Search

Lignin has been recognized as a major factor contributing to lignocellulosic recalcitrance in biofuel production and attracted attentions as a high-value product in the biorefinery field. As the traditional wet chemical methods for detecting lignin content are labor-intensive, time-consuming and environment-toxic, it is an urgent need to develop high-throughput and environment-friendly techniques for large-scale crop germplasms screening. In this study, we conducted a Fourier transform infrared (FTIR) assay on 150 maize germplasms with a diverse lignin composition to build predictive models for lignin content in maize stalk. Principal component analysis (PCA) was applied to the FTIR spectra for use as model inputs. Classification and advanced gradient boosting machine (GBM) algorithms demonstrated higher predictive accuracy (0.82-0.96) compared to traditional linear and regularization algorithms (0.03-0.04) in the training set. Notably, two optimal models, built using the extreme gradient boosting (XGBoost) and light gradient boosting machine (LightGBM) algorithms, achieved R 2 values of over 0.91 in the training set and over 0.82 in the test set. Overall, the combination of FTIR and machine learning (ML) algorithms offers a high-throughput and efficient method for predicting lignin content. This approach holds significant potential for genetic breeding and the effective utilization of maize in industrial production., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The cost of enzymolysis is a major bottleneck for the industrialisation of lignocellulosic enzymatic hydrolysis technology, and recycling cellulase can reduce this cost. Herein, a sulfobetaine prepolymer (CPS) with terminal chlorine was grafted onto enzymatic hydrolysis residual lignin (EHL) from corncob to construct thermosensitive lignin-based "molecular glues" (lignin-based sulfobetaine polymers, L-CPS) that were used to recover and recycle cellulase. L-CPS 2 (1.0 g/L) was added to the corncob residue (CCR) enzymolysis system (50 °C, pH 4.5). After hydrolysis, L-CPS 2 co-precipitated with cellulase through hydrophobic binding when cooling to 25 °C. This co-precipitation decreased the amount of cellulase by 40 %. In summary, a thermally responsive lignin-based molecular glue was constructed for green recycling of cellulase, providing a new approach to decreasing the cost of lignocellulosic enzymolysis and high value utilisation of industrial lignin., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that oxidatively cleave recalcitrant polysaccharides such as cellulose. Several studies have reported LPMO action in synergy with other carbohydrate-active enzymes (CAZymes) for the degradation of lignocellulosic biomass but direct LPMO action at the plant tissue level remains challenging to investigate. Here, we have developed a MALDI-MS imaging workflow to detect oxidised oligosaccharides released by a cellulose-active LPMO at cellular level on maize tissues. Using this workflow, we imaged LPMO action and gained insight into the spatial variation and relative abundance of oxidised and non-oxidised oligosaccharides. We reveal a targeted action of the LPMO related to the composition and organisation of plant cell walls., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Xylose plants (produce xylose from corncob through dilute acid treatment) generate a large amount of corncob residue (CCR), most of which are burned and lacked of valorization. Herein, to address this issue, CCR was directly used as starting material for high-solid loading enzymatic hydrolysis via a simple strategy by combining PFI homogenization (for sufficient mixing) with batch-feeding. A maximum glucose concentration of 187.1 g/L was achieved after the saccharification with a solid loading of 25 wt% and enzyme dosage of 10 FPU/g-CCR. Furthermore, the residue of enzymatic hydrolysis (REH) was directly used as a bio-adhesive for plywood production with both high dry (1.7 MPa) and wet (1.1 MPa) surface bonding strength (higher than the standard (0.7 MPa)), and the excellent adhesion was due to the interfacial crosslinking between the REH adhesive (containing lignin, free glucose, and nanosized fibers) and cell wall of woods. Compared with traditional reported adhesives, the REH bio-adhesive has advantages of formaldehyde-free, good moisture resistance, green process, relatively low cost and easy realization. This study presents a simple and effective strategy for better utilization of CCR, which also provides beneficial reference for the valorization of other kinds of lignocellulosic biomass., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The traditional lignocellulose pretreatment by deep eutectic solvent (DES) was usually conducted under higher acidic, alkaline and high temperature conditions, which leads to the severe degradation of xylan, decreasing the subsequent reducing sugar concentration by enzymatic hydrolysis and further ethanol fermentation. It is essential to develop an effective DES that selectively removes lignin while preventing excessive xylan degradation during lignocellulose pretreatment. An effective ethylene glycol-assisted ternary DES was designed to treat corn straw (CS) at 100 °C for 6 h. 65.51 % lignin removal was achieved, over 93.46 % cellulose and 50.22 % xylan were retained in pretreated CS with excellent enzymatic digestibility (glucan conversion of 77.05 % and xylan conversion of 71.72 %), total sugar conversion could reach 75.93 %, implying the unique capacity to selectively remove lignin while preserving carbohydrate components. Furthermore, the universality of the selective removal of lignin and effective retention of xylan by ternary DES has been successfully proven by other polyols. The enzymatic hydrolysate of ternary DES-pretreated CS fermented over our genetically engineered yeast strain SFA1 OE gave a high ethanol yield of 0.488 g/g total reducing sugar, demonstrating the effectiveness of the polyol-assisted ternary DES pretreatment in achieving high-efficiency cellulosic ethanol production., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Depolymerization of the cellulose part in lignocellulose to glucose is a significant step for lignocellulose valorization. As one of the main by-products of agricultural biomass in crop-producing filed, valorization of corn straw has attracted considerable attention. In this study, a two-step depolymerizing strategy of high-pressure CO 2 -H 2 O pretreatment and oxidation-hydrolysis was applied for selective depolymerization of the cellulose component of corn straw to glucose production. Most part of the hemicellulose component could be removed through high-pressure CO 2 -H 2 O pretreatment in the presence of low concentration of acetic acid, and then as high as 32.2 % yield of glucose was achieved in water at 170 °C for 6 h without additional catalyst. The active acid sites generated during the partial oxidation of hydroxymethyl groups to carboxyl groups on glucose units of cellulose was shown to be crucial for the efficient valorization of corn straw for glucose production., (© 2024 Wiley-VCH GmbH.)

