Search Results (78)

Microbial fermentation stands as the foundational technology in modern biorefineries, yet its industrial scalability is critically constrained by product inhibition, prohibitive downstream separation costs, and substrate inhibition. Metal–organic frameworks (MOFs) offer a tunable material platform to address these challenges through rational design of pore size, shape, and chemical functionality. This review systematically chronicles the evolution of MOF applications in biomass fermentation across four generations, demonstrating a synergistic mapping where the core fermentation challenges—product toxicity, substrate toxicity, and separation energy intensity—align with the inherent MOF advantages of high adsorption capacity, programmable selectivity, and tunable functionality. The applications progress from first-generation passive adsorbents for in situ product removal, to second-generation protective agents for mitigating inhibitors, and third-generation immobilization scaffolds enabling continuous processing. The fourth-generation systems transcend passive scaffolding to position MOFs as active metabolic partners in microbe-MOF hybrids, driving cofactor regeneration and tandem biocatalysis. By synthesizing diverse research streams, ranging from defect engineering to artificial symbiosis, including defect engineering strategies, this review establishes critical design principles for the rational integration of programmable materials in next-generation biorefineries. Full article

Agro-industrial chestnut waste derived from chestnut processing is usually discharged without further use. However, these residues are attractive due to their high-value composition, rich in sugars and lignin. Among these residues, chestnut burrs (CB) represent a promising feedstock for biorefinery applications aimed at maximizing the valorization of their main constituents. In this study, we propose an environmentally friendly approach based on deep eutectic solvents (DES) formed by choline chloride and urea (ChCl/U) (1:2, mol/mol) for the selective deconstruction of lignocellulosic architecture, followed by enzymatic hydrolysis to release second-generation (2G) fermentable sugars. Pretreatments were applied to raw CB, washed CB (W-CB), and the obtained solid fraction after prehydrolysis (PreH). Structural and morphological modifications, as well as crystallinity induced by DES pretreatment, were characterized using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). Remarkable results in terms of effectiveness and environmental friendliness on saccharification yields were achieved for PreH subjected to DES treatment for 8 h, reaching approximately 60% glucan and 74% xylan conversion under the lower enzyme loading (23 FPU/g) and liquid-to-solid ratio (LSR) of 20:1 studied. This performance significantly reduces DES pretreatment time from 16 h to 8 h at mild conditions (100 °C), lowers the LSR for enzymatic hydrolysis from 30:1 to 20:1, and decreases enzyme loading from 63.5 FPU/g to 23 FPU/g, therefore improving process efficiency and sustainability. Full article

Lignin is the most structurally complex component of lignocellulosic biomass. Each year, thousands of tons of lignin-rich residues from enzymatic hydrolysis are generated in sugarcane-based cellulosic ethanol biorefineries. The current study specifically utilizes lignin extracted from sugarcane bagasse as the primary feedstock for biochar production, rather than employing the raw bagasse itself. This study investigates, through pyrolytic thermal treatment of two lignin sources, the production of biochars and the evaluation of their potential applications. Kraft commercial lignin and sugarcane bagasse lignin samples, along with their corresponding biochars, were characterized by elemental and proximate analyses, higher heating value determination, spectroscopic techniques, thermogravimetric analysis, X-Ray diffraction, scanning electron microscopy coupled with energy-dispersive spectroscopy, and true density measurements. The results revealed a lower contamination level associated with the extraction process and confirmed the amorphous nature of sugarcane bagasse lignin and its derived biochar. An O/C ratio of approximately 0.3 was obtained for the sugarcane bagasse lignin biochar based on both elemental and Raman spectroscopy analyses. Both elemental composition assessment and Raman spectroscopic analysis indicated that all biochar specimens exhibited hydrogen-to-carbon (H/C) ratios exceeding 0.5. The analyses, therefore, indicated that the biochar derived from sugarcane lignin exhibited higher energy density, moderate stability and a high carbon content. The proposed approach thus provides promising alternatives for the valorizing lignin residues derived from second-generation ethanol production processes. Full article

