Search Results (333)

In recent years, biofuels and bioenergy derived from algae have gained increasing attention, fueled by the growing demand for renewable energy sources and the urgent need to lower CO₂ emissions. This research examines the generation of bioethanol and biomethane using freshly harvested and sedimented algal biomass. Employing a factorial experimental design, various trials were conducted, with ethanol yield as the primary optimization target. The findings indicated that the sodium hydroxide concentration during pretreatment and the amylase dosage in enzymatic hydrolysis were key parameters influencing the ethanol production efficiency. Under optimized conditions—using 0.3 M NaOH, 25 μL/g starch, and 250 μL/g cellulose—fermentation yielded ethanol concentrations as high as 2.75 ± 0.18 g/L (45.13 ± 2.90%), underscoring the significance of both enzyme loading and alkali treatment. Biomethane potential tests on the residues of fermentation revealed reduced methane yields in comparison with the raw algal feedstock, with a peak value of 198.50 ± 25.57 mL/g volatile solids. The integrated process resulted in a total energy recovery of up to 809.58 kWh per tonne of algal biomass, with biomethane accounting for 87.16% of the total energy output. However, the energy recovered from unprocessed biomass alone was nearly double, indicating a trade-off between sequential valorization steps. A comparison between fresh and dried feedstocks also demonstrated marked differences, largely due to variations in moisture content and biomass composition. Overall, this study highlights the promise of integrated algal biomass utilization as a viable and energy-efficient route for sustainable biofuel production. Full article

The transition to sustainable energy sources has intensified interest in lignocellulosic biomass (LCB) as a feedstock for second-generation biofuels. However, the inherent structural recalcitrance of LCB requires the utilization of an effective pretreatment to enhance enzymatic hydrolysis and subsequent fermentation yields. This manuscript presents a novel, single-step, and optimized nitrogen explosive decompression system (NED 3.0) designed to address the critical limitations of earlier NED versions by enabling the in situ removal of inhibitory compounds from biomass slurry and fermentation inefficiency at elevated temperatures, thereby reducing or eliminating the need for post-treatment detoxification. Aspen wood (Populus tremula) was pretreated by NED 3.0 at 200 °C, followed by enzymatic hydrolysis and fermentation. The analytical results confirmed substantial reductions in common fermentation inhibitors, such as acetic acid (up to 2.18 g/100 g dry biomass) and furfural (0.18 g/100 g dry biomass), during early filtrate recovery. Hydrolysate analysis revealed a glucose yield of 26.41 g/100 g dry biomass, corresponding to a hydrolysis efficiency of 41.3%. Fermentation yielded up to 8.05 g ethanol/100 g dry biomass and achieved a fermentation efficiency of 59.8%. Inhibitor concentrations in both hydrolysate and fermentation broth remained within tolerable limits, allowing for effective glucose release and sustained fermentation performance. Compared with earlier NED configurations, the optimized system improved sugar recovery and ethanol production. These findings confirm the operational advantages of NED 3.0, including reduced inhibitory stress, simplified process integration, and chemical-free operation, underscoring its potential for scalability in line with the EU Green Deal for bioethanol production from woody biomass. Full article

Aromatic compounds are vital in both natural and synthetic chemistry, and they are traditionally sourced from non-renewable petrochemicals. However, plant biomass, particularly lignin, offers a renewable alternative source of aromatic compounds. Lignin, a complex polymer found in plant cell walls, is the largest renewable source of aromatic compounds, though its degradation remains challenging. Lignin can be chemically degraded through oxidation, acid hydrolysis or solvolysis. As an alternative, microorganisms, including fungi, could offer a sustainable alternative for breaking down lignin. The aromatic compounds released from lignin, by either microbial, chemical or enzymatic degradation, can be used by microorganisms to produce valuable compounds. Fungi possess unique enzymes capable of converting aromatic compounds derived from lignin or other sources into chemical building blocks that can be used in several industries. However, their aromatic metabolic pathways are poorly studied compared to bacterial systems. In the past, only a handful of genes and enzymes involved in the aromatic metabolic pathways had been identified. Recent advances in genomics, proteomics, and metabolic engineering are helping to reveal these metabolic pathways and identify the involved genes. This review highlights recent progress in understanding fungal aromatic metabolism, focusing on how Aspergillus niger converts plant-derived aromatic compounds into potentially useful products and the versatility of aromatic metabolism within the Aspergillus genus. Addressing the current knowledge gaps in terms of fungal pathways could unlock their potential for use in sustainable technologies, promoting eco-friendly production of chemical building blocks from renewable resources or bioremediation. Full article

This study investigates the structural effects of dilute acid and alkali treatments on cotton fibers, aiming to understand the influence of chemical pretreatment on cellulose morphology. Cotton samples were exposed to 1% sulfuric acid and 1% sodium hydroxide at 90 °C, and the resulting changes were evaluated using scanning electron microscopy and nonlinear optical imaging techniques. The results indicate that sulfuric acid causes significant fiber degradation, leading to fragmentation and reduced fiber thickness. In contrast, sodium hydroxide treatment results in a roughened, flaky surface while preserving the overall structural integrity, with fibers appearing fluffier and more accessible to enzymatic processes. Untreated cotton fibers maintained a smooth and uniform surface, confirming the chemical specificity of the observed changes. These findings are crucial for optimizing biomass pretreatment methods, demonstrating that dilute chemical treatments primarily affect macrostructural features without significantly disrupting the cellulose microfibrils. The study provides valuable insights for the development of efficient biorefining processes and sustainable bio-based materials, highlighting the importance of selecting appropriate chemical conditions to enhance enzymatic hydrolysis and biomass conversion while maintaining the core structure of cellulose. This research contributes to advancing the understanding of cellulose’s structural resilience under mild chemical pretreatment conditions. Full article

