility of lignocellulosic cellulose. Improving CAC by pretreatment is a prerequisite step for the efficient release of fermentable sugars from biomass cell wall. However, conventional methods to study the porosimetry of solid materials showed some limitations to be used for investigating CAC. In this work, an updated novel fusion protein comprising a fungal cellulose-binding module (CBM) from Cel7A cellobiohydrolase I (CBH I) of Trichoderma reesei QM6 and a di-green fluorescent protein (GFP2 ) was constructed for quantitative determination of CAC...
2018: Biotechnology for Biofuels
Ao-Lin Li, Xue-Dan Hou, Kai-Peng Lin, Xuan Zhang, Ming-Hui Fu
Lignocellulosic biomass pretreatment with deep eutectic solvents (DESs) is a promising and challenging process for production of biofuels and valuable platform chemicals. In this work, rice straw was mainly fractionated into carbohydrate-rich materials (CRMs) and lignin-rich materials (LRMs) by 90% lactic acid/choline chloride (LC)-water solution with different molar ratio of hydrogen bond donor (HBD, lactic acid) and hydrogen bond acceptor (HBA, choline chloride). It was found that high HBD/HBA molar ratio of DESs was favorable for achieving CRMs and LRMs with high purity, and both HBD and HBA were responsible for effective biomass fractionation possibly due to their synergistic effect on highly efficient breakage of the linkage between hemicellulose and lignin and thus lignin extraction...
April 12, 2018: Journal of Bioscience and Bioengineering
Paavo A Penttilä, Tomoya Imai, Jarl Hemming, Stefan Willför, Junji Sugiyama
The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose...
June 15, 2018: Carbohydrate Polymers
Jing Gao, Caiju Zheng, Tingru Tan, Shucheng Liu, Hongwu Ji
Energy efficiency ratio is significant in completely estimating lignocellulosic biomass pretreatment. In this work, rice straw (RS) was pretreated by ultra-high pressure (UHP), ionic liquid microemulsion (ILM), and a combination of UHP and ILM (ILM + UHP) at mild temperature. The chemical composition, crystalline structure, surface morphology, and enzymatic hydrolysis of untreated and pretreated RS samples were compared. After ILM pretreatment ([Emim]Ac/cyclohexane/Triton X-100/ n -butanol = 0.25/0...
April 2018: 3 Biotech
Silvana Rissi, Roselei Claudete Fontana, Mateus Arduvino Reck, Rosa Mara Borges da Silveira, Aldo José Pinheiro Dillon, Marli Camassola
The potential to produce ethanol and xylitol from xylose by the macro basidiomycete Trametes membranacea was evaluated. All strains studied showed ethanol and xylitol production. The highest ethanol production of xylose was obtained by T. membranacea strain TM158/10 with 5.65 ± 0.21 g/L at pH 4 and 28 °C with 288 h of fermentation and 5.59 ± 0.05 g/L ethanol concentration at pH 5 and 24 °C with 360 h of fermentation. When the conversion was carried out using sugars generated from enzymatic hydrolysis of sugarcane bagasse, there were higher yields from 74 to 15% for ethanol and xylitol, respectively...
April 3, 2018: Bioprocess and Biosystems Engineering
Rafael da Gama Ferreira, Adriano Rodrigues Azzoni, Sindelia Freitas
Background: The enzymatic conversion of lignocellulosic biomass into fermentable sugars is a promising approach for producing renewable fuels and chemicals. However, the cost and efficiency of the fungal enzyme cocktails that are normally employed in these processes remain a significant bottleneck. A potential route to increase hydrolysis yields and thereby reduce the hydrolysis costs would be to supplement the fungal enzymes with their lacking enzymatic activities, such as β-glucosidase...
2018: Biotechnology for Biofuels
Cynthia Sanhueza, Gonzalo Carvajal, Javiera Soto-Aguilar, Maria Elena Lienqueo, Oriana Salazar
Hydrolysis of lignocellulosic biomass depends on the concerted actions of cellulases and accessory proteins. In this work we examined the combined action of two auxiliary proteins from the brown rot fungus Gloeophyllum trabeum: a family AA9 lytic polysaccharide monooxygenase (GtLPMO) and a GH10 xylanase (GtXyn10A). The enzymes were produced in the heterologous host Pichia pastoris. In the presence of an electron source, GtLPMO increased the activity of a commercial cellulase on filter paper, and the xylanase activity of GtXyn10A on beechwood xylan...
June 2018: Enzyme and Microbial Technology
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