Search Results (72)

Hydrothermal liquefaction (HTL) is a promising route for converting wet biomass into bio-oil, but isolated model-component results do not necessarily describe naturally integrated lignocellulosic matrices. Here, lignin, cellulose, and hemicellulose were examined under subcritical HTL conditions (240–320 °C, 5–60 min, and water-to-biomass ratios of 2:1–20:1), and peanut shell and bamboo were used as two representative real feedstocks. At 300 °C and 30 min, lignin gave the highest bio-oil yield (45.36 wt%) and an oil enriched in phenolic compounds (>80% relative GC-MS peak area), whereas cellulose and hemicellulose gave lower oil yields (23.00 and 13.06 wt%, respectively) and larger aqueous-phase fractions. Oil-phase carbon and energy recoveries followed the order lignin (48.2% and 50.5%) > cellulose (32.4% and 35.9%) > hemicellulose (17.7% and 19.2%). A weighted additive reference constructed from the independent model-component results underpredicted phenolics and overpredicted carbohydrate-derived oxygenates in the real-biomass oils. For peanut shell and bamboo, the measured phenolic fractions were 68.85% and 64.11%, compared with additive-reference values of 47.66% and 34.17%, while the measured furanic fractions were 1.27% and 9.76%, compared with 12.12% and 17.88%. These directionally consistent deviations indicate non-additive product redistribution in the tested real-biomass samples. Full article

Bio-waste (i.e., peels), the by-products obtained from the processing of fruits and vegetables, represents an outstanding advance in agricultural waste valorization due to phytochemical (bioactive compounds) enrichment and the approach to a bio-circular economy and agronomic systems free of hazardous pesticides (soil remediation). These alternatives, which are environmentally friendly and sustainable, are greatly relevant to food and nutraceuticals based on bioactive compounds extracted mostly from peels. Bioactive compounds are defined as natural chemical compounds that have a positive influence on human health. They can aid in the prevention of chronic disease (cancer and degenerative, intestinal bowel and cardiovascular disease) and other types of disease. The bioactive compounds with these properties belong to the family of polyphenol compounds, which include flavonoids (i.e., flavones, flavanones, and anthocyanins), non-flavonoids (phenolic acids, stilbenes, lignin, coumarins, and tannins), and terpenes (carotenoids, lycopene, phytosterols, and monoterpenes). The extraction of these compounds from the peels of fruits and vegetables has gained increasing interest as a sustainable technology because of the use of safety solvents. Another important issue to highlight is the enormous potential of bioactive compounds, as mentioned above, in the biotechnology of these compounds, particularly in terms of the development of a delivery system targeting the site of action. Full article

Agricultural expansion and intensification generally lead to a depletion in soil organic carbon (SOC). While converting cropland to grassland is a recognized strategy for SOC accumulation, the patterns of SOC accumulation under different grassland types and soil conditions remain unclear. This study evaluated the long-term effects of two perennial grasses—alfalfa (a legume) and switchgrass (a non-legume)—on SOC composition, specifically lignin phenols and amino sugars, in non-saline and saline–alkali soils, using a conventional wheat–maize rotation as a control. Our results showed that both alfalfa and switchgrass significantly enhanced SOC content compared to a wheat–maize rotation, but their accumulation pathways differed between non-saline and saline–alkali soils. In non-saline soils, increases in both lignin phenols and amino sugars (muramic acid and glucosamine) were observed under both perennial grasses. In saline–alkali soils, however, the accumulation was primarily driven by glucosamine. While no significant difference was observed in amino sugars content between the two grasses, switchgrass showed significantly higher lignin phenols content than alfalfa under saline–alkali conditions. This indicated that litter quality regulated the accumulation of plant-derived C in saline–alkali environments, but has no significant impact on the accumulation of microbial-derived C. These findings elucidate the divergent mechanisms that drive SOC sequestration following cropland-to-grassland conversion in contrasting non-saline and saline–alkali soils, highlight the dominant role of microbial processes in SOC accumulation following such conversion. Full article

The transition towards sustainable biofuels requires innovative strategies to maximize the utilization of agroindustrial biomass. Accordingly, the aim of this study was to evaluate avocado stone biomass as a renewable substrate for producing glucose and bioethanol, and to characterize potential co-products from the pretreatment stream, including avocado phenolic compounds. It was found that the whole avocado stone and the seed contained 41.7% and 42.8% of starch, respectively, accounting for more than 78% of the glucans. Using microwave-diluted acid pretreatment and multi-response optimization, a direct conversion of ~90% of glucans to glucose was achieved from avocado stone biomass at 1% w/v sulfuric acid, 140 °C, and 5 min. It also enabled minimizing inhibitor presence and reducing energy requirements. Then, the glucose-rich hydrolyzate was efficiently fermented into bioethanol (~24 g/L in 12 h) using Saccharomyces cerevisiae, without needing detoxification or enzyme addition. Additionally, the process yielded a lignin-rich solid fraction with an enhanced higher heating value (about 1.4 times) compared to the original biomass and an extract with phenolic compounds like caffeoylquinic acids and hydroxytyrosol, which enhances the valorization potential of this underutilized biomass. The overall balance can be 240 kg/t of bioethanol, along with 2.5 kg/t of phenolic compounds and 376 kg/t of lignin-rich solid. Finally, this work exemplified, in a real-world scenario, how we can fully leverage these often-overlooked, non-edible sources of starch to achieve the green transition and circularity. Full article

Air pollution acts as a pervasive oxidative stressor, disrupting global crop production and ecosystem health through the overproduction of reactive oxygen species (ROS). Hazardous pollutants impair critical physiological processes—photosynthesis, respiration, and nutrient uptake—triggering oxidative damage and yield losses. This review synthesizes current knowledge on plant defense mechanisms, emphasizing the integration of enzymatic (SOD, POD, CAT, APX, GPX, GR) and non-enzymatic (polyphenols, glutathione, ascorbate, phytochelatins) antioxidant systems to scavenge ROS and maintain redox homeostasis. We highlight the pivotal roles of transcription factors (MYB, WRKY, NAC) in orchestrating stress-responsive gene networks, alongside MAPK and phytohormone signaling (salicylic acid, jasmonic acid, ethylene), in mitigating oxidative stress. Secondary metabolites (flavonoids, lignin, terpenoids) are examined as biochemical shields against ROS and pollutant toxicity, with evidence from transcriptomic and metabolomic studies revealing their biosynthetic regulation. Furthermore, we explore biotechnological strategies to enhance antioxidant capacity, including overexpression of ROS-scavenging genes (e.g., TaCAT3) and engineering of phenolic pathways. By addressing gaps in understanding combined stress responses, this review provides a roadmap for developing resilient crops through antioxidant-focused interventions, ensuring sustainability in polluted environments. Full article

Colletotrichum capsici is an important pathogen causing anthracnose in postharvest peppers in parts of Asia, seriously compromising quality and storage life. Unveiling the pathogenic mechanism can better prevent postharvest disease in pepper. This study investigated the impacts of C. capsici infection on cell wall and phenylpropanoid metabolism in postharvest pepper. Compared to the non-inoculated peppers, C. capsici infection notably increased the disease index, damaged visual quality, and reduced the firmness. Morphological observations showed that C. capsici infection contributed to the collapse of epidermal cell structure. During the early stage, C. capsici triggered pepper’s defensive responses, including lignin deposition around the wounds, increased cellulose and hemicellulose content, and boosted disease-resistance enzymes, including phenylalanine ammonia-lyase (PAL), cinnamic acid 4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), laccase (LAC), β-1,3-glucanase (β-1,3-Glu), and chitinase (CHI), alongside elevated total phenolics and flavonoids. However, as storage time progressed, the activities of carboxymethy cellulase (Cx), polygalacturonase (PG), pectin methylesterase (PME), and β-glucosidase (β-Glu) remained at a high level, leading to a reduction in cell wall components, a decline in the activities of disease-resistance enzymes, and a decrease in phenylpropanoid metabolite, resulting from disease progression in pepper. These insights highlight the need for early intervention strategies to mitigate postharvest losses by targeting pathogen-induced stress responses and cell wall integrity preservation. Full article

