Search Results (210)

Xyloglucan, a key component of plant cell wall polysaccharides, plays a crucial role in cell wall structural remodeling and biomass recalcitrance. This study reports the discovery and biochemical characterization of a novel glycoside hydrolase family 12 (GH12) xyloglucanase, TpXEG12a, from the biomass-degrading fungus Talaromyces pinophilus. Recombinant TpXEG12a exhibited exceptional catalytic efficiency toward xyloglucan, with a specific activity of 2375 U/mg, significantly higher than the typical range reported for GH12 xyloglucanases. The enzyme displayed optimal activity at pH 4.0 and 57 °C, with high stability in acidic conditions (pH 4–8) and moderate thermal stability. TpXEG12a demonstrated strict substrate specificity for xyloglucan, with no detectable activity against cellulose-related substrates, and primarily generated characteristic xyloglucan oligosaccharides (XXXG, XLXG/XXLG, XLLG) upon hydrolysis. Structural analysis revealed that TpXEG12a exists as a stable homodimer in solution, which likely contributes to its catalytic efficiency. Notably, TpXEG12a synergistically enhanced glucose release when combined with cellulase in lignocellulosic biomass degradation. These findings establish TpXEG12a as a promising candidate for industrial applications in biomass conversion, textile processing, and functional oligosaccharide production. Full article

Rice husk (RH) is a widely available lignocellulosic residue for biohydrogen production but requires effective pretreatment to overcome lignin-related recalcitrance. This study investigates the kinetics of lignin removal from RH using 3% sodium hydroxide (NaOH) and water pretreatments at high temperatures between 100 and 129 °C (25 °C control) with short reaction times (15–60 min) in an autoclave system. Biomass composition, solid yield, delignification efficiency, and enzymatic hydrolysis for glucose production were evaluated. NaOH pretreatment achieved up to 72.72% lignin removal at 129 °C after 60 min, significantly outperforming water pretreatment, which reached a maximum delignification of 20.24% under the same conditions. Kinetic analysis revealed first-order reaction behavior, with the kinetic rate constants varying between 5.14 × 10⁻⁵ and 4.31 × 10⁻³ with water pretreatment and from 3.73 × 10⁻⁴ to 2.46 × 10⁻² with NaOH and activation energies of 42.61 kJ mol⁻¹ K⁻¹ and 39.31 kJ mol⁻¹ K⁻¹ for water and NaOH pretreatment, respectively. Enhanced lignin removal improved cellulose accessibility, resulting in glucose yields from enzymatic hydrolysis of up to 52.13 mg/g for NaOH-treated samples, double those obtained with water pretreatment (26.97 mg/g). While NaOH pretreatment achieved higher lignin removal efficiency and glucose yield, it exhibited significantly higher environmental impacts across multiple categories, including global warming potential and terrestrial ecotoxicity, based on the life cycle assessment (LCA). Even water-based pretreatment showed considerable burdens; thus, both pretreatment methods impose high life cycle impacts when applied to RH, which makes it an unsustainable feedstock for glucose production under the evaluated conditions. Alternative feedstocks or improved process integration strategies are required for environmentally viable biohydrogen production. Full article

Soil organic carbon (SOC) plays a crucial role in climate change mitigation by regulating atmospheric CO₂ and maintaining ecosystem balance; however, its stability is influenced by land use in anthropized areas such as the tropical Andes. This study developed a dynamic compartmental model based on ordinary differential equations to simulate carbon fluxes among litter, humus, and microbial biomass under four land uses in the Las-Piedras River basin (Popayán, Colombia): riparian forest (RF), ecological restoration (ER), natural-regeneration (NR), and livestock (LS). The model includes two decomposition rate constants: k₁, for the transformation of fresh organic matter, and k₂, for the turnover of humified organic matter. It was calibrated using field data on soil physicochemical and biological properties, as well as carbon inputs and outputs. The results showed clear differences in SOC dynamics among land uses: RF had the highest SOC stocks (148.7 Mg ha⁻¹) and microbial biomass, while LS showed the lowest values and the greatest deviation due to compaction and low residue input. The humus fraction remained the most stable pool (k₂ ≈ 10⁻⁴ month⁻¹), confirming its recalcitrant nature. Overall, the model reproduced SOC behavior accurately (MAE = 0.01–0.30 Mg ha⁻¹) and provides a framework for improving soil carbon management in mountain ecosystems. Full article