Biomass-based hydrogels have become a research hotspot because of their better biocompatibility. However, the preparation of biomass hydrogels is complicated, and they often need to be modified by introducing other substances. In this study, corncob pretreated with bisulfite (125-185 °C) was used as a raw material to prepare lignocellulose hydrogels. The results showed that directly using the pretreated sample without the washing step lowered the total hydrogel costs while preserving the lignosulfonate (LS) produced during pretreatment. The best tensile (54.1 kPa) and compressive (177.7 kPa) stresses were obtained for the hydrogel prepared from non-detoxified pretreated corncob at 165 °C (NCH-165). The sulfonic acid groups in LS could enhance the interaction between plant cellulose, thus improving its mechanical properties. The capacitor assembled from NCH-165 achieved an energy density of 236.1 Wh/kg at a power density of 499.7 W/kg and a high coulombic efficiency of more than 99 % after 2000 charge/discharge cycles. In conclusion, the present study simplifies the pathway for the preparation of flexible, conductive, and anti-freezing hydrogels by directly utilizing a non-detoxified bisulfite-pretreated corncob., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Soil salinity poses a substantial threat to agricultural productivity, resulting in far-reaching consequences. Green-synthesized lignin nanoparticles (LNPs) have emerged as significant biopolymers which effectively promote sustainable crop production and enhance abiotic stress tolerance. However, the defensive role and underlying mechanisms of LNPs against salt stress in Zea mays remain unexplored. The present study aims to elucidate two aspects: firstly, the synthesis of lignin nanoparticles from alkali lignin, which were characterized using Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Fourier Infrared Spectroscopy (FT-IR) and Energy Dispersive X-Ray Spectroscopy (EDX). The results confirmed the purity and morphology of LNPs. Secondly, the utilization of LNPs (200 mg/L) in nano priming to alleviate the adverse effects of NaCl (150 mM) on Zea mays seedlings. LNPs significantly reduced the accumulation of Na + (17/21%) and MDA levels (21/28%) in shoots/roots while increased lignin absorption (30/31%), resulting in improved photosynthetic performance and plant growth. Moreover, LNPs substantially improved plant biomass, antioxidant enzymatic activities and upregulated the expression of salt-tolerant genes (ZmNHX3 (1.52 & 2.81 FC), CBL (2.83 & 3.28 FC), ZmHKT1 (2.09 & 4.87 FC) and MAPK1 (3.50 & 2.39 FC) in both shoot and root tissues. Additionally, SEM and TEM observations of plant tissues confirmed the pivotal role of LNPs in mitigating NaCl-induced stress by reducing damages to guard cells, stomata and ultra-cellular structures. Overall, our findings highlight the efficacy of LNPs as a practical and cost-effective approach to alleviate NaCl-induced stress in Zea mays plants. These results offer a sustainable agri-environmental strategy for mitigating salt toxicity and enhancing crop production in saline environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The impact of Fenton-ultrasound treatment on the production of polyphenols and humic acid (HA) during corn stalk composting was investigated by analyzing the potential for microbial assimilation of polysaccharides in corn stalks to generate polyphenols using a 13 C-glucose tracer. The results showed that Fenton-ultrasound treatment promoted the decomposition of lignocellulose and increased the HA content, degree of polymerization (DP), and humification index (HI). The primary factor could be attributed to Fenton-ultrasound treatment-induced enhanced the abundance of lignocellulose-degrading microorganisms, as Firmicutes, Actinobacteria phylum and Aspergillis genus, which serve as the primary driving forces behind polyphenol and HA formation. Additionally, the utilization of a 13 C isotope tracer revealed that corn stalk polysaccharide decomposition products can be assimilated by microbes and subsequently secrete polyphenolic compounds. This study highlights the potential of microbial activity to generate phenolic compounds, offering a theoretical basis for increasing polyphenol production and promoting HA formation during composting., Competing Interests: Declaration of competing interest The authors state that they do not have any financial interests or personal relationships that could be perceived as potentially influencing the research reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Glycosylation, a general post-translational modification for fungal cellulase, has been shown to affect cellulase binding to its substrate. However, the exact impact of glycosylation on cellulase-lignin interaction remain unclear. Here, we demonstrated that the lignin isolated from tetrahydrofuran-pretreated corn stover exhibits strong adsorption capability to cellulase due to its negatively charged and porous structure. For the cellulases with varying glycosylation levels, the less-glycosylated protein showed high adsorption capability to lignin, and that trend was observed for the main cellulase components secreted by Penicillium oxilicum, including endoglucanase PoCel5B, cellobiohydrolase PoCel7A-2, and β-glucosidase PoBgl1. Additionally, N-glycan sites and motifs were examined using mass spectrometry, and protein structures with N-glycans were constructed, where PoBgl1 and PoCel7A-2 contained 13 and 1 glycosylated sites respectively. The results of molecular dynamics simulations indicated that the N-glycans impacted on the solvent-accessible surface area and secondary structure of protein, and the binding conformation of lignin fragment on cellulase, resulting in a decrease in binding energy (14 kcal/mol for PoBgl1 and 13 kcal/mol for PoCel7A-2), particularly for van der Waals and electrostatic interaction. Those findings suggested that glycosylation negatively impacted the lignin-cellulase interaction, providing a theoretical basis for the rational engineering of enzymes to reduce lignin-enzyme interaction., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, a surfactant-assisted diluted ethylenediamine (EDA) fractionation process was investigated for co-generation of technical lignin and biobutanol from corn stover. The results showed that the addition of PEG 8000 significantly enhanced cellulose recovery (88.9 %) and lignin removal (68.9 %) in the solid fraction. Moreover, the pulp achieved 86.5 % glucose yield and 82.6 % xylose yield in enzymatic hydrolysis. Structural characterization confirmed that the fractionation process promoted the preservation of active β-O-4 bonds (35.8/100R) in isolated lignin and functionalized the lignin through structural modification using EDA and surfactant grafting. The enzymatic hydrolysate of the pulps yielded a sugar solution for acetone-butanol-ethanol (ABE) fermentation, resulting in an ABE concentration of 15.4 g/L and an overall yield of 137.2 g/Kg of dried corn stalk. Thus, the surfactant-assisted diluted EDA fractionation has the potential to enhance the overall economic feasibility of second-generation biofuels production within the framework of biorefinery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Since the environmentally friendly reuse of corn stalks attracts more and more attention, it is an efficient and feasible way to reuse corn stalks as forage. However, whether the cellulose, lignin, and hemicellulose within corn stalks can be effectively decomposed becomes a key to reusing corn stalks as forage. Orthogonal test was designed by five different degradation temperatures (22°C, 24°C, 26°C, 28°C, 30°C), five different pH values (4, 5, 6, 8, 10), and five different degradation time durations (5, 15, 25, 30, and 35 days) to examine 25 kinds of different degradation conditions. It was found that the decomposition effect of hemicellulose, cellulose, and lignin, of group 25 (26°C, pH = 5, 25 days) was stronger compared with other groups, with the contents calculated as 8.22%, 31.55%, and 22.55% individually ( p  < 0.01, p  < 0.05). Group 19 (22°C, pH = 4, 5 days) revealed the worst degradation effect of cellulose, lignin, and hemicellulose compared to other groups, with contents calculated as 15.48%, 38.85%, and 29.57%, individually ( p  < 0.01, p  < 0.05). The research data deliver a basis for ideal degradation conditions for corn stalks degradation in combination with the digestive enzymes of P. chrysosporium and O. furnacalis larva. Aiming to explore a highly efficient and environmentally friendly corn stalk degradation method., Competing Interests: Declaration of conflicting interestsThe author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The enzymatic hydrolysis cost of lignocellulose can be reduced by improving enzymatic hydrolysis and recycling cellulase by adding additives. A series of copolymers P(SSS-co-SPE) (PSSPs) were synthesized using sodium p-styrene sulfonate (SSS) and sulfobetaine (SPE) as monomers. PSSP exhibited upper critical solution temperature response. PSSP with high molar ratio of SSS displayed more significant improved hydrolysis performance. When 10.0 g/L PSSP 5 was added to the hydrolysis system of corncob residues, and substrate enzymatic digestibility at 72 h (SED@72 h) increased by 1.4 times. PSSP with high molecular weight and moderate molar ratio of SSS, had significant temperature response, enhanced hydrolysis, and recovering cellulase properties. For high-solids hydrolysis of corncob residues, SED@48 h increased by 1.2 times with adding 4.0 g/L of PSSP 3 . Meanwhile, 50% of cellulase amount was saved at the room temperature. This work provides a new idea for reducing the hydrolysis cost of lignocellulose-based sugar platform technology., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The fermented corn stover residues are abundant renewable lignin-rich bioresources that show great potential to produce aromatic phenols. However, selective catalytic hydrogenolysis of this residual material still remains challenge to obtain high yields. Herein, a novel strategy to produce monophenolic compounds from the fermented stover over a commercial Pd/C catalyst was proposed. Taking the reaction temperature as the key variable, the highest monomer yield was 28.5 wt% at 220 °C in compaction with that of the pristine corn stover (22.8 wt%). The enhanced monophenol yield was due to the higher contents of lignin and less recalcitrance in the fermented stover. Moreover, the van Krevelen diagram revealed a slight selective CO bond scission of lignin macromolecular during fermentation as well as the dehydration and deoxygenation in hydrogenolysis reaction. Overall, this work opens a new avenue for the valorization of lignin through reductive catalytic fractionation of agricultural wastes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The industrial lignin has shown great potential to replace some of petrochemical. But the deep color of lignin limits their application in high-value field. The extraction of light-colored lignin from lignocellulose still remains challenging. Here, we reported a strategy for rapid extraction of lignin from corn stover by using a new ternary deep eutectic solvent (TDES) composed of choline chloride (ChCl), formic acid (FA) and maleic acid (MA). The color feature and structural characterization of obtained lignin was comprehensively elucidated. The results revealed that the lignin streams had light color (brightness ISO 23.44 %) with a high yield (76.3 %), purity (93.5 %), low molecular weight (Mw 1544-2040 g/mol), and low polydispersity (PDI ≤ 1.76). The introduction of MA could reduce the destruction of lignin substructure during the treatment process and avoid the deepening of lignin color. Quantitative analysis of conjugated carbonyl and quinone carbonyl and semi-quantitative analysis of lignin by 2D NMR showed that temperature had a great influence on its structure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