This study aims to rapidly in situ identify starch sausage samples with the improper addition of chicken bone paste. Chicken bones play important roles in building materials, biomass fuels, and as food additives after enzymatic hydrolysis, but no current research indicates that chicken bones can be directly added to food for consumption. Especially in starch sausages, the addition of chicken bone paste is highly controversial due to potential risks of esophageal laceration and religious concerns. This paper first uses laser-induced breakdown spectroscopy (LIBS) to investigate the elemental differences between starch sausages and chicken bone paste. By preparing mixtures of starch sausages and chicken bone paste at different ratios, the relationships between the spectral peak intensities of elements, such as Ca, Ba, and Sr, and the proportion of chicken bone paste were determined. Through processing methods such as normalization with reference spectral lines, selection of the signal of the second laser pulse at the same position, and electron temperature correction, the determination coefficients (R²) of each element’s spectral lines have significantly improved. Specifically, the R² values for Ca I, Ca II, Ba II, and Sr II have increased from 0.302, 0.694, 0.857, and 0.691 to 0.972, 0.952, 0.970, and 0.982, respectively. Finally, principal component analysis (PCA) was used to distinguish starch sausages, chicken bone paste, and their mixtures at different ratios, with further effective differentiation achieved through t-distributed stochastic neighbor embedding (t-SNE). The results show that LIBS technology can serve as an effective and rapid method for detecting elemental composition in food and distinguishing different food products, providing safety guarantees for food production and supervision. Full article

This study investigates the optimization of enzymatic hydrolysis for enhancing carbohydrate release from microalgal biomass and its subsequent impact on methane production during anaerobic digestion. Using Response Surface Methodology with a Box–Behnken design comprising 15 experimental runs, the effects of enzyme loading (20–40 mg/gVS), pH (4.5–5.5), and incubation time (24–72 h) were evaluated. A quadratic regression model was developed to predict carbohydrate release, revealing significant interactions between these factors. The optimal conditions for enzymatic hydrolysis were determined to be a cellulase dose of 20 mg/gVS, pH 5.0, and an incubation period of 72 h. The model demonstrated excellent predictive accuracy, with an R² value of 0.9894 and an adjusted R² of 0.9704. Enzymatic hydrolysis significantly improved methane and biogas yields, with cumulative production reaching 52.50 mL/gVS and 95.62 mL/gVS, respectively, compared to 6.98 mL/gVS and 20.94 mL/gVS for untreated samples. The findings highlight the importance of optimizing enzyme loading and reaction time, while pH variations within the studied range had minimal impact. This study underscores the potential of enzymatic hydrolysis to enhance the bioavailability of organic matter, thereby improving the efficiency of anaerobic digestion for biogas production. Full article

This work presents a new approach for lignocellulosic biomass pretreatment. The process is a sequential combination of extrusion (Ex) and semi-solid fermentation (SSF). To assess the Ex-SSF pretreatment efficiency, black spruce chips (wood residues) and corn stover (crop residues) were subjected to the process. The negative controls were the pretreatment of both residues with SSF alone without extrusion. Lignin peroxidase was the main ligninolytic enzyme contributing to the delignification in the negative controls. High lignin peroxide (LiP) activities were recorded for raw black spruce (53.7 ± 2.7 U/L) and corn stover (16.4 ± 0.8 U/L) compared to the Ex-SSF pretreated biomasses where the highest LiP activity recorded was 6.0 ± 0.3 U/L (corn residues). However, with the negative controls, only a maximum of 17% delignification was achieved for both biomasses. As for the Ex-SSF process, the pretreatments were preceded by the optimization of the extrusion (Ex) step and the semi-solid fermentation (SSF) step via experimental designs. The Ex-SSF pretreatments led to interesting results and offered cost-effective advantages compared to existing pretreatments. Biomass delignification reached 59.1% and 65.4% for black spruce and corn stover, respectively. For the analyses performed, it was found that manganese peroxidase (MnP) was the main contributor to delignification during the SSF step. MnP activity was up to 13.8 U/L for Ex-SSF pretreated black spruce, and 32.0 U/L for Ex-SSF pretreated corn stover, while the maximum MnP recorded in the negative controls was 1.4 ± 0.1 U/L. Ex-SSF pretreatment increased the cellulose crystallinity index (CrI) by 13% for black spruce and 4% for corn stover. But enzymatic digestibility of the Ex-SSF pretreated biomasses with 0.25 mL/g of enzyme led to 7.6 mg/L sugar recovery for black spruce, which is 2.3 times the raw biomass yield. The Ex-SSF pretreated corn stover led to 17.0 mg/L sugar recovery, which is a 44% improvement in sugar concentration compared to raw corn stover. However, increasing the enzyme content from 0.25 mL/g to 0.50 mg/L and 0.75 mg/L generated lower hydrolysis efficiency (the sugar recovery decreased). Full article

The demand for sustainable, low-cost bioprocesses has encouraged the development of alternative enzyme production strategies. This study investigated the purification and characterization of a crude enzymatic extract (CEