Effect of sequential acid-alkaline treatment on physical and chemical characteristics of lignin and cellulose from pine (Pinus spp.) residual sawdust

Computer-assisted enzyme cocktails enhance fermentation by overcoming toxic inhibitors from pretreatment processes

Lignocellulosic biomass is the most abundant form of biomass available for fuel production, serving as the fourth leading energy source globally. However, inhibitors generated during pretreatment processes often hinder fermentation performance and conversion efficiency. In this study, we developed an enhanced computer-assisted enzyme cocktail strategy (ComEC 2.0) to mitigate the inhibitory effects. Through experimental studies and molecular dynamics simulations, eight optimization strategies were developed for enzyme cocktail formulation (comprising CBHI, EG, BG, XYN, LPMO). Notably, Strategy 4b, which accounts for both overall hydration and the synergistic effects between LPMO and CBHI/EG/BG/XYN, increased glucose and xylose yields by 20.7 % and 21 %, respectively, using corn stover, reducing Process Mass Intensity (PMI) by 70.78 % and water use by 80 % during ethanol fermentation. Applying Strategy 4b to industrial corn cob increased glucose and xylose yields by 22.1 % and 21.6 %, surpassing the commercial Ctec3 blend. This scalable approach significantly enhances biomass conversion and resource efficiency, offering broad industrial potential.

Green Synthesis of Fe2O3 Nanoparticles Using Eucalyptus globulus Leaf Extract on Pinus radiata Sawdust for Cationic Dye Adsorption

The present study reports the synthesis of Fe2O3 nanoparticles on Pinus radiata sawdust (Fe2O3@PS) using a Eucalyptus globulus leaf extract. The morphology and structure of Fe2O3@PS were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and UV-Vis diffuse reflectance. The adsorption capacity of the system was evaluated by testing its ability to remove the Rhodamine B (RhB) dye. The optimization of the system was carried out using the Plackett-Burman design (PBD) and the response surface methodology (steepest ascent and the Box-Behnken design), which provided information on the main parameters affecting the adsorption process. The PBD results showed that the most important parameters for the removal of RhB using Fe2O3@PS were the removal time, the RhB concentration, and the initial pH of the system. The reusability of Fe2O3@PS under optimal conditions was tested and it was found to maintain its efficiency after five cycles of use. The efficiency and rate of RhB removal observed at pH values near 7.0 were found to be predominantly influenced by electrostatic interactions. In contrast, the analyses conducted at pH values near 8.3 exhibited reduced influence from electrostatic attractions, with π-π interactions and hydrogen bonds emerging as dominant forces. At pH values exceeding 8.3, all potential interactions between RhB and Fe2O3@PS exhibited diminished strength. This research provides valuable information on the formation of eco-friendly nanoparticles immobilized on a forest residue such as sawdust, which can effectively remove organic pollutants like RhB. This contributes to the valorization of resources and the search for solutions to water pollution.

Exploring Corymbia torelliana hydrochar combustion kinetics through thermogravimetric analysis, peak deconvolution and reaction profile modelling

This study aims to conduct an applied and innovative investigation to enhance the energy quality of wood residues through hydrothermal carbonization pretreatment. For this purpose, the treatment was carried out at three different temperatures: 180, 220, and 240 °C under autogenous pressure. The in natura material and the hydrochars were characterized, and thermogravimetric analyses were performed in an O2 atmosphere with heating rates of 2.5, 5, 10, and 20 °C min-1. The global activation energy for natura biomass combustion was determined to be 112.49 kJ.mol-1. On the other hand, the hydrothermal carbonization process promoted a reduction in this value for the 94.85 kJ.mol-1. The conversion function for the in natura biomass was characterized as 1 - α , order 1, while the hydrochars was 2(1-α) [-ln(1-α)] (1⁄2), Avrami-Erofe'ev I. Triple kinetic parameters were ascertained, and the conversion curves along with their respective derivatives were modeled, exhibiting minimal deviations between theoretical and experimental data. This facilitated the mathematical representation of the reaction processes and allowed for a comprehensive comparison of the results.

Fundamental investigation of micro-nano cellulose and lignin interaction for transparent paper: Experiment and electrostatic potential calculation

Plastic has significant negative consequences for the environment and human health, demanding greener alternatives. Lignocellulose is a sustainable biomass material, and its paper has been considered as a potential material to replace plastics. Micro-nano lignocellulose, derived from natural plants, possesses a small size and abundant hydrogen bonding capacity. However, there is no clear explanation for the interactions between lignin and micro-nano cellulose, and little understanding of how the interaction can affect the papers' structure and optical properties. Electrostatic potential calculation is a reliable tool to explain non-covalent interactions, and can explore the binding between lignin and micro-nano cellulose. In this paper, kenaf - a non-wood fiber raw material - was employed to prepare micro-nano lignocellulose. The resulting slurry facilitated the production of transparent paper via a simple casting method. The prepared transparent micro-nano paper exhibited high transparency (~90 %), UVA resistance (~80 %), and hydrophobicity (~114°). More importantly, the electrostatic potential calculation demonstrates the inherent relationship between structure and performance, providing practical knowledge for constructing film materials.

Efficient hemicellulose removal from lignocellulose by induced electric field-aided dilute acid pretreatment

This study evaluated the effectiveness of induced electric field (IEF) as a novel electrotechnology to assist dilute acid pretreatment of wheat straw (WS) at atmospheric pressure and low temperature (90 °C). The effects of acid concentration and duration on cellulose recovery, hemicellulose and lignin removal were investigated. Meanwhile, the differences between IEF pretreatment and hydrothermal pretreatment were compared by quantitative and qualitative analysis. The optimal pretreatment condition was acid concentration 1 % with the period of 5 h. Under the parameters, the hemicellulose removal of WS after IEF pretreatment was up to 73.6 %, and the enzymatic efficiency was 55.8 %. In addition, the irregular surface morphology, diminished functional groups associated with hemicellulose, increased specific surface area and pore volume, as well as improved thermal stability of the residual WS support the remarkable effect of IEF pretreatment. The feasibility of IEF pretreatment is might be due to the fact that the magneto-induced electric field promotes ionization of H+ and formation of hydrated hydrogen ions, increasing the acidity of the medium. Secondly, electroporation disrupts the anti-degradation structure of WS and increases the accessibility of cellulose to cellulases. It indicated that IEF is a green and efficient strategy for assisting the separation of hemicellulose from lignocellulose.

Semi-continuous hydrothermal processing of pine sawdust for integrated production of fuels precursors and platform chemicals

This research reports data for the integrated obtaining of fermentable sugars (FSs), bio-oil (BO), and hydro-char (HC) - all fuel precursors - as well as platform chemicals (PCs - acetic, formic, and levulinic acid, besides furfural, and hydroxymethylfurfural) through semi-continuous hydrothermal processing of sawdust from pine wood. The influence of temperature (260, 300, and 340 °C) and the water-to-biomass ratio (25 and 50 g H2O (g biomass)-1) were the parameters considered to evaluate the mass yields, kinetic profiles, and BO properties. For FSs (and PCs), a detailed analysis considering the kinetic profiles of obtaining cellobiose, glucose, xylose, and arabinose is presented. For the conditions evaluated, a distinct behavior concerning the process parameters was observed, where 7.11 and 9.28 g (100 g biomass)-1 of FSs and PCs were synergistically obtained, respectively, after 30 min, 20 MPa, 260 °C, and 50 g H2O (g biomass)-1. Contextually, 17.59 g (100 g biomass)-1 of BO was obtained at 340 °C and the same water/biomass ratio. FTIR analysis of the BO samples suggested the presence of aldehydes, carboxylic acids, ketones, hydrocarbons, ethers as well as aromatic, alcohols, and nitrogenous compounds. Similar HC yields were achieved among the conditions analyzed, where 24.68 g (100 g biomass)-1 were obtained at 340 °C and 50 g H2O (g biomass)-1 for a higher heating value of 29.14 MJ kg-1 (1.5 times higher than the in natura biomass).

Pulp-paper industry sludge waste biorefinery for sustainable energy and value-added products development: A systematic valorization towards waste management

The pulp-paper industry is one of the main industrial sectors that produce massive amounts of residual sludge, constituting an enormous environmental burden for the industries. Traditional sludge management practices, such as landfilling and incineration, are restricted due to mounting environmental pressures, complex regulatory frameworks, land availability, high costs, and public opinion. Valorization of pulp-paper industry sludge (PPS) to produce high-value products is a promising substitute for traditional sludge management practices, promoting their reuse and recycling. Valorization of PPIS for biorefinery beneficiation includes biomethane, biohydrogen, bioethanol, biobutanol, and biodiesel production for renewable energy generation. Additionally, the various thermo-chemical technologies can be utilized to synthesize bio-oil, hydrochar, biochar, adsorbent, and activated carbon, signifying potential for value-added generation. Moreover, PPIS can be recycled as a byproduct by incorporating it into nanocomposites, cardboard, and construction materials development. This paper aims to deliver a comprehensive overview of PPIS management approaches and thermo-chemical technologies utilized for the development of platform chemicals in industry. Substitute uses of PPIS, such as making building materials, developing supercapacitors, and making cardboard, are also discussed. In addition, this article deeply discusses recent developments in biotechnologies for valorizing PPIS to yield an array of valuable products, such as biofuels, lactic acids, cellulose, nanocellulose, and so on. This review serves as a roadmap for future research endeavors in the effective handling of PPIS.

Bioprospecting CAZymes repertoire of Aspergillus fumigatus for eco-friendly value-added transformations of agro-forest biomass

BACKGROUND

Valorizing waste residues is crucial to reaching sustainable development goals and shifting from a linear fossil-based economy to a circular economy. Fungal cell factories, due to their versatility and robustness, are instrumental in driving the bio-transformation of waste residues. The present work isolated a potent strain, i.e., Aspergillus fumigatus (ZS_AF), from an ancient Złoty Stok gold mine, which showcased distinctive capabilities for efficient hydrolytic enzyme production from lignocellulosic wastes.

RESULTS

The present study optimized hydrolytic enzyme production (cellulases, xylanases, and β-glucosidases) from pine sawdust (PSD) via solid-state fermentation using Aspergillus fumigatus (ZS_AF). The optimization, using response surface methodology (RSM), produced a twofold increase with maximal yields of 119.41 IU/gds for CMCase, 1232.23 IU/gds for xylanase, 63.19 IU/gds for β-glucosidase, and 31.08 IU/gds for FPase. The secretome profiling validated the pivotal role of carbohydrate-active enzymes (CAZymes) and auxiliary enzymes in biomass valorization. A total of 77% of carbohydrate-active enzymes (CAZymes) were constituted by glycoside hydrolases (66%), carbohydrate esterases (9%), auxiliary activities (3%), and polysaccharide lyases (3%). The saccharification of pretreated wheat straw and PSD generated high reducing sugar yields of 675.36 mg/g and 410.15 mg/g, respectively.

CONCLUSION

These findings highlight the significance of an efficient, synergistic, and cost-effective arsenal of fungal enzymes for lignocellulosic waste valorization and their potential to contribute to waste-to-wealth creation through solid-waste management. The utilization of Aspergillus fumigatus (ZS_AF) from an unconventional origin and optimization strategies embodies an innovative approach that holds the potential to propel current waste valorization methods forward, directing the paradigm toward improved efficiency and sustainability.

Co-hydrothermal carbonization of pine residual sawdust and non-dewatered sewage sludge - effect of reaction conditions on hydrochar characteristics

Waste valorization is mandatory to develop and consolidate a circular bioeconomy. It is necessary to search for appropriate processes to add value to different wastes by utilizing them as feedstocks to provide energy, chemicals, and materials. For instance, hydrothermal carbonization (HTC) is an alternative thermochemical process that has been suggested for waste valorization aiming at hydrochar production. Thus, this study proposed the Co-HTC of pine residual sawdust (PRS) with non-dewatered sewage sludge (SS) - two wastes largely produced in sawmills and wastewater treatment plants, respectively - without adding extra water. The influence of temperature (180, 215, and 250 °C), reaction time (1, 2, and 3 h), and PRS/SS mass ratio (1/30, 1/20, and 1/10) on the yield and characteristics of the hydrochar were evaluated. The hydrochars obtained at 250 °C had the best coalification degree, showing the highest fuel ratio, high heating value (HHV), surface area, and N, P, and K retention, although presenting the lowest yields. Conversely, hydrochar functional groups were generally reduced by increasing Co-HTC temperatures. Regarding the Co-HTC effluent, it presented acidic pH (3.66-4.39) and high COD values (6.2-17.3 g·L^-1). In general, this new approach could be a promising alternative to conventional HTC, in which a high amount of extra water is required. Besides, the Co-HTC process can be an option for managing lignocellulosic wastes and sewage sludges while producing hydrochar. This carbonaceous material has the potential for several applications, and its production is a step towards a circular bioeconomy.

Structural characterization of lignin-carbohydrate complexes from Chinese quince fruits extracted after enzymatic hydrolysis pretreatment

Chinese quince fruit (CQF) contains abundant pectin; however, the pectin cannot be efficiently separated by conventional approaches because of strong lignin-carbohydrate complexes (LCC). In this study, to elucidate the structural characteristics of the original LCC formed by lignin and pectin in CQF, single and multiple enzymatic hydrolysis pretreatments were innovatively performed, and the resulting LCC preparations were comprehensively characterized using a series of techniques. The enzymatic hydrolysis pretreatments significantly increase the LCC yield, releasing LCC fractions with low molecular weights (Mw = 4660-8288 Da). LCC-4, isolated by pretreatment with cellulase plus xylanase, had the highest galacturonic acid content (15.5 %), followed by LCC-2 (isolated by xylanase pretreatment) of 14.0 %. In CQF, lignin develops lignin-carbohydrate (LC) bonds with pectin to form LCC, with phenyl-glycoside bond being the dominant linkage. Although the pectinase pretreatment reduced the pectin content, signals of the LC linkages in the 2D-HSQC spectra were enhanced. LCC-4 could be considered as the most representative of the original LCC in CQF due to its high pectin content and multiple LCC signals in the 2D-HSQC spectrum. The structural understanding of the original LCC in CQF will lay a foundation for designing appropriate methods for extracting pectin from CQF.

Eco-Friendly Methods for Extraction and Modification of Cellulose: An Overview

Cellulose is the most abundant renewable polymer on Earth and can be obtained from several different sources, such as trees, grass, or biomass residues. However, one of the issues is that not all the fractionation processes are eco-friendly and are essentially based on cooking the lignocellulose feedstock in a harsh chemical mixture, such as NaOH + Na₂S, and water, to break loose fibers. In the last few years, new sustainable fractionation processes have been developed that enable the obtaining of cellulose fibers in a more eco-friendly way. As a raw material, cellulose's use is widely known and established in many areas. Additionally, its products/derivatives are recognized to have a far better environmental impact than fossil-based materials. Examples are textiles and packaging, where forest-based fibers may contribute to renewable and biodegradable substitutes for common synthetic materials and plastics. In this review, some of the main structural characteristics and properties of cellulose, recent green extraction methods/strategies, chemical modification, and applications of cellulose derivatives are discussed.

A review on hydrothermal carbonization of potential biomass wastes, characterization and environmental applications of hydrochar, and biorefinery perspectives of the process

It is imperative to search for appropriate processes to convert wastes into energy, chemicals, and materials to establish a circular bio-economy toward sustainable development. Concerning waste biomass valorization, hydrothermal carbonization (HTC) is a promising route given its advantages over other thermochemical processes. From that perspective, this article reviewed the HTC of potential biomass wastes, the characterization and environmental utilization of hydrochar, and the biorefinery potential of this process. Crop and forestry residues and sewage sludge are two categories of biomass wastes (lignocellulosic and non-lignocellulosic, respectively) readily available for HTC or even co-hydrothermal carbonization (Co-HTC). The temperature, reaction time, and solid-to-liquid ratio utilized in HTC/Co-HTC of those biomass wastes were reported to range from 140 to 370 °C, 0.05 to 48 h, and 1/47 to 1/1, respectively, providing hydrochar yields of up to 94 % according to the process conditions. Hydrochar characterization by different techniques to determine its physicochemical properties is crucial to defining the best applications for this material. In the environmental field, hydrochar might be suitable for removing pollutants from aqueous systems, ameliorating soils, adsorbing atmospheric pollutants, working as an energy carrier, and performing carbon sequestration. But this material could also be employed in other areas (e.g., catalysis). Regarding the effluent from HTC/Co-HTC, this byproduct has the potential for serving as feedstock in other processes, such as anaerobic digestion and microalgae cultivation. These opportunities have aroused the industry interest in HTC since 2010, and the number of industrial-scale HTC plants and patent document applications has increased. The hydrochar patents are concentrated in China (77.6 %), the United States (10.6 %), the Republic of Korea (3.5 %), and Germany (3.5 %). Therefore, considering the possibilities of converting their product (hydrochar) and byproduct (effluent) into energy, chemicals, and materials, HTC or Co-HTC could work as the first step of a biorefinery. And this approach would completely agree with circular bioeconomy principles.