In this study, the hydrothermal and photocatalytic synergistic pretreatment for improving the full component utilization of corn stalk based on lignin first biorefining was employed to generate carbohydrates and obtain modified lignin. The results showed that the highest lignin removal ratio (40.70 %) and cellulose retention ratio (92.64 %) were obtained due to the smallest energy gap (6.05 eV) and the largest penetration distance (1.73 Å) between GVL and the lignin. And the yield of carbohydrates increased from 1.95 % to 58.17 % after hydrothermal pretreatment at 180 ℃. Furthermore, the modified lignin enhanced the flocculation effect, resulting in the increase of the removal of safranine-T by 6 times. In addition, the chemical and physical properties of modified lignin were studied and the mechanism of photocatalysis modification was explored. The research provides a new pretreatment method for the utilization of biomass and simultaneously achieves carbohydrate enrichment in bio-oil and purification of dye wastewater., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

It is still a challenge to find an effective solvent system that can simultaneously dissolve the cellulose and lignin in biomass residues to fabricate lignocellulose hydrogels (LHs). Herein, corncob residues from furfural production were pretreated with alkaline peroxide to regulate the lignin content. The lignin/cellulose composites with various lignin content were then dissolved and regenerated by a green and facile ZnCl 2 /CaCl 2 solvent system. The inorganic salt solvents were served as linkers and flexible LHs were obtained. Substrate material containing 10.75% lignin shows the best compressive stress (76.71 kPa). Inspired by its superior ionic conductivity, the hydrogels were assembled into a solid-state electrolyte for a zinc-ion hybrid supercapacitor. This research develops a feasible, simple, and low-cost route for lignin-containing hydrogel preparation and offers insights into the high-value application of agro-industrial lignocellulosic wastes., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Lignin-first biorefinery of corn stalk via ZrCl 4 /NaOH-catalyzed aerobic oxidation for phenolic carbonyls production was reported. Under the co-catalysis of ZrCl 4 and NaOH, lignin in corn stalk was oxidized into phenolic aldehydes (p-hydroxybenzaldehyde, vanillin, and syringaldehyde), ketones (p-hydroxyacetophenone, acetovanillone, and acetosyringone), acids (p-hydroxybenzoic acid and vanillic acid), and other derivatives. Reaction conditions, including time, temperature, ZrCl 4 dosage, NaOH dosage, MeCN/H 2 O ratio, and initial O 2 pressure were comprehensively screened, and the optimal lignin-derived monomer yields of 13.2 wt% was obtained. Among these aromatic compounds, phenolic aldehydes were the main products, and the overall selectivity of phenolic carbonyls was as high as 93%. Cellulose-rich residues after lignin-first oxidation were further characterized by thermogravimetry and analytical pyrolysis with corn stalk as the control, proving the good fragmentation and dissolution of lignin streams. In general, ZrCl 4 /NaOH-catalyzed lignin-first oxidation provided a novel approach for lignin valorization, and achieved the highest reported phenolic carbonyls selectivity., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This work presents a dynamic view of the enzymatic degradation of maize cell walls, and sheds new light on the recalcitrance of hot water pretreated maize stem internodes. Infra-red microspectrometry, mass spectrometry, fluorescence recovery after photobleaching and fluorescence imaging were combined to investigate enzymatic hydrolysis at the cell scale. Depending on their polymer composition and organisation, cell types exhibits different extent and rate of enzymatic degradation. Enzymes act sequentially from the cell walls rich in accessible cellulose to the most recalcitrant cells. This phenomenon can be linked to the heterogeneous distribution of enzymes in the liquid medium and the adsorption/desorption mechanisms that differ with the type of cell., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Novel Immunological and Mass Spectrometry Methods for Comprehensive Analysis of Recalcitrant Oligosaccharides in AFEX Pretreated Corn Stover. Lignocellulosic biomass is a sustainable alternative to fossil fuel and is extensively used for developing bio-based technologies to produce products such as food, feed, fuel, and chemicals. The key to these technologies is to develop cost competitive processes to convert complex carbohydrates present in plant cell wall to simple sugars such as glucose, xylose, and arabinose. Since lignocellulosic biomass is highly recalcitrant, it must undergo a combination of thermochemical treatment such as Ammonia Fiber Expansion (AFEX), dilute acid (DA), Ionic Liquid (IL) and biological treatment such as enzyme hydrolysis and microbial fermentation to produce desired products. However, when using commercial fungal enzymes during hydrolysis, only 75-85% of the soluble sugars generated are monomeric sugars, while the remaining 15-25% are soluble recalcitrant oligosaccharides that cannot be easily utilized by microorganisms. Previously, we successfully separated and purified the soluble recalcitrant oligosaccharides using a combination of charcoal and celite-based separation followed by size exclusion chromatography and studies their inhibitory properties on enzymes. We discovered that the oligosaccharides with higher degree of polymerization (DP) containing methylated uronic acid substitutions were more recalcitrant towards commercial enzyme mixtures than lower DP and neutral oligosaccharides. Here, we report the use of several complementary techniques that include glycome profiling using plant biomass glycan specific monoclonal antibodies (mAbs) to characterize sugar linkages in plant cell walls and enzymatic hydrolysate, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) using structurally-informative diagnostic peaks offered by negative ion post-secondary decay spectra, gas chromatography followed by mass spectrometry (GC-MS) to characterize oligosaccharide sugar linkages with and without derivatization. Since oligosaccharides (DP 4-20) are small, it is challenging to mobilize these molecules for mAbs binding and characterization. To overcome this problem, we have applied a new biotin-coupling based oligosaccharide immobilization method that successfully tagged most of the low DP soluble oligosaccharides on to a micro-plate surface followed by specific linkage analysis using mAbs in a high-throughput system. This new approach will help develop more advanced versions of future high throughput glycome profiling methods that can be used to separate and characterize oligosaccharides present in biomarkers for diagnostic applications., (© 2022. The Author(s).)

This study investigates digestibility enhancements of lignocellulose from shock pretreatment, alkaline pretreatment, and combination. Shock pretreatment subjects aqueous slurries of lignocellulose to shock waves, which disrupts its structure rendering it more susceptible to hydrolysis. Alkaline pretreatment submerges the biomass in aqueous alkali (NaOH, Ca(OH) 2 ), which removes lignin and acetyl groups. As indicators of digestibility, cellulase (CTec3) and hemicellulase (HTec3) were used to saccharify the pretreated corn stover and the resulting filtrate which contains about 10% of the sugars. Shock is most effective when it precedes alkaline pretreatment, presumably because it opens the biomass structure and enhances diffusion of pretreatment chemicals. Lignocellulose digestibility from calcium hydroxide treatment improves significantly with oxygen addition. In contrast, sodium hydroxide is a more potent alkali, and thereby eliminates the need for oxygen to enhance pretreatment. At low hydroxide loadings (<4 g OH - /100 g dry biomass), both NaOH and Ca(OH) 2 provide similar increases in digestibility; however, at high hydroxide loadings, NaOH is superior. For animal feed, Ca(OH) 2 treatment is recommended, because residual calcium ions are valuable nutrients. In contrast, for methane-arrested anaerobic digestion, NaOH treatment is preferred because NaHCO 3 is a stronger buffer. At 50°C, shock pretreatment improves sugar yields at all NaOH loadings. The effect of shock is most pronounced when the no-shock control employed the same soaking-and-drying procedure as the shock treatment. The recommended conditions are shock treatment (5.52 bar [abs] initial H 2 /O 2 pressure) followed by 50°C alkaline treatment with NaOH loading of 4 g OH - /100 g dry biomass for 1 h., (© 2021 American Institute of Chemical Engineers.)

Corn dry milling provides a mature model for lignocellulose biorefinery process. To copy this technical success, a crucial step is to transform lignocellulose into starch-like carbohydrates (SLC), similar to milled corn grain and in a similar fashion to corn dry milling. The transformation process should be zero wastewater generation and sufficient fermentable sugar conservation; the product should be in solid particle form, free of toxic residues, and high enzymatic hydrolysis yield and fermentability. Here we designed and verified a SLC transformation process by (i) biodegradable oxalic acid-catalyzed pretreatment, and (ii) simultaneous biodegradation of inhibitors and oxalic acid catalyst. The oxalic acid catalyst was effective on disrupting the lignocellulose structure and also biodegradable at low pH value. The biodetoxification fungus Paecilomyces variotii FN89 was capable of degrading the furan/phenolic aldehydes and oxalic acid simultaneously and ultimately, while the fermentable sugars were well preserved. The obtained SLC from wheat straw and corn stover were similar to dry milled corn meal in terms of morphological properties, fermentable sugar contents, enzymatic hydrolysis yield, elemental contents, and free of inhibitors and acid catalyst. The bioconversion of starch-like wheat straw and corn stover produced 78.5 and 75.3 g/L of ethanol (9.9% and 9.5%, v/v) with the yield of 0.47 and 0.45 g ethanol/g cellulose/xylose, respectively, compared with 78.7 g/L (10.0%, v/v) from corn meal and the yield of 0.48 g ethanol/g starch. Mass balances suggest that the ethanol yield, wastewater generation, and elemental recycling of the SLC from lignocellulose were essentially the same as those of corn meal., (© 2021 Wiley Periodicals LLC.)

The probiotic strain of Bacillus subtilis presents a promising application potential for the value-added bio-utilization of lignocellulosic carbohydrates. By the combined acidolysis pretreatment and enzymatic hydrolysis, hemicellulose and cellulose constituents of corncob were efficiently converted respectively into fermentable C5 and C6 sugars, mainly including xylose and glucose. B. subtilis grew well in xylose solution while it was hindered completely in the acidolysis broth because of the bio-toxicity of degraded chemicals derived from corncob. A mixed-fermentation technique was therefore developed and performed to blend the acidolysis broth and enzymatic hydrolysis slurry together, by which C5 and C6 sugar molecules were successfully fermented and efficiently utilized for the growth of B. subtilis cells with a yield of 0.33 g cells/g sugar consumed. A net amount of 205.9 ± 9.0 g of B. subtilis powder was obtained from 1000 g of corncob that could improve the economic benefits of the process to around 5-7 times., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Besides the use of maize grain as food and feed, maize stover can be a profitable by-product for cellulosic ethanol production, whereas the whole plant can be used for silage production. However, yield is reduced by pest damages, stem corn borers being one of the most important yield constraints. Overall, cell wall composition is key in determining the quality of maize biomass, as well as pest resistance. This study aims to evaluate the composition of the four cell wall fractions (cellulose, hemicellulose, lignin and hydroxycinnamates) in diverse maize genotypes and to understand how this composition influences the resistance to pests, ethanol capacity and digestibility., Results: The following results can be highlighted: (i) pests' resistant materials may show cell walls with low p-coumaric acid and low hemicellulose content; (ii) inbred lines showing cell walls with high cellulose content and high diferulate cross-linking may present higher performance for ethanol production; (iii) and inbreds with enhanced digestibility may have cell walls poor in neutral detergent fibre and diferulates, combined with a lignin polymer composition richer in G subunits., Conclusions: Results evidence that there is no maize cell wall ideotype among the tested for optimal performance for various uses, and maize plants should be specifically bred for each particular application.

Mild and effective pretreatments are essential to deconstruct lignocellulosic biomass so as to reuse cellulose content for value-added products. In this study, sequential multimode-ultrasound and microwave with natural ternary deep eutectic solvent (NATDES) pretreatments were used to deconstruct corn straw and optimized factors such as NATDES, ultrasonic, and microwave parameters. Results indicated that the ultrasound-NATDES or microwave-NATDES pretreatment could remove 37.86% and 52.36% lignin, respectively. When using sequential multimode-ultrasound and microwave assisted NATDES pretreatment, the delignification efficiency increased to 61.50%, and the cellulose content increased from 34.70% to 76.08%. In addition, the delignification of sequential multimode-ultrasound and microwave assisted NATDES pretreatment (under the mild conditions of microwave heating at 60 °C and 60 min) increased to 57.39%, and the cellulose content increased to 59.98%, too. This highlighted the effect of the combined ultrasound and microwave technology. Finally, the microstructural changes of mercury intrusion porosimeters, scanning electron microscopy, thermogravimetric, X-ray diffraction and Fourier transform mid-infrared spectroscopy were conducted to confirm the effectiveness of this method to deconstruct corn straw. A mechanism of the deconstruction of corn straw biomass in NATDES with the assistance of the sequential multimode-ultrasound and microwave heating was proposed. This research could open a window for future use of biomass energy by deconstructing lignocellulosic biomasses using environmentally friendly pretreatment methods., (Copyright © 2020 The Author(s). Published by Elsevier B.V. All rights reserved.)

Pretreatment can improve the hydrolysis efficiency of cellulose, in which biological pretreatment plays an important role. In the present study, we uncovered that Rhodococcus has the ability of lignin degradation, which can decompose lignin and serve as a carbon source to meet the needs of its own growth. We used Rhodococcus to pretreat the corn stalks and evaluate the effect on cellulose hydrolysis. The concentration of reducing sugar produced by the hydrolysis of corn stalk after pretreatment of Rhodococcus is 2.95 g/L. SEM imaging showed that Rhodococcus pretreatment resulted the surface of corn stalk to be no longer complete, some lamellar structures fall off, and leave obvious traces, and obvious delamination was found at the edge of the fault. AFM imaging showed that the pretreatment changed the lignin structure of the corn stalk material surface, resulting in a higher surface roughness of 9.37. These results indicated that Rhodococcus pretreatment can improve the saccharification efficiency of cellulose by removing lignin and increasing the surface roughness of the material.

In order to minimize waste liquor, save resources, and reduce costs, the effects of alkali recycling and ozone recycling on enzymatic conversion in alkali combined with ozone pretreatment of corn stover and the mechanism were studied. The results showed that as the number of cycles of alkali/ozone filtrate increased, the enzymatic conversion and the loss of reducing sugars showed a downward trend. It was indicated that the ability of alkali to damage lignocellulosic decreased with an increasing number of alkali circulation and the accumulation of lignin degradation products generated during ozonolysis inhibited enzymatic conversion. When the ozone filtrate was recovered and used for hydrolysis directly, the enzymatic conversion rates were basically the same compared with the first self-circulation of ozone filtrate, and no sewage was discharged. In conclusion, the optimal circulating pretreatment was four times alkali circulation and ozone filtrate was used as an enzymolysis liquid directly, and the conversion rates of cellulose and hemicellulose were 85.96% and 34.26%, respectively, saving 44% alkali consumption at the same time. This paper provided the theoretical basis for the development of lignocellulose pretreatment technology with low cost, high efficiency, and high conversion rate.

In this work, deep eutectic solvent (DES) was prepared by mixing choline chloride (ChCl) with lactic acid (LA), and effects of cellulase non-productive binding onto DES-extracted lignin from willow and corn stover on enzymatic hydrolysis of cellulose was investigated. The correlation between hydrolysis yield of cellulose and chemical features of lignin was evaluated, and a potential inhibitory mechanism was proposed. Condensation of lignin was observed during DES treatment, and these condensed aromatic structures had an increased tendency to adsorb enzymes through hydrophobic interactions. As well as hydrophobic interactions mediated by lignin condensation, an increase in phenolic hydroxyl groups resulted in a greater amount of hydrogen bonds between cellulases and lignin that appeared to inhibit enzymatic hydrolysis yields of cellulose (39.96-42.86 % to 31.96-32.68 %). Although large amounts of COOHs were generated, the elevated electrostatic repulsion as a result of ionic groups was insufficient to decrease non-productive adsorption., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A new sequence of steam explosion (SE) with periodic peristalsis (PP) exploited to fractionate corn pericarp (CP), and its high solid cellulosic hydrolysis to increase sugar yield. In this investigation, the optimum SE-condition was 0.8 MPa/5 min., recovered around 12.62 % total sugars than untreated CP, whereas glucan and xylan digestibility reached around 97 % and 87 %, respectively. Besides that, the unground SECP conversion increased by 27.10 % glucan and 34.18 % xylan than the ground one. FE-SEM, FTIR, XRD results confirmed that SE significantly fractionated the amorphous substances that driven the increment of the crystallinity index. SE changed the functional groups without altering the lignin, and also the formation of degradations products was negligible and not detrimental to sugars conversion. An unpolluted SEPP enzymatic hydrolysis system at high solid loading (25 %) with compatible low cellulase dose (15 FPU g -1 solids) was beneficial to intensified sugars conversion., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2020. Published by Elsevier Ltd.)

The production of acetone-butanol-ethanol by solventogenic Clostridium using lignocellulosic biomass can be a potential alternative to petroleum-based butanol. However, previous studies on nondetoxified lignocellulose hydrolysate could not provide better results when compared to those in synthetic medium. In this study, we engineered the pentose pathway of Clostridium beijerinckii NCIMB 8052, which was then subjected to adaptive laboratory evolution in the gradient mixture of synthetic medium and pretreated corn stover enzymatic hydrolysate (CSH) prepared according to the National Renewable Energy Laboratory (NREL) standard. The final resultant strain CIBTS1274A produced 20.7 g/L of total solvents in NREL CSH diluted to 6% initial total sugars, supplemented with ammonium acetate. This performance was comparable with that of corn-based butanol. In addition, this strain was successfully used in the scale-up operation using nondetoxified corn stover and corncob hydrolysate at Lignicell Refining Biotechnologies Ltd., which once was the only commercial biobutanol industry in the world.

Agricultural wastes are an alternative to the use of wood in plastic composites, thanks to their abundance, easy availability and other environmental and economic advantages. Agricultural wastes can be processed to obtain lignocellulosic fibers of different compositions that will allow better performance of their composites and the final desired residues' valorization. In this context, the current investigation aims at the management of corn stover wastes to be applied as reinforcement of polypropylene (PP). Four types of lignocellulosic fibers were obtained by submitting the wastes to mechanical, thermomechanical, semi-chemical or chemical processes. Corn fibers were characterized in terms of chemical composition, morphology and mechanical properties. In addition, PP was reinforced with corn fibers and the composites' stiffness evaluated. An assessment of the influence of the fiber composition on the mechanical performance of the composites is conducted. It is observed the key role of lignin content on the intrinsic modulus of the reinforcing fibers, which directly affected the final stiffness of composites. The best performance was achieved for an optimal kappa number between 40 and 50, corresponding to the semi-chemical fibers. The intrinsic modulus of the fibers, as well as the efficiency factor, length and orientation factors in composites were determined via micromechanical models., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this paper, response surface methodology (RSM) designs and an artificial neural network (ANN) are used to obtain the optimal conditions for the oxy-combustion of a corn-rape blend. The ignition temperature ( T e ) and burnout index ( D f ) were selected as the responses to be optimised, while the CO 2 /O 2 molar ratio, the total flow, and the proportion of rape in the blend were chosen as the influencing factors. For the RSM designs, complete, Box-Behnken, and central composite designs were performed to assess the experimental results. By applying the RSM, it was found that the principal effects of the three factors were statistically significant to compute both responses. Only the interactions of the factors on D f were successfully described by the Box-Behnken model, while the complete design model was adequate to describe such interactions on both responses. The central composite design was found to be inadequate to describe the factor interactions. Nevertheless, the three methods predicted the optimal conditions properly, due to the cancellation of net positive and negative errors in the mathematical adjustment. The ANN presented the highest regression coefficient of all methods tested and needed only 20 experiments to reach the best predictions, compared with the 32 experiments needed by the best RSM method. Hence, the ANN was found to be the most efficient model, in terms of good prediction ability and a low resource requirement. Finally, the optimum point was found to be a CO 2 /O 2 molar ratio of 3.3, a total flow of 108 mL/min, and 61% of rape in the biomass blend., Competing Interests: The authors declare no conflict of interest.

Recently, attention has shifted to the use of mixed lignocellulosic substrates for the production of cellulolytic enzymes. However, researchers have focused mainly on achieving increased enzyme yields while neglecting other properties of the enzymes when using such mixtures. In this first-ever report of the application of Prosopis africana pod (PAP) in cellulase production, we investigated the effect of its combination with corn cob (CC), as an inducing carbon source, on the amounts and quality of crude endoglucanase produced by Bacillus thuringiensis SS12. The organism was grown on PAP, CC or their 1:1% w/w mixture (MS) and the crude endoglucanases produced were tested for activity, hydrolytic efficiency, and thermostability. PAP supported the highest enzyme activity (0.138 U/mL) and its endoglucanase was the most effective in hydrolyzing CMC and filter paper while CC-derived endoglucanase was the best for hydrolysis of alkali-pretreated CC. Enzyme activity of MS-derived endoglucanase (0.110 U/mL) was intermediate to that of PAP and CC (0.091 U/mL) and was the most stable at elevated temperatures (70 and 80 °C). It also liberated the least amount of reducing sugars from all tested substrates. Combination of both the substrates, thus, favored enzyme production and thermostability but was detrimental to hydrolytic efficiency.

To be effective, steam pretreatment is typically carried out at temperatures/pressures above the glass transition point (Tg) of biomass lignin so that it can partly fluidize and relocate. The relocation of Douglas-fir and corn stover derived lignin was compared with the expectation that, with the corn stover lignin's lower hydrophobicity and molecular weight, it would be more readily fluidized. It was apparent that the Tg of lignin decreased as the moisture increased, with the easier access of steam to the corn stover lignin promoting its plasticization. Although the softwood lignin was more recalcitrant, when it was incorporated onto filter paper, it too could be plasticized, with its relocation enhancing enzymatic hydrolysis. When lignin recondensation was minimized, the increased hydrophobicity suppressed lignin relocation. It was apparent that differences in the accessibility of the lignin present in Douglas-fir and corn stover to steam significantly impacted lignin fluidization, relocation, and subsequent cellulose hydrolysis., (© 2019 Wiley Periodicals, Inc.)

Plant biologists are seeking new approaches for modifying lignin to improve the digestion and utilization of structural polysaccharides in crop cultivars for the production of biofuels, biochemicals, and livestock. To identify promising targets for lignin bioengineering, we artificially lignified maize (Zea mays L.) cell walls with normal monolignols plus 21 structurally diverse alternative monomers to assess their suitability for lignification and for improving fiber digestibility. Lignin formation and structure were assessed by mass balance, Klason lignin, acetyl bromide lignin, gel-state 2D-NMR and thioacidolysis procedures, and digestibility was evaluated with rumen microflora and from glucose production by fungal enzymes following mild acid or base pretreatments. Highly acidic or hydrophilic monomers proved unsuitable for lignin modification because they severely depressed cell wall lignification. By contrast, monomers designed to moderately alter hydrophobicity or introduce cleavable acetal, amide, or ester functionalities into the polymer often readily formed lignin, but most failed to improve digestibility, even after chemical pretreatment. Fortunately, several types of phenylpropanoid derivatives containing multiple ester-linked catechol or pyrogallol units were identified as desirable genetic engineering targets because they readily formed wall-bound polymers and improved digestibility, presumably by blocking cross-linking of lignin to structural polysaccharides and promoting lignin fragmentation during mild acidic and especially alkaline pretreatment., (Published by Elsevier B.V.)

In the early stage, the best conditions for alkali-bound ozone pretreatment were studied. But after treatment, the alkaline black liquor was directly discarded due to the large amount of organic matter, resulting in environmental pollution and waste of resources. In this paper, the alkaline black liquor was recycled under the optimal pretreatment conditions. The results showed that the number of alkaline black liquor cycles had little effect on hemicellulose content, and had a great influence on cellulose content and lignin content. Through structural characterization of corn stover, it was found that the pretreatment caused structural changes of lignin in straw. However, when the alkaline black liquor was recycled for the fourth time, the ether bond in the side chain of lignin and the covalent bond between the components were not sufficiently destroyed, and the damage to the phenolic hydroxyl group was also weakened. It was indicated that when the alkaline black liquor was recycled for the fourth time, the destruction effect of the alkaline black liquor on the straw was significantly inhibited. Therefore, the optimal circulation time of alkaline black liquor was three times, and the cellulolytic conversion rate was 81.53%.

High cost and high viscosity of ionic liquid restricted its commercial application in pretreatment of lignocellulose. Water and ethanol were used as additive in [EMIM][OAc] to pretreat corn cob at moderate temperature (< 100 °C). It was found that enzyme hydrolysis (EH) sugar yield was increased with the increase of IL content. The largest EH sugar yield of 68.8% was obtained when pure IL was used. However, for [EMIM][OAc]/ethanol, the EH sugar yield as high as 66.9% was gained when the IL content was 80%, which was comparable to that for pure IL pretreatment. In addition, Kamlet-Taft parameter was calculated to characterize the polarity solvency of binary liquid phase, to illustrate the underlying reason for the increase of EH sugar and the lignin removal. Finally, to demonstrate the crystalline and microstructure change after pretreatment, XRD and SEM were performed for the raw materials and the pretreated samples.

Lignocellulosic biomass is regarded as an ideal renewable resource for replacing traditional fossil fuels. Corncob residues (CRs) generated after hemicelluloses pre-extraction of corncobs were potential feedstocks to produce lignin-based products. Three lignin fractions, i.e., dioxane lignin (DL), milled-wood lignin (MWL), and enzymatic mild acidolysis lignin (EMAL), were isolated from CRs and characterized by HPLC, GPC, FT-IR, NMR, and TGA to reveal characteristics of CRs lignin to better understand its potential applications. The results showed that the yield of DL, MWL and EMAL were 12.8%, 14.7% and 15.6%, respectively. The molecular weight of DL, MWL and EMAL were 2001, 5391, and 2629 g/mol, respectively. The EMAL and MWL had similar structural features including guaiacyl and syringyl units, β-O-4' aryl ether, p-coumaric acids, ferulates, and phenylcoumarans, while the structure of DL was relatively simple. It is expected that this work will provide some useful information for the utilization of CRs in view of biorefinery., (Copyright © 2019. Published by Elsevier B.V.)

Plant cell walls development is an integrated process during which several components are deposited successively. In the cell walls in grass, the accessibility of structural polysaccharides is limited by the cell walls structure and composition mainly as a result of phenolic compounds. Here, we studied the patterns of cell walls establishment in the internode supporting the ear in three distinct maize genotypes. The developmental patterns observed in the internode cell walls in terms of its composition are reported with an emphasis on lignification, p-coumaroylation and feruloylation. We combined biochemical and histological approaches and revealed that internode cell walls development in maize before flowering is characterized by the rapid deposition of secondary cell walls components and robust lignification in both the pith and the rind. After flowering and until silage maturity, the slow deposition of secondary walls components occurs in the cortical region, and the deposited lignins are rich in β-O-4 bonds and are highly p-coumaroylated. We conclude the paper by proposing a revised spatiotemporal model based on that proposed by Terashima et al. (1993) for cell walls development in grass., Competing Interests: The authors have declared that no competing interests exist.

The recalcitrance of lignocellulosic biomass is a major factor limiting its conversion into biofuels. Therefore, in this study, we pretreated corn stalk with 2% Na 2 CO 3 and 2% H 2 O 2 for time 70 min at 130°C using a corn stalk to liquid ratio of 1:10. The fermentation broth from multicopy Saccharomyces cerevisiae strains engineered for lignocellulase synthesis was used to enzymatically hydrolyze the pretreated corn stalk. The highest monosaccharide yield (102 mmol/L) was obtained using 15 IU endocellulase, 10 IU exocellulase, and 15 IU β-glucosidase per gram of cellulose and 20 IU xylanase per gram of hemicellulose. Subsequently, the high-efficiency ethanol-producing S. cerevisiae strain WXY12, which can produce ethanol from glucose and xylose simultaneously, was added to the fermentation system. The entire process involved ethanol production through simultaneous saccharification and fermentation (SSF). Optimization of the fermentation conditions (yeast powder as a nitrogen source, temperature of 30°C, MgSO 4 as a metal ion inducer, rotation speed of 180 rpm, solid-liquid ratio of 1:8, and inoculation amount of 2%) resulted in an ethanol output of 46.87 g/L and a theoretical conversion rate of 27.4%. The results of this study improved corn stalk utilization, reduced hydrolysis costs, and generated high ethanol yields., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Water-soluble carbohydrates in raw lignocellulosic biomass are converted into hydroxymethylfurfural (HMF) in the acid-based pretreatment, thus increasing the detoxification intensity and reducing the fermentation efficiency of cellulosic ethanol. Therefore, reducing water-soluble carbohydrates in raw corn stover is crucially important to reduce the inhibitors' generation and improve the ethanol fermentation efficiency. In this study, aerobic solid-state fermentation of corn stover by inoculating Aspergillus niger spores converted 83% of the endogenous water-soluble carbohydrates into citric acid, leading to the decrease of 41% of HMF generation and 8% of sulfuric acid usage during the dry acid pretreatment. The reduced inhibitor generation improved the ethanol fermentability by 11% more ethanol than that of the corn stover without water-soluble carbohydrates' removal. This suggests that the removal of the water-soluble carbohydrates before pretreatment significantly reduced the inhibitors' generation in pretreatment and improved the fermentation efficiency of cellulosic ethanol.

The hemicellulose, cellulose and lignin were directly separated from corn stalk, and their liquefaction processes were investigated via acid-catalyzed solvolysis treatment with 1,2-propylene glycol (PG) and diethylene glycol (DEG) to produce bio-oil and residues. The main components, functional groups and organics structure of bio-oil were analyzed by the FTIR, 1 H-NMR, 13 C-NMR, GCMS, and TGA. It was found that there had a similar tendency in the liquefaction processes of cellulose, hemicellulose and lignin. Corn stalk and its biomass components were degraded and formed plentiful low-molecular polymers by acid catalysis, prior to polymers were converted into corresponding PG/DEG-derivatives. Finally, low-molecular weight soluble substances and insoluble residues were generated by decomposition and polymerization. Additionally, more than 80% compounds' carbon number in four bio-oils was below 25. The residues were mostly stemmed from macromolecules produced by degradation products and PG/DEG or re-polymerization between degraded small molecules., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A lignin amphoteric surfactant and betaine could enhance the enzymatic hydrolysis of lignocellulose and recover cellulase. The effects of lignosulfonate quaternary ammonium salt (SLQA) and dodecyl dimethyl betaine (BS12) on enzymatic hydrolysis digestibility, ethanol yield, yeast cell viability, and other properties of high-solid enzymatic hydrolysis and fermentation of a corncob residue were studied in this research. The results suggested that SLQA and 1 g/L BS12 effectively improved the ethanol yield through enhancing enzymatic hydrolysis. SLQA had no significant effect on the yeast cell membrane and glucose fermentation. However, 5 g/L BS12 reduced the ethanol yield as a result of the fact that 5 g/L BS12 damaged the yeast cell membrane and inhibited the conversion of glucose to ethanol. Our research also suggested that 1 g/L BS12 enhanced the ethanol yield of corncob residue fermentation, which was attributed to the fact that lignin in the corncob adsorbed BS12 and decreased its concentration in solution to a safe level for the yeast.