Chinese cabbage (Brassica rapa ssp. pekinensis) is a globally important leafy vegetable, but functional genomics research on its recalcitrance to Agrobacterium-mediated genetic transformation is severely limited. In this study, we demonstrate that both Agrobacterium infection and antibiotic selection significantly inhibit cotyledonary petiole regeneration, representing one principal bottleneck to high-throughput transformation. Infection with different Agrobacterium strains suppressed the regenerated shoot per explant by 30.98–69.16%. Supplying the salicylic acid signaling inhibitor tenoxicam in the seed germination medium raised post-infection regeneration by up to 37.90%. Compared with non-infected controls, the optimal NAA concentration for explant regeneration after infection was higher, and 0.5 mg/L increased post-infection regeneration by 27.66%. Replacing antibiotic selectable markers with the visual reporter eYGFPuv or RUBY eliminated phytotoxicity, reduced false-positive shoots, and further elevated transformation efficiency to 19.33–20.00% (versus 2.67–6.67% under antibiotic selection). The integrated protocol yielded stable RUBY overexpressing lines, the biomass of which declined with rising transcript levels. Restricting RUBY expression to the inner head leaves generated a novel germplasm with less yield penalty. This work provides a high-efficiency transformation method that will accelerate gene discovery and genome editing in Chinese cabbage. Full article

Straw return is a potential practice for adsorbing salt and retaining moisture in saline–alkali soils. However, adverse climate conditions such as prolonged drought and cold winters shorten the effective structural turnover of returned straw biomass in soils. Furthermore, the rigid crystalline cell walls and recalcitrant lignin components of undecomposed plant residues lower the adsorption capacity towards salt. Here, we report the pretreatment of neutral oxalic acid to destroy the dense crystalline structure of cotton straw cellulose. Through laboratory experiments, combined with the changes in the structural and chemical properties of cotton straw, the optimal oxalic acid pretreatment (OAC) conditions were determined. Subsequently, the application effectiveness of OAC was evaluated via pot experiments and field trials. The optimal conditions of OAC were 0.2% dosage, 60 °C, and 24 h, displaying a maximum increase in salt absorption and water retention capacities of cotton straw materials, through exposing the hydroxyl network of cellulose and chemically hydrolyzing recalcitrant lignin. In the indoor potted plant experiments, the feasible application of oxalic acid pretreatment can be regarded as an active barrier, increasing soil moisture by 16–43% and reducing total salts by 23–26% in the topsoil (0–20 cm) within a 45-day laboratory incubation. Additionally, the OAC pretreatment had negligible adverse impacts on soil microbial communities. Moreover, some plant-beneficial microbes (e.g., Sphingomonadaceae and Gemmatimonadaceae) were stimulated, with their relative abundance increasing by 26–40% and 27–63%, respectively. Ultimately, under the pretreatment of oxalic acid-modified cotton straw salt-absorbing water-retention agent (OAC-SR), cotton seedling emergence rates, plant height, and biomass all increased to varying degrees across different concentrations of saline–alkali soil (0.05–1.0%) in the field. Then OAC-SR can be potentially applied to the process of cotton straw return to facilitate the turnover of straw structure in soil, enhance the salt-adsorption and water-retention capacities of returned straw, and provide a low-salt microenvironment for crop growth. This study demonstrates a further low-carbon and in situ applicable route to accelerate the destruction of cotton straw structure, thereby alleviating crop salt damage and promoting the green circular development of saline–alkali soil remediation. Full article

Olive tree pruning (OTP), a widely available agricultural residue in Mediterranean countries, represents a promising lignocellulosic feedstock for anaerobic digestion. However, its recalcitrant structure limits its biodegradability and methane yields, necessitating effective pretreatment approaches. In this context, hydrogen peroxide in combination with ultraviolet (UV) radiation (UV/H₂O₂) at ambient temperature was used as a pretreatment method for enhancing methane production from OTP. Three concentrations of H₂O₂ (0, 1, and 3% w/w) alone or in combination with UV radiation, at different retention times (8, 14, and 20 h), were evaluated to enhance OTP depolymerization and methane generation. In addition, the combination of UV/H₂O₂ with alkali (UV/H₂O₂/NaOH) was compared with the typical alkaline pretreatment (NaOH) in terms of lignocellulosic biomass fractionation and biochemical methane potential (BMP). Results showed that increasing H₂O₂ concentration during UV/H₂O₂ pretreatment enhanced hemicellulose solubilization. Both NaOH and UV/H₂O₂/NaOH pretreatment promoted lignin reduction (37.3% and 37.8%), resulting in enhanced BMP values of 330.5 and 337.9 L CH₄/kg TS, respectively. Considering operational energy requirements (heating at 80 °C and irradiance for 20 h) and methane energy recovery, net energy balances of 45.52 kJ and 66.65 kJ were obtained for NaOH and UV/H₂O₂/NaOH, respectively. Full article

Lignocellulosic biomass—the non-edible fraction of plants composed of cellulose, hemicellulose, and lignin—is the most abundant renewable carbon resource and a key lever for shifting from fossil to bio-based production. Agro-industrial residues (straws, cobs, shells, bagasse, brewery spent grains, etc.) offer low-cost, widely available feedstocks but are difficult to process because their polymers form a tightly integrated, three-dimensional matrix. Within this matrix, lignin provides rigidity, hydrophobicity, and defense, yet its heterogeneity and recalcitrance impede saccharification and upgrading. Today, most technical lignin from pulping and emerging biorefineries is burned for energy, despite growing opportunities to valorize it directly as a macromolecule (e.g., adhesives, foams, carbon precursors, UV/antioxidant additives) or via depolymerization to low-molecular-weight aromatics for fuels and chemicals. Extraction route and severity strongly condition lignin structure linkages (coumaryl-, coniferyl-, and sinapyl-alcohol ratios), determining reactivity, solubility, and product selectivity. Advances in selective fractionation, reductive/oxidative catalysis, and hybrid chemo-biological routes are improving yields while limiting condensation. Remaining barriers include feedstock variability, solvent and catalyst recovery, hydrogen and energy intensity, and market adoption (e.g., low-emission adhesives). Elevating lignin from fuel to product within integrated biorefineries can unlock significant environmental and economic benefits. Full article

The growing global demand for clean energy and sustainability has increased interest in lignocellulosic biomass as a viable alternative to conventional fossil fuels. Among the various biomass resources, sugarcane bagasse, an abundant agro-industrial by-product, has emerged as a promising feedstock to produce renewable fuels and value-added chemicals. Its high carbohydrate content offers significant potential for bioconversion. However, its complex and recalcitrant lignocellulosic matrix presents significant challenges that necessitate advanced pretreatment techniques to improve enzymatic digestibility and fermentation efficiency. This review consolidates recent developments in the valorization of sugarcane bagasse focusing on innovative pretreatment and fermentation strategies for sustainable bioethanol production. It emphasizes the synergistic benefits of integrating various pretreatment and fermentation methods to improve bioethanol yields, reduce processing costs and enhance overall process sustainability. This review further explores recent technological advancements, the impact of fermentation inhibitor, and emerging strategies to overcome these challenges through microbial strains and innovative fermentation methods. Additionally, it highlights the multi-faceted advantages of bagasse valorization, including waste minimization, renewable energy production and the promotion of sustainable agricultural practices. By evaluating the current state of research and outlining future perspectives, this paper serves as a comprehensive guide to advancing the valorization of sugarcane bagasse in the transition towards a low-carbon economy. The novelty of this review lies in its holistic integration of technological, economic, and policy perspectives, uniquely addressing the scalability of integrated pretreatment and fermentation processes for sugarcane bagasse, and outlining practical pathways for their translation from laboratory to sustainable industrial biorefineries within the circular bioeconomy framework. Full article

Anaerobic digestion is a well-known technology for renewable energy generation. Its efficiency depends on the substrate composition and its biodegradability. Microalgae are considered a promising feedstock due to their rapid growth, high protein and lipid content, and potential for wastewater treatment. However, the mono-digestion is often limited by a low carbon-to-nitrogen (C/N) ratio and a recalcitrant cell wall structure. This study evaluated the potential of co-digesting microalgal biomass with bakery waste under batch conditions. Two types of bakery residues (stale wheat bread and stale wheat rolls), were tested. Each was added to the microalgal biomass at proportions of 25%, 50%, and 75% based on volatile solids (VS). The experiment was carried out in a semi-technical anaerobic digester under mesophilic conditions. During the anaerobic digestion, the biogas volume, gas composition, and the energy potential of the substrates were analysed. The highest biogas yield (494.34 L·kg⁻¹ VS) was obtained from the mixture of microalgae and 75% bread. Although mono-digestion of microalgal biomass resulted in the highest methane concentration, the differences compared to co-digested samples were not significant. The lowest hydrogen sulphide concentration (234.20 ppm) was measured in the 25% rolls variant, while the control sample (100% microalgae) showed the highest H₂S levels. From an energy perspective, the most beneficial result was obtained with the addition of 75% bread. Full article