Cabbage (Brassica oleracea L.) is a globally significant vegetable crop that faces productivity challenges due to fungal and bacterial pathogens. This review highlights the potential of spectral imaging techniques, specifically multispectral and hyperspectral methods, in detecting biotic stress in cabbage, with a particular emphasis on pathogen-induced responses. These non-invasive approaches enable real-time assessment of plant physiological and biochemical changes, providing detailed spectral data to identify pathogens before visible symptoms appear. Hyperspectral imaging, with its high spectral resolution, allows for distinctions among different pathogens and the evaluation of stress responses, whereas multispectral imaging offers broad-scale monitoring suitable for field-level applications. The work synthesizes research in the existing literature while presenting novel experimental findings that validate and extend current knowledge. Significant spectral changes are reported in cabbage leaves infected by Alternaria brassicae and Botrytis cinerea. Early-stage detection was facilitated by alterations in flavonoids (400–450 nm), chlorophyll (430–450, 680–700 nm), carotenoids (470–520 nm), xanthophyll (520–600 nm), anthocyanin (550–560 nm, 700–710 nm, 780–790 nm), phenols/mycotoxins (700–750 nm, 718–722), water/pigments content (800–900 nm), and polyphenols/lignin (900–1000). The findings underscore the importance of targeting specific spectral ranges for early pathogen detection. By integrating these techniques with machine learning, this research demonstrates their applicability in advancing precision agriculture, improving disease management, and promoting sustainable production systems. Full article

Wood adhesives play a critical role in the wood processing industry; however, traditional formaldehyde-based adhesives pose health risks and are reliant on non-renewable resources. This study aims to develop a bio-based wood adhesive with excellent water resistance, focusing on environmentally friendly solutions. The synthesis of an oxidized starch-lignin (OSTL) composite adhesive was accomplished by modifying starch via oxidation and subsequent cross-linking with lignin. Ammonium persulfate (APS) was employed for oxidation of starch, introducing aldehyde groups that upgrade its reactivity with lignin. Subsequently, the oxidized starch (OST) was cross-linked with the phenolic rings of lignin, resulting in a strong network structure. The oxidation of starch and its cross-linking mechanism with lignin were investigated using the Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H-NMR), and X-ray photoelectron spectroscopy (XPS) techniques, proving the formation of aldehyde and carboxyl groups with subsequent reaction possibilities. The effects of oxidant dosage, oxidation time, and the ratio of starch to lignin on the adhesive properties were systematically studied. The results demonstrated that the OSTL adhesive, prepared under optimized conditions, exhibited outstanding adhesion strength (1.23 MPa in dry state) and water resistance (0.94 MPa after 24 h cold water immersion, 1.04 MPa after 3 h in hot water, and 0.69 MPa after 3 h in boiling water), significantly outperforming conventional wood adhesives in terms of cold water, hot water, and boiling water resistance. In addition, the thermal behavior of the OSTL adhesive was further validated using differential scanning calorimetry (DSC) as well as thermogravimetric analysis (TGA). This study presents new insights and technical support for the development of green, environmentally friendly, and highly water-resistant lignin-based bio-adhesives. Full article

Single-ring aromatic compounds including BTX (benzene, toluene, xylene) serve as essential building blocks for high-performance fuels and specialty chemicals, with extensive applications spanning polymer synthesis, pharmaceutical manufacturing, and aviation fuel formulation. Current industrial production predominantly relies on non-renewable petrochemical feedstocks, posing the dual challenges of resource depletion and environmental sustainability. The catalytic hydrodeoxygenation (HDO) of lignin-derived phenolic substrates emerges as a technologically viable pathway for sustainable aromatic hydrocarbon synthesis, offering critical opportunities for lignin valorization and biorefinery advancement. This article reviews the relevant research on the conversion of lignin-derived phenolic compounds’ HDO to benzene and aromatic hydrocarbons, systematically categorizing and summarizing the different types of catalysts and their reaction mechanisms. Furthermore, we propose a strategic framework addressing current technical bottlenecks, highlighting the necessity for the synergistic development of robust heterogeneous catalysts with tailored active sites and energy-efficient process engineering to achieve scalable biomass conversion systems. Full article