Brewer’s spent grain (BSG), the main lignocellulosic by-product of the beer industry, represents an abundant yet underutilized resource with high potential for valorization. This study presents an integrated biorefinery approach to convert BSG into second-generation (2G) ethanol, bioactive vinasse for plant growth promotion, and fungal biomass as a potential mycoprotein source. The biomass was first subjected to biological delignification using the white-rot fungus Ganoderma lucidum, after which two valorization routes were explored: (i) evaluation of the fungal biomass as a mycoprotein candidate and (ii) alcoholic fermentation for ethanol production. For the latter, three pretreatment strategies were assessed (diluted sulfuric acid and two deep eutectic solvents (DESs) based on choline chloride combined with either glycerol or lactic acid) followed by a one-pot enzymatic saccharification and fermentation using Kluyveromyces marxianus SLP1. The highest ethanol yield on substrate (Y_P/S) was achieved with [Ch]Cl:lactic acid pretreatment (0.46 g/g, 89.32% of theoretical). Vinasse, recovered after distillation, was characterized for organic acid content and tested on Solanum lycopersicum seed germination, showing promising biostimulant activity. Overall, this work highlights the potential of BSG as a sustainable feedstock within circular economy models, enabling the production of multiple bio-based products from a single residue. Full article

Native yeasts are a promising microbial resource for the development of sustainable biorefineries. In this study, we isolated 30 yeast strains from soil, decaying wood, and tree bark in a preserved Araucaria Forest in Southern Brazil and characterized them phenotypically and taxonomically. All strains were able to grow on glucose, xylose, and cellobiose, and 50% of them could metabolize arabinose. Several isolates showed high growth rates on xylose (up to 0.47 h⁻¹) and cellobiose (up to 0.45 h⁻¹). Notably, 19 strains (63% of the analyzed yeasts) exhibited xylanase activity at 50 °C (up to 156.84 U/mL), and four strains (13%) showed significant cellulase production. β-Glucosidase activities were particularly high in permeabilized cells of CHAP-258, CHAP-277, and CHAP-278 (up to 584.33 U/mg DCW), with kinetic parameters indicating high enzymatic performance. Twelve strains (40% of the total) were classified as oleaginous, and three (10%) displayed both lipogenic and esterase activity. Lipase activity against p-nitrophenyl palmitate (pNPP) reached 55.55 U/mL in CHAP-260. Taxonomic identification revealed representatives of seven genera, including Meyerozyma, Papiliotrema, Scheffersomyces, and Sugiyamaella, with potential for biotechnological use. Overall, the biochemical diversity observed highlights the value of native yeasts from Araucaria Forests as biocatalysts for lignocellulose-based bioprocesses, particularly due to their ability to grow on pentoses, secrete hydrolytic enzymes, and accumulate lipids. Full article

Developing efficient, clean, and sustainable lignocellulose pretreatment technologies is essential for second-generation biofuel production. In this study, we attempted to use downstream-separated binary acetone-water, n-butanol-water, and ethanol-water solutions as the initial liquor for upstream organosolv pulping, in order to achieve the efficient and economic closed-circuit clean fractionation of the lignocelluloses for biological acetone–butanol–ethanol (ABE) production. Parameters, including concentration and temperature of the organosolv pulping, were optimized systematically. Results indicated that the 50 wt% ethanol and 30 wt% acetone aqueous solutions and pulping at 200 °C for 1 h exhibited better corn stover fractionation performances with higher fermentable sugar production. The total monosaccharide recovery (including glucose and xylose) was 50.92% and 50.89%, respectively, in subsequent enzymatic saccharification. While pulping corn stover using n-butanol solution as initial liquor showed higher delignification 86.16% (50 wt% of n-butanol and 200 °C for 1 h), the hydrolysate obtained by the organosolv pulps always exhibited good fermentability. A maximized 15.0 g/L of ABE with 0.36 g/g of yield was obtained in Ethanol-200 °C-50% group, corresponding to 112 g of ABE production from 1 kg of raw corn stover. As expected, the lignin specimens fractionated by closed-circuit organosolv pulping exhibited narrow molecule weight distribution, high purity, and high preservation of active groups, which supports further valorization. This novel strategy tightly bridges the upstream and downstream processes of second-generation ABE production, providing a new route for ‘energy-matter intensive’ and environmentally friendly lignocelluloses biorefineries. Full article

Fungal lytic polysaccharide monooxygenases (LPMOs) have revolutionized the field of biomass degradation by introducing an oxidative mechanism that complements traditional hydrolytic enzymes. These copper-dependent enzymes catalyze the cleavage of glycosidic bonds in recalcitrant polysaccharides such as cellulose, hemicellulose, and chitin, through the activation of molecular oxygen (O₂) or hydrogen peroxide (H₂O₂). Their catalytic versatility is intricately modulated by structural features, including the histidine brace active site, surface-binding loops, and, in some cases, appended carbohydrate-binding modules (CBMs). The oxidation pattern, whether at the C1, C4, or both positions, is dictated by subtle variations in loop architecture, amino acid microenvironments, and substrate interactions. LPMOs are embedded in a highly synergistic fungal enzymatic system, working alongside cellulases, hemicellulases, lignin-modifying enzymes, and oxidoreductases to enable efficient lignocellulose decomposition. Industrial applications of fungal LPMOs are rapidly expanding, with key roles in second-generation biofuels, biorefineries, textile processing, food and feed industries, and the development of sustainable biomaterials. Recent advances in genome mining, protein engineering, and heterologous expression are accelerating the discovery of novel LPMOs with improved functionalities. Understanding the balance between O₂- and H₂O₂-driven mechanisms remains critical for optimizing their catalytic efficiency while mitigating oxidative inactivation. As the demand for sustainable biotechnological solutions grows, this narrative review highlights how fungal LPMOs function as indispensable biocatalysts for the future of the Circular Bioeconomy and green industrial processes. Full article

Creole avocado is the second most widely produced and consumed variety of avocado globally. Due to its commercialization, limited studies have explored its potential for sustainable applications in biorefinery, particularly focusing on reusing the significant amount of waste generated during its consumption. This research evaluates thermodynamic energy losses of a Creole avocado extractive-based biorefinery, which are of critical importance during the fruit valorization process to determine the efficiency and possibilities of optimization, as well as sustainability impacts, through an exergy balance using computer-aided process engineering. The proposed method utilizes the whole fruit to produce three primary bioproducts, with a focus on implementation in the Montes de María region of Colombia. Following the extended mass and energy balance, an in-depth exergetic analysis was conducted, revealing that all process stages exhibited an exergetic efficiency exceeding 50%. The irreversibilities of the process were calculated as 7763.74 MJ/h, the total waste exergy was 2924.42 MJ/h, and the exergy from industrial waste amounted to 7800.42 MJ/h. These findings highlight the potential for optimizing the sustainability of avocado-based production systems through computer-aided analysis as an effective method. This approach accurately identifies exergy losses at each stage, providing precise numerical data and graphical representations. Additionally, it underscores not only the environmental benefits but also the contribution of these systems to enhancing energy efficiency in agro-industrial applications. Full article

Based on Life Cycle Assessment (LCA) and ISO standards, we compared the global environmental sustainability (ES) of two technologies that process the organic fraction of municipal solid waste (OFMSW) in Mexico. The first technology was a biorefinery (BRF) known as HMEZSNN-BRF (abbreviation for Hydrogen-Methane-Extraction-Enzyme-Saccharification/Nanoproduction Biorefinery); it produces the gas biofuels hydrogen (H) and methane (M), organic acids (E), enzymes (Z), saccharified liquors (S), and bionanobioparticles (BNBPs) in a nanoproduction stage (NN). The second technology was incineration with energy recovery (IER). An LCA was performed with a functional unit (FU) of 1000 kg of OFMSW. The BRF generates 166.4 kWh/FU (600 MJ) of net electricity, along with bioproducts such as volatile organic acids (38 kg), industrial enzyme solution (1087 kg), and BNBPs (40 kg). The IER only produces 393 net kWh/FU electricity and 5653 MJ/FU heat. The characterization potential environmental impacts (PEIs) were assessed using SimaPro software, and normalized PEIs (NPEIs) were calculated accordingly. We defined a new variable alpha and the indices σ-τ plane for quantifying the ES. The higher the alpha, the lower the ES. Alpha was the sum of the eighteen NPEIs aligned with the ISO standards. The contributions to PEI and NPEI were also analyzed. Four NPEIs were the highest in both technologies, i.e., freshwater and marine ecotoxicities and human non-carcinogenic and carcinogenic toxicities. For the three first categories, the NPEI values corresponding to IER were much higher than those of the BRF (58.6 and 8.7 person*year/FU freshwater toxicity; 93.5 and 13.6 marine ecotoxicity; 12.1 and 1.8 human non-carcinogenic toxicity; 13.7 and 13.9 human carcinogenic toxicity, for IER and the BRF, respectively). The total α values were 179.1 and 40.7 (person*yr)/FU for IER and the BRF, respectively. Thus, the ES of IER was four times lower than that of the BRF. Values of σ = 0.592 and τ = −0.368 were found; the point defined by these coordinates in the σ-τ plane was located in Quadrant IV. This result confirmed that the BRF in this work is more environmentally sustainable (with restrictions) than the IER in Mexico for the treatment of the OFMSW. Full article