Microorganisms exhibit metabolic versatility, which enables their multifaceted application, including in pollutant detoxification, waste recycling, and environmental restoration. Agricultural processing generates substantial byproducts rich in carbon, nitrogen, and sulfur, which require proper handling to mitigate ecological challenges and reduce carbon footprints. The generation of recalcitrant keratinous biomass and its slow degradation in the environment have prompted technological interventions for sustainable solutions. Fundamentally, chemical, thermal and mechanical processing methods have been utilized in managing keratinous waste. These approaches are not only energy-intensive but also yield low-quality products and exacerbate environmental challenges. Multidimensional research on the microbial-assisted conversion of keratinous waste into valuable products, which aligns with circular economy principles, is underway. The biodegradation of keratinous resources has predominantly employed culturable single microbial strains; however, few studies have recently investigated microbial consortia as a promising strategy. The use of microbial consortia leverages the high cultural stability and complementary metabolic pathways of microbes to achieve excellent keratin biodegradation. Therefore, this study examined the latest advancements in transforming keratinous waste into high-quality protein hydrolysates using microbial strains. It detailed various types of microbial consortia and their roles in the valorization of keratinous biomass, while highlighting some knowledge gaps for future studies. The study also explored the role of ancillary microbial enzymes in facilitating the conversion of keratinous biomass into value-added products. Full article

Microwave pretreatment (MWP) has emerged as a promising strategy to enhance the pyrolysis of lignocellulosic biomass due to its rapid, volumetric, and selective heating. By disrupting the recalcitrant structure of cellulose, hemicellulose, and lignin, MWP improves biomass deconstruction, increases carbohydrate accessibility, and enhances yields of bio-oil, syngas, and biochar. When combined with complementary pretreatments—such as alkali, acid, hydrothermal, ultrasonic, or ionic-liquid methods—MWP further reduces activation energies, facilitating more efficient saccharification and thermal conversion. This review systematically evaluates scientific progress in this field through bibliometric analysis, mapping research trends, evolution, and collaborative networks. Key research questions are addressed regarding the technical advantages of MWP, the physicochemical transformations induced in biomass, and associated environmental benefits. Findings indicate that microwave irradiation promotes hemicellulose depolymerization, reduces cellulose crystallinity, and weakens lignin–carbohydrate linkages, which facilitates subsequent thermal decomposition and contributes to improved pyrolysis efficiency and product quality. From an environmental perspective, MWP contributes to energy savings, mitigates greenhouse gas emissions, and supports the integration of renewable electricity in biomass conversion. Full article

Keratinous biomass, such as feathers, wool, and hair, poses environmental challenges due to its insoluble and recalcitrant nature. In this study, we identified, purified and comprehensively characterized a previously uncharacterized extracellular alkaline keratinase, KerFJ, secreted by Bacillus sp. FJ-3-16, with broad industrial application potential. KerFJ was produced at high yield (1800 U/mL) in an optimized cost-effective medium and purified to homogeneity using ion-exchange chromatography. The enzyme exhibited optimal activity at pH 9.5 and 55 °C, with remarkable alkaline and thermal stability, and high tolerance to surfactants, oxidants, and metal ions. Sequence analysis revealed that KerFJ is a member of the serine peptidase S8 family, with a molecular weight of ~27.5 kDa. It efficiently degraded native keratin substrates, achieving 70.3 ± 2.1% feather, 39.7 ± 1.8% wool, and 15.4 ± 1.2% hair degradation, and the resulting feather hydrolysates exhibited strong antioxidant activities. KerFJ also demonstrated excellent compatibility with commercial detergents and enabled effective stain removal from fabrics without damage. Moreover, both laboratory- and pilot-scale trials showed that KerFJ facilitated non-destructive dehairing of sheep, donkey, and pig skins while preserving collagen integrity. These results highlight KerFJ as a robust and multifunctional biocatalyst suitable for keratin waste valorization, eco-friendly leather processing, and detergent formulations. Full article