Considerable amounts of agro-industrial by-products are discarded every year. Moreover, these represent an interesting source of phenolics, cellulose and lignin, in addition to useful compounds such as antioxidants. However, these compounds may be affected by external factors such as genotype, locality and productive season, increasing or decreasing the antioxidant potential of by-products. In this study, hazelnut (Corylus avellana L.) and walnut (Juglans regia L.) nutshells were investigated for their fiber content and antioxidant capacity as valorized by-products in this industry. The determination of oxygen radical absorbance capacity (ORAC), total phenolic content (TPC) and color difference was performed using hazelnut and walnut shells collected from orchards located in Southern Chile during three consecutive seasons (2020/21, 2021/22 and 2022/23). The ORAC in nutshells showed the highest values in both species for the season 2020/21 (3217 and 4663 µmol TE g DW⁻¹ for hazelnut and walnut), whereas the variability in consecutive seasons was lower for hazelnut than for walnut. The TPC in hazelnut shells was positively correlated with L* (R: 0.883) and ΔE (r = 0.924) during the 2020/21 season and with L* for 2022/23 (r = 0.907). On the other hand, the ORAC was negatively correlated with L* (r = 0.922) in 2021/22. In addition, the morphological and structural features of both nutshells examined by scavenging electron microscopy (VP-SEM) and confocal scavenging laser microscopy (CSLM) revealed differential tissue distribution and accumulation patterns of both cellulose and lignin. In addition, photo-colorimetric values were determined for both shells and corresponding seasons, and non-significant differences were found for both shells and among seasons. Finally, our results provide new insights into the physicochemical characteristics of these two types of nutshells as valorized by-products, considering their antioxidant properties as residual materials derived from this agroindustry. Full article

Flax (Linum usitatissimum L.) is a plant of high economic and practical importance valued for its fiber and oil, which have diverse applications in industries such as textiles, food, pharmaceuticals, and construction. Fungal pathogens of the genus Fusarium, however, pose one of the most serious threats to flax cultivation. They are responsible for a number of disease manifestations, notably Fusarium wilt and root rot. In the case of fusariosis, there is a lack of plant protection products, and often the only effective approach is to use resistant flax cultivars or to discontinue cultivation for several years. Currently, much attention is paid to biological methods of plant protection, which do not exert a negative influence on the environment or human health and are important for sustainable agriculture. The aim of the present study was to assess the potential of the non-pathogenic endophytic fungal strain Fusarium oxysporum Fo47 in protecting plants against pathogenic fungi. The results showed that pretreatment of flax plants with Fo47 increased resistance of plants to all tested fungi (F. oxysporum, Fusarium culmorum, Rhizoctonia solani). Fo47 was the most effective for protection against F. culmorum for the Jan flax cultivar and R. solani for the Bukoz cultivar. Pretreatment with Fo47 of flax plants inoculated with F. culmorum caused an increase in the level of secondary metabolites involved in plant resistance (phenolics) and photosynthetic pigments (chlorophyll a and b) compared to plants treated only with the pathogenic fungal strain. Fourier transform infrared spectroscopy revealed structural changes in the polymers of cell walls. The highest intensities of vibrations characteristic of lignin and pectin were observed for flax treated with Fo47 and infected with F. culmorum, suggesting the highest level of these polymers, higher than in plants treated only with pathogenic fungi. Thus, it can be concluded that application of the non-pathogenic strain strengthened the immune response of flax plants. These results highlight the strong potential of the non-pathogenic strain as a biological control agent, especially for Fusarium infection in flax. Full article

The value-added effect of white rot fungi on the feed of Astragalus membranaceus var. mongholicus (AMM) stems was explored. All four types of white rot fungi (Lentinus sajor-caju, Pleurotus ostreatus, Lentinula edodes, and Phanerodontia chrysosporium) reduced the lignocellulose content in AMM stems, improved in vitro dry matter digestibility (IVDMD), and influenced the activity of lignocellulose-degrading enzymes. Lentinus sajor-caju and Phanerodontia chrysosporium exhibited superior effects on lignin degradation and IVDMD and significantly altered non-volatile metabolites and antioxidant capacity. Lentinus sajor-caju fermentation resulted in the strongest antioxidant activity compared to that in the other fungal treatments. The fold change (FC) ratio (>100) of sakuranetin, 2′,6′-Di-O-acetylononin, isoformononetin, and artocarpin was compared between Lentinus sajor-caju and Phanerodontia chrysosporium. Among the phenolic compounds, flavonoids play a key role in antioxidant activity, with 5,6-Dihydroxy-7-methoxyflavone showing a strong correlation with antioxidant activity. This study provides valuable insights for utilizing AMM stem waste in the context of traditional Chinese medicine. Full article