Biochar and hydrochar in the context of anaerobic digestion for a circular approach: An overview

Biochar and hydrochar are carbonaceous materials with valuable applications. They can be synthesized from a wide range of organic wastes, including digestate. Digestate is the byproduct of anaerobic digestion (AD), which is performed for bioenergy (biogas) production from organic residues. Through a thermochemical process, such as pyrolysis, gasification, and hydrothermal carbonization - HTC, digestate can be converted into biochar or hydrochar. The addition of either biochar or hydrochar in AD has been reported to improve biochemical reactions and microbial growth, increasing the buffer capacity, and facilitating direct interspecies electrons transfer (DIET), resulting in higher methane (CH₄) yields. Both biochar and hydrochar can adsorb undesired compounds present in biogas, such as carbon dioxide (CO₂), hydrogen sulfide (H₂S), ammonia (NH₃), and even siloxanes. However, an integrated understanding of biochar and hydrochar produced from digestate through their return to the AD process, as additives or as adsorbents for biogas purification, is yet to be attained to close the material flow loop in a circular economy model. Therefore, this overview aimed at addressing the integration of biochar and hydrochar production from digestate, their utilization as additives and effects on AD, and their potential to adsorb biogas contaminants. This integration is supported by life cycle assessment (LCA) studies, showing positive results when combining AD and the aforementioned thermochemical processes, although more LCA is still necessary. Techno-economic assessment (TEA) studies of the processes considered are also presented, and despite an expanding market of biochar and hydrochar, further TEA is required to verify the profitability of the proposed integration, given the specificities of each process design. Overall, the synthesis of biochar and hydrochar from digestate can contribute to improving the AD process, establishing a cyclic process that is in agreement with the circular economy concept.

Biotechnological advances in biomass pretreatment for bio-renewable production through nanotechnological intervention

Globally, the fossil fuel reserves are depleting rapidly and the escalating fuel prices as well as plethora of the pollutants released from the emission of burning fossil fuels cause global warming that massively disturb the ecological balance. Moreover, the unnecessary utilization of non-renewable energy sources is a genuine hazard to nature and economic stability, which demands an alternative renewable source of energy. The lignocellulosic biomass is the pillar of renewable sources of energy. Different conventional pretreatment methods of lignocellulosic feedstocks have employed for biofuel production. However, these pretreatments are associated with disadvantages such as high cost of chemical substances, high load of organic catalysts or mechanical equipment, time consuming, and production of toxic inhibitors causing the environmental pollution. Nanotechnology has shown the promised biorefinery results by overcoming the disadvantages associated with the conventional pretreatments. Recyclability of nanomaterials offers cost effective and economically viable biorefineries processes. Lignolytic and saccharolytic enzymes have immobilized onto/into the nanomaterials for the higher biocatalyst loading due to their inherent properties of high surface area to volume ratios. Nanobiocatalyst enhance the hydrolyzing process of pretreated biomass by their high penetration into the cell wall to disintegrate the complex carbohydrates for the release of high amounts of sugars towards biofuel and various by-products production. Different nanotechnological routes provide cost-effective bioenergy production from the rich repertoires of the forest and agricultural-based lignocellulosic biomass. In this article, a critical survey of diverse biomass pretreatment methods and the nanotechnological interventions for opening up the biomass structure has been carried out.