Lignocellulosic biomass from corn stover holds promise as a raw material for the production of alternative energy to replace fossil fuels. In this study, structural properties of corn stover after pretreatment using mechanical pulverization with or without subsequent phosphoric acid treatment were investigated. The results showed that a pulverization step loosened the compact structure of corn stover lignocellulose and effectively reduced particle size, while both pulverization and phosphoric acid pretreatment steps altered the crystallinity index. During pretreatment, hemicellulose content was reduced and accessibility of β-1,4 glycosidic bonds to hydrolysis by cellulase increased, while almost all lignin was retained. The results showed that the combined two-step pretreatment method improved sugar yield from lignocellulose during subsequent enzymatic hydrolysis from 20.01 mg/g to 41.41 mg/g in glucose yield. These results should guide the development of methods for improved lignocellulose conversion to sugars for enhanced bioethanol production., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Funneling and functionalization of a mixture of lignin-derived monomers into a single high-value chemical is fascinating. Reported herein is a three-step strategy for the production of terephthalic acid (TPA) from lignin-derived monomer mixtures, in which redundant, non-uniform substitutes such as methoxy groups are removed and the desired carboxy groups are introduced. This strategy begins with the hydro-treatment of corn-stover-derived lignin oil over a supported molybdenum catalyst to selectively remove methoxy groups. The generated 4-alkylphenols are converted into 4-alkylbenzoic acids by carbonylation with carbon monoxide. The Co-Mn-Br catalyst then oxidizes various alkyl chains into carboxy groups, transforming the 4-alkylbenzoic acid mixture into a single product: TPA. For this route, the overall yields of TPA based on lignin content of corn stover could reach 15.5 wt %, and importantly, TPA with greater than 99 % purity was obtained simply by first decanting the reaction mixture and then washing the solid product with water., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An efficient hybrid pretreatment method was developed for butanol production from corn stover using dilute sulfuric acid (DA) and aqueous ammonia (AA). With the optimized AA concentration, treatment temperature and time of 10% AA, 80 °C and 24 h, the hybrid pretreatment could effectively dissolve hemicellulose and lignin with solid recovery rate of 37.45% and lignin reduction rate of 86.77% compared to those of 57.75% and 45.84% from single DA pretreatment. By washing 1 time after each step treatment, sugar yield and butanol production were increased to 401.76 mg/g-CS and 10.89 g/L from 346.04 mg/g-CS and 9.33 g/L obtained without washing. Compared with conventional single DA and AA pretreatment methods, wastewater generation was reduced to 0.83 L/g-butanol from 2.11 and 3.46 L/g-butanol, indicating this hybrid pretreatment could be an effective approach for improving butanol production from lignocellulosic feedstocks., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this study, the dry torrefaction (DT) and wet torrefaction (WT) were compared at different temperatures to explore the effect of these pretreatments on the characteristic of corn stalk digestate (CSD) and the thermal degradation behaviors. The results indicated the both torrefactions improved the fuel properties of CSD, including the lower volatiles content, higher carbon content and HHV. The WT showed higher removals of organics and alkali metals, while DT retained more carbon and ash. The SEM, FTIR and XRD analyses indicated the existence of organic coverings of WT samples, and showed richer surface functional groups, relative complete lignin structure and higher crystallinity compared to DT samples. The thermogravimetric analysis displayed the torrefied temperature above 260 °C (DT) or 220 °C (WT) was not suitable for CSD pyrolysis. Besides, the WT samples showed the more concentrated combustion range, while DT tends the burning of CSD to the behavior of coal., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Lignin is a complex aromatic biopolymer that strengthens and waterproofs plant secondary cell walls, enabling mechanical stability in trees and long-distance water transport in xylem. Lignin removal is a key step in paper production and biomass conversion to biofuels, motivating efforts to re-engineer lignin biosynthesis. However, the physical nature of lignin's interactions with wall polysaccharides is not well understood. Here we show that lignin self-aggregates to form highly hydrophobic and dynamically unique nanodomains, with extensive surface contacts to xylan. Solid-state NMR spectroscopy of intact maize stems, supported by dynamic nuclear polarization, reveals that lignin has abundant electrostatic interactions with the polar motifs of xylan. Lignin preferentially binds xylans with 3-fold or distorted 2-fold helical screw conformations, indicative of xylans not closely associated with cellulose. These findings advance our knowledge of the molecular-level organization of lignocellulosic biomass, providing the structural foundation for optimization of post-harvest processing for biofuels and biomaterials.

Two-stage dilute hydrochloric acid (DA)/aqueous ammonia wet oxidation (AWO) pretreatment was used to recover the sugars of corn stover. The morphology characterizations of samples were detected by SEM, BET and SXT. The results showed that DA-AWO process demonstrated a positive effect on sugar recovery compared to AWO-DA. 82.8% of xylan was recovered in the first stage of DA-AWO process at 120 °C for 40 min with 1 wt% HCl. The second stage was performed under relative mild reaction conditions (130 °C, 12.6 wt% ammonium hydroxide, 3.0 MPa O 2 , 40 min), and 86.1% lignin could be removed. 71.5% of glucan was achieved with a low enzyme dosage (3 FPU·g -1 ) in the following enzymatic hydrolysis. DA-AWO pretreatment was effective due to its sufficient hydrolysis of hemicellulose in the first stage and remarkably removal of the lignin in the second stage, resulting in high sugar recovery with a low enzyme dosage., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Fast pyrolysis of agricultural straw residues based on ceramic ball circulation heating was studied by using an originally developed V-shaped drop tube pyrolysis unit. The yields of bio-oil, bio-char and pyrolysis gas from these straw residues were in the range of 41-46, 26-30 and 26-29 wt%, respectively, with maize straw giving the highest bio-oil yield. A quadratic model was developed to correlate the cellulose-to-lignin-ratio (CLR) and hemicellulose-to-lignin-ratio (HLR) with bio-oil yield. For a given HLR above 1.12, the bio-oil yield continued to increase as the CLR increased. However, when the HLR was between 0.86 and 1.12, it tended to decrease first and then increase with the increase of CLR. In contrast with CS, the proportions of acids and ketones in the bio-oils increased by 13.3% and 14.8% for MS and 9.2% and 30.5% for WS, respectively, while the proportion of phenols decreased by 9.9% and 14.3%., (Copyright © 2018 Elsevier Ltd. All rights reserved.)