The valorization of agri-food wastes can provide value-added products, enzymes and biofuels. For the second-generation ethanol (2G) production, pulps rich in cellulose are desirable in order to release fermentable sugars. This study investigated the homemade biosynthesis of cellulases and hemicellulases via solid-state fermentation (SSF) using sugarcane bagasse (SB) and wheat bran (WB) for the growth of endophytic fungi (Beauveria bassiana, Trichoderma asperellum, Metarhizium anisopliae and Pochonia chlamydosporia). Cocktails with high enzymatic levels were obtained, with an emphasis for M. anisopliae in the production of β-glucosidase (83.61 U/g after 288 h) and T. asperellum for xylanase (785.50 U/g after 144 h). This novel M. anisopliae β-glucosidase demonstrated acidophile and thermotolerant properties (optimum activity at pH 5.5 and 60 °C and stability in a wide pH range and up to 60 °C), which are suitable for lignocellulose saccharifications. Hence, the M. anisopliae multi-enzyme blend was selected for the hydrolysis of raw and organosolv-pretreated corn straw (CS) and corncob (CC) using 100 CBU/g cellulose. After the ethanol/water (1:1) pretreatment, solid fractions rich in cellulose (55.27 in CC and 50.70% in CS) and with low concentrations of hemicellulose and lignin were found. Pretreated CC and CS hydrolysates reached a maximum TRS release of 12.48 and 13.68 g/L, with increments of 100.80 and 73.82% in comparison to untreated biomass, respectively, emphasizing the fundamental role of a pretreatment in bioconversions. This is the first report on β-glucosidase biosynthesis using M. anisopliae and its use in biomass hydrolysis. These findings demonstrated a closed-loop strategy for internal enzyme biosynthesis integrated to reducing sugar release which would be applied for further usage in biorefineries. Full article

India’s rapidly growing automobile industry has intensified the need for sustainable fuel alternatives to reduce dependency on imported fossil fuels and mitigate greenhouse gas (GHG) emissions. This study examines the potential of second-generation biorefineries as a comprehensive solution for efficient biomass valorization in India. With a projected bioethanol demand of 10,160 million liters by 2025 for India’s 20% ethanol blending target, there is an urgent need to develop sustainable production pathways. The biorefinery approach enables simultaneous production of multiple valuable products, including bioethanol, biochemicals, and bioproducts, from the same feedstock, thereby enhancing economic viability through additional revenue streams while minimizing waste. This paper systematically analyzes available biomass resources across India, evaluates integrated conversion technologies (biochemical, thermochemical, and synergistic approaches), and examines current policy frameworks supporting biorefinery implementation. Our findings reveal that second-generation biorefineries can significantly contribute to reducing GHG emissions by up to 2.7% of gross domestic product (GDP) by 2030 while creating rural employment opportunities and strengthening energy security. However, challenges in supply chain logistics, technological optimization, and policy harmonization continue to hinder large-scale commercialization. The paper concludes by proposing strategic interventions to overcome these barriers and accelerate the transition toward a sustainable circular bioeconomy in India. Full article

The increasing demand for renewable energy sources has led to significant interest in second-generation biofuels derived from lignocellulosic biomass and waste materials. This review underscores the pivotal role of lignocellulosic biomass valorization in meeting global energy needs, mitigating greenhouse gas emissions, and fostering a circular bioeconomy. Key pretreatment methods—including steam explosion, pressure treatment, and chemical pretreatment—are analyzed for their ability to enhance the accessibility of cellulose and hemicellulose in enzymatic saccharification. Advances in cellulolytic enzyme development and fermentation strategies, such as the use of genetically engineered microorganisms capable of fermenting both hexoses and pentoses, are discussed in detail. Furthermore, the potential of biorefinery systems is explored, highlighting their capacity to integrate biomass valorization into biofuel production alongside high-value bioproducts. Case studies and recent trends in bioethanol and biogas production are examined, providing insights into the current state of research and its industrial applications. While lignocellulosic biofuels hold considerable promise for sustainable development and emissions reduction, challenges related to cost optimization, process scalability, and technological barriers must be addressed to enable large-scale implementation. This review serves as a comprehensive foundation for bridging the gap between laboratory research and industrial application, emphasizing the need for continued innovation and interdisciplinary collaboration in biofuel technologies. Full article