Integrated pretreatment of banana agrowastes: Structural characterization and enhancement of enzymatic hydrolysis of cellulose obtained from banana peduncle

An integrated treatment coupling alkali, steam explosion and ammonia/chlorine-free bleaching with sequential mild acid pretreatment were performed to isolate and characterize cellulose from banana agrowastes followed by optimized enzymatic hydrolysis to glucose. The cellulose yield, compositional, microstructural, and morphological analysis initially obtained from three post-harvest banana agrowastes (peel, pseudostem, and peduncle) were surveyed. Isolation parameters for banana peduncle agrowastes, the most efficient precursor, were reconfigured for acid hydrolysis by applying an orthogonal L₉ array of Taguchi design. Effects of solution-to-pulp ratio, acid concentration, temperature, and reaction time on physicochemical parameters were assessed resulting in ~81% cellulose recovery. Subsequently, cellulase driven enzymatic conversion to glucose was modelled using response surface methodology (RSM), where the mutual influences of incubation time, enzyme concentration, substrate concentration, and surfactant concentration were investigated. Artificial Neural Network (ANN) modelling further improved upon RSM optimizations ensuing ~97% optimized glucose yield, verified experimentally.

A review on physico-chemical delignification as a pretreatment of lignocellulosic biomass for enhanced bioconversion

Effective pretreatment of lignocellulosic biomass (LCB) is one of the most important steps in biorefinery, ensuring the quality and commercial viability of the overall bioprocess. Lignin recalcitrance in LCB is a major bottleneck in biological conversion as the polymerization of lignin with hemicellulose hinders enzyme accessibility and further bioconversion to fuels and chemicals. Therefore, there is a need to delignify LCB to ease further bioprocessing. The efficiency of delignification, quality and quantity of the desired products, and generation of inhibitors depend upon the type of pretreatment employed. This review summarizes different single and integrated physicochemical pretreatments for delignification. Additionally, conditions required for effective delignification and the advantages and drawbacks of each method were evaluated. Advances in overcoming the recalcitrance of residual lignin to saccharification and the methods to recover lignin after delignification are also discussed. Efficient lignin recovery and valorization strategies provide an avenue for the sustainable lignocellulose biorefinery.

Structural changes of lignin-carbohydrate complexes (LCCs) from Chinese quince fruits during the sequential fractionation of pectic and hemicellulosic polysaccharides

Chinese quince (Chaenomeles sinensis) fruits offer a potential source of pectin and hemicellulose. However, the existence of lignin-carbohydrate complexes (LCCs) can negatively impact the extraction of pectin and hemicellulose. In this work, LCCs were sequentially fractionated from Chinese quince during the removal of pectin and hemicellulose. The structures of LCCs were characterized by HPAEC, FT-IR, GPC, Py-GC/MS, TGA and 2D HSQC NMR. The results showed that the carbohydrate content and molecular weight of LCCs was found to be changed significantly after the removal of hemicellulose (KSH). The lignin in Björkman LCCs was found to be linked mainly to galactan and fructan, whereas the lignin LCC-AcOHs was found to be linked mainly to arabinan after the removal of KSH. The isolation of carbonate-soluble pectin (NSP) increased thermal stability of Björkman LCC fraction, however, the isolation of chelator-soluble pectin (CSP) increased the thermal stability of LCC-AcOHs. The S/G ratios of LCC-AcOHs increased and large amounts of S-type lignin released during sequential fractionation of pectin and hemicellulose. These results will be beneficial for understanding the mechanisms of pectin and hemicellulose isolation, thereby facilitating the potential application of Chinese quince as a valuable natural resource for food and other industries.

Cellulose extraction of Alstonia scholaris: A comparative study on efficiency of different bleaching reagents for its isolation and characterization

The incredible benefits of Alstonia scholaris are piquing researchers' attention in extracting its cellulose and utilizing it in further therapeutic applications. This study is based on cellulose extraction from its stalks and processed through chemical pre-treatments to manifest its cellulose content by using different bleaching reagents. A comparison was made on efficiencies of three reagents and it is found that the hydrogen peroxide exposed maximum cellulose than sodium hypochlorite and sodium chlorite. The experimental results revealed that A. scholaris possess 68-70% cellulose content. FTIR spectrum shows that OH- and CH- vibrations of cellulose appeared at 3320 cm-1 & 2892 cm-1 respectively whereas SEM images show fibrillation, rough surface, and lumens in bleached fiber that attributes to the removal of lignin and hemicelluloses and confirms cellulose extraction. The XRD pattern certifies the crystalline nature and compactness of cellulose whereas tensile properties and TGA help in understanding its flexibility, mechanical strength, and thermal stability at 370 °C respectively.