Poplar (Populus L. species), a fast-growing temperate species, forms plantations with high productivity and biomass, with its litter sustaining key functions in nutrient cycling, microbial diversity, and carbon storage. Litter microbial communities drive decomposition, particularly in early stages, this initial phase is characterized by the leaching of water-soluble carbon and nutrients from the litter, which creates a readily available resource pulse that facilitates rapid microbial colonization and activation. This process is followed by the activation of microbial enzymes and the immobilization of nutrients, collectively initiating the breakdown of more recalcitrant litter materials. Under rising global nitrogen deposition, we conducted a field randomized block experiment in 13-year-old pure poplar (Populus deltoides L. ‘35’) stands, with three nitrogen addition treatments: N0 (0 g N·m⁻²·yr⁻¹), N2 (10 g N·m⁻²·yr⁻¹), and N4 (30 g N·m⁻²·yr⁻¹). In the initial phase of litter decomposition, we measured the soil properties and litter traits, the litter microbial community composition, and its taxonomic and phylogenetic diversity indices. The results indicate that nitrogen addition altered microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), soil NO₃⁻-N, and accelerated litter decomposition rates. The microbial community in leaf litter responded to nitrogen addition with increased phylogenetic clustering (higher OTU richness and NRI), which suggests that environmental filtering exerted a homogenizing selective pressure linked to both soil and litter properties, whereas the microbial community in branch litter responded to nitrogen addition with increased taxonomic diversity (higher OTU richness, Shannon, ACE, and Chao1), a pattern associated with litter properties that likely alleviated nitrogen limitation and created opportunities for more taxa to coexist. The observed differences in response stem from distinct substrate properties of the litter. This study elucidates microbial taxonomic and phylogenetic diversity responses to nitrogen addition during litter decomposition, offering a scientific foundation for precise microbial community regulation and sustainable litter management. Full article

The effects of wildfires and prescribed burnings on soil are highly variable. In order to evaluate the effects of different burning intensities on soil properties, a surface-controlled burn of undisturbed soil monoliths was carried out by combining temperatures (50 and 80 °C) and residence times (12 and 24 min). The effects of this burning gradient are evaluated at two soil depths (0–1 and 1–3 cm), with time (just after burning or immediate effects, T0, and five months later, T5), as well as the influence of ash (presence or absence). The results indicate that most soil properties were affected by the burning gradient applied only in the most superficial cm (0–1 cm), with few effects at greater depths. The most intense burn had the strongest immediate impact, reducing soil organic carbon, recalcitrant organic carbon, and microbial biomass carbon, as well as increasing the labile organic carbon and the microbial activity. On the other hand, this burning caused a strong decrease in soil water repellency at a 0–1 cm depth and increased it at 1–3 cm. In contrast, medium-intensity burning caused the opposite effect, increasing water repellency at the soil surface and reducing it at 1–3 cm. As a result of the mineralization of organic matter, the EC and pH increased significantly in all burning combinations and both soil depths studied. After five months (T5), several of these parameters tended to approach the values of unburned soil. Full article

Lignocellulosic biomass like pistachio shells (PSs) is a promising feedstock for anaerobic digestion (AD), but lignin recalcitrance limits biodegradability. Conventional pretreatments suffer from high energy costs or inhibitor formation; here, potassium ferrate (PF) + low-thermal pretreatment offers a green alternative. A Box–Behnken Design was employed to optimize the PF dosage, pretreatment temperature, and time, with response variables including the methane (CH₄) yield, soluble chemical oxygen demand (SCOD)/total chemical oxygen demand (TCOD) ratio, and lignin removal efficiency. The optimized conditions (0.637 mmol/g total solids PF dose, 66.76 °C, 55.84 min) achieved a CH₄ yield of 171.00 mL CH₄/g volatile solids, representing a 4.3-fold increase compared to untreated PSs. The ANOVA results showed strong links between how much lignin was removed, the ratio of SCOD to TCOD, and the amount of CH₄ produced, with the interactions between temperature and time being the most important. This study highlights the potential of PF-based pretreatment as a cost-effective and environmentally sustainable strategy to maximize CH₄ yields from lignocellulosic waste, supporting renewable energy adoption and circular economy principles. Further studies should explore scalability and economic feasibility for industrial applications. Full article