Natural resources are currently overexploited to provide food supply for the ever-increasing world population, and because of the intensification of agricultural and food production, there is a growing rate of waste generation. This waste biomass is usually dumped into landfills, causing unprecedented damage to ecosystems. Nowadays, circular economy strategies are channeled towards waste harnessing, aiming at reducing the irrational use of resources and minimizing waste generation. Potatoes are the second largest food crop after cereals, and there is an overwhelming amount of waste derived from potato tuber processing, composed almost exclusively of peels. Potato peels (PPs) are considered a source of polyphenolic compounds, largely represented by chlorogenic acid and other structurally related hydroxycinnamates, which possess a spectrum of bioactivities; however, there is a lack of analytical data compilations that could be of assistance in pertinent studies. With this as the conceptual basis, the scope of this review focused on a particular class of polyphenols, the so-called hydroxycinnamates, to deliver compiled data associated with the occurrence, retrieval, and application of this group of compounds derived from potato waste with major emphasis being given to PPs. It is believed that the collection of data of this nature, due to their undisputed significance in studies pertaining to bioeconomy, biorefinery, and food waste valorization, would provide a highly useful contribution to the field. Full article

A biocatalyst has been developed for application in the simultaneous isomerization and fermentation (SIF) of xylose, which could enable operation in repeated batches and the use of xylose from biomass hemicellulose for the production of second-generation (2G) ethanol. To this end, the enzyme xylose isomerase (XI) was immobilized on eleven different supports (based on chitosan, modified silica, agarose and magnetic supports) to obtain a derivative that is stable under process conditions and easy to recover from the fermented medium for future industrial application in biorefineries. Immobilization was performed with 5 mg/g_support, with a support-to-suspension ratio of 1:20. Phosphate (pH 7.0) and carbonate–bicarbonate (pH 10.05) buffer were used for uni-point and multi-point immobilization, respectively. Among the immobilized enzymes, the magnetic microparticle Captura N exhibited the best immobilization parameters (67% recovered activity and half-life of 10 h at 80 °C), in addition to its magnetic properties, which facilitates purification. The SIF of crude sugarcane straw acid hydrolysate was carried out in repeated batches using XI-chitosan and XI-Captura N. Although economically promising, chitosan-based supports did not enhance enzyme stability. Therefore, magnetic microparticles are a promising option as XI immobilization supports for biorefinery applications. Full article

Biorefineries are novel biotechnological routes designed to generate sustainable processes from renewable raw materials. The valorization of orange peel waste (OPW) provides high-value products based on their composition. The economic optimization of biorefineries through conceptual design and generation of superstructures based on the analysis of processing units is a topic of great interest. This work aimed to obtain the most profitable biorefinery through economic optimization strategies based on high-value-added products from OPW. Two stages were considered: The first stage consisted of the conceptual design of multiple OPW processing units (production of essential oil, mucic acid, phenolic compounds, biogas, among others). An OPW flow rate of 140 kg/h was selected as the base case. From the stand-alone units, a biorefinery superstructure (second stage) was designed. Finally, the units with the best mass and energy results were selected in order to maximize the net present value (NPV) and obtain an optimal biorefinery configuration. The results evidenced that the production of essential oil and biogas presented the best yields (2.61 mL and 0.028 m³ per kg OPW, respectively). This biorefinery configuration obtained an NPV of −7.7 mUSD from the base case. Through the evaluation of the different superstructure configurations, the combined production of essential oil, biogas, and mucic acid and a scale-up of over 22 times the base case generated the minimum processing scale. Under a Colombian context, the implementation of the biorefineries analyzed are promising since the minimum processing scale contemplated only 8.8% of the OPW production. Efforts to increase yields and decrease capital and operating expenses while keeping environmental impacts low should be pursued. Full article