Isolation and Characterization of a Novel Laccase for Lignin Degradation, LacZ1

Lignin is a complex natural organic polymer and is one of the primary components of lignocellulose. The efficient utilization of lignocellulose is limited because it is difficult to degrade lignin. In this study, we screened a lacz1 gene fragment encoding laccase from the macrotranscriptome data of a microbial consortium WSC-6, which can efficiently degrade lignocellulose. The reverse transcription-quantitative PCR (RT-qPCR) results demonstrated that the expression level of the lacz1 gene during the peak period of lignocellulose degradation by WSC-6 increased by 30.63 times compared to the initial degradation period. Phylogenetic tree analysis demonstrated that the complete lacz1 gene is derived from a Bacillus sp. and encoded laccase. The corresponding protein, LacZ1, was expressed and purified by Ni-chelating affinity chromatography. The optimum temperature was 75°C, the optimum pH was 4.5, and the highest enzyme activity reached 16.39 U/mg. We found that Cu²⁺ was an important cofactor needed for LacZ1 to have enzyme activity. The molecular weight distribution of lignin was determined by gel permeation chromatography (GPC), and changes in the lignin structure were determined by ¹H nuclear magnetic resonance (¹H NMR) spectra. The degradation products of lignin by LacZ1 were determined by gas chromatography and mass spectrometry (GC-MS), and three lignin degradation pathways (the gentian acid pathway, benzoic acid pathway, and protocatechuic acid pathway) were proposed. This study provides insight into the degradation of lignin and new insights into high-temperature bacterial laccase. IMPORTANCE Lignin is a natural aromatic polymer that is not easily degraded, hindering the efficient use of lignocellulose-rich biomass resources, such as straw. Biodegradation is a method of decomposing lignin that has recently received increasing attention. In this study, we screened a gene encoding laccase from the lignocellulose-degrading microbial consortium WSC-6, purified the corresponding protein LacZ1, characterized the enzymatic properties of laccase LacZ1, and speculated that the degradation pathway of LacZ1 degrades lignin. This study identified a new, high-temperature bacterial laccase that can degrade lignin, providing insight into lignin degradation by this laccase.

Green, efficient extraction of bamboo hemicellulose using freeze-thaw assisted alkali treatment

The premise of high value utilization of lignocellulosic biomass is effective separation of hemicellulose. In this paper, the extraction of bamboo hemicellulose using freeze-thaw assisted alkali treatment (FAT) was studied. The effect of alkali concentration, alkali treatment time, freezing temperature, and freeze-thaw time on the main components was studied. Bamboo was frozen at -30 °C for 12 h, thawed at room temperature, and then treated at 75 °C for 90 min with 7.0% alkali. The extraction rate of hemicellulose was as high as 64.71%. The purity of hemicellulose samples using conventional AT decreased from 82.63% to 78.56%. Hemicellulose with the same yield as that of conventional alkali treatment was obtained by further reducing the alkali concentration. The purity of hemicellulose samples increased from 82.63% to 89.45%. It had a higher purity, higher molecular weight, and lower polydispersity. A new, green and efficient alkaline extraction method for hemicellulose was developed.

Evaluation and Characterization of Timber Residues of Pinus spp. as an Energy Resource for the Production of Solid Biofuels in an Indigenous Community in Mexico

This study shows the energy potential of pine wood waste for the production of solid biofuels, and was carried out in an indigenous community in the state of Michoacán. One of the main economic activities of this community is the production of handcrafted furniture, which generates a large amount of wood waste. The most relevant results obtained in this research show that the community generates approximately 2268 kg of sawdust and 5418 kg of shavings per week, and the estimated energy potential per year for both sawdust is 1.94 PJ and for shaving is 4.65 PJ. Based on the particle size observed, the wood residue can be used to generate pellets or briquettes. Other average results in sawdust and (shavings) are the following: initial moisture content 15.3% (16.8%), apparent density 169.23 kg/m3 (49.25 kg/m3), ash 0.43% (0.42%), volatile material 84.9% (83.60%), fixed carbon 14.65% (15.96%), hemicelluloses 12.89% (10.68%), cellulose 52.68% (52.82%), lignin 26.73% (25.98%), extractives 7.69% (10.51%), calorific value 17.6 MJ/kg (17.9 MJ/kg). The major chemical elements in the ash were Al, K. Fe, Ca, P, Na, and Mg. Finally, the results obtained indicate that this biomass can be used to generate pellets or briquettes in this indigenous community.