Objective: Laccases are known to be able to degrade phenolic compounds to simpler components. The main objective of our study was to analyze this property in transgenic aspen plants carrying the laccase gene Lac from Trametes hirsuta which can be potentially used in soil phytoremediation. Methods: We created transgenic aspen plants carrying the laccase gene Lac from Trametes hirsute using the agrobacterial transformation of stem explants with the pBI–Lac vector containing the Lac gene from the white rot fungus T. hirsuta 072 (NCBI GenBank accession number KP027478). Transgenic plants were micropropagated and cultivated in vitro in lines. The degradation of 2,4,6-trichlorophenol (2,4,6-TCP) by plant roots was analyzed by mass-spectrometry with electron ionization using a gas chromatograph. Results: Although plants have their own laccases, those of fungal origin are more effective. All transgenic plants that expressed the recombinant gene degraded 2,4,6-TCP more effectively than non-transformed plants in the control (the degradation efficiency ranged 92 to 98% versus 82% in non-transformed control). Line 47Lac8 demonstrated a 16% higher efficiency than the non-transformed plants in the control. There was also an inverse relationship between the viability of a transgenic line and its level of expression of the recombinant gene. Thus, line 47Lac4 was not viable under native conditions, probably due to lignin synthesis disruptions during the initiation of secondary tissues. This is confirmed by changes in the expression of native genes of lignin biosynthesis. The rest of the transgenic lines did not differ significantly from control in wood growth and biochemistry. The transgenic plant roots were shown to preserve the ability to express the Lac gene ex vitro. Conclusions: Three transgenic lines (47Lac5, 47Lac8, and 47Lac23) with the Lac gene can be recommended for use in soil phytoremediation. Full article

The most important ligninolytic enzymes in lignin degradation include laccases and peroxidases (lignin peroxidase, manganese peroxidase, versatile peroxidase). White-rot fungi (e.g., Cerrena sp., Phlebia sp. or Trametes sp.) are their main source in nature. The ability of ligninolytic enzymes to degrade both phenolic and non-phenolic compounds has found its application in sustainable agriculture. In recent years, ligninolytic enzymes’ important role has been demonstrated in the biodegradation of lignin, a poorly degradable component of plant biomass, and in removing hazardous environmental pollutants that threaten human health. These enzymes can be successfully used in waste management, composting, improving soil health and fertility, or bioremediation. The challenges of applying lignin-degrading enzymes such as laccases and peroxidases include their stability and resistance to harsh conditions. Still, the rapid development of biotechnological technologies offers the tools to overcome them. Applying biological solutions in agricultural systems involving microorganisms and their metabolic products will significantly reduce the environmental impact and develop a circular economy. Full article

Ni phytotoxicity has been attributed to its multidirectional detrimental effects on plant cell structure and function. However, relatively little is known about Ni’s impact on phenolic metabolism in plants. The objective of our study was to obtain insight into the effect of Ni treatment on phenolic compound composition, phenol-related enzyme activities, and lignin accumulation in cucumber plants. Besides growth reduction, the chlorophyll a and carotenoid contents as well as the chlorophyll a fluorescence parameters, namely, the maximum photochemical efficiency of PS II and non-photochemical quenching, were significantly decreased in the Ni-treated cucumber plants. Application of Ni resulted in changes in the phenolic acid and flavonoid profiles; however, the total content of the detected phenolic compounds remained unchanged in the leaf and slightly decreased in the root. The Ni-induced release of free phenolic acids from their conjugates was found in the leaf. Ni treatment led to a marked increase in leaf peroxidase activities assayed with various phenolic substrates, while it did not influence phenyl ammonia lyase and polyphenol oxidase activities. Increased lignin deposition was observed in the leaf blade of Ni-exposed plants. Neither lignin accumulation nor induction of peroxidase activities were found in the root. Our results indicate that the Ni effect on phenolic compound composition and related enzyme activities is organ-specific. The observed changes in the content of individual compounds might result rather from the metal-triggered conversions of the compounds constitutively present in the cucumber tissues than from de novo synthesis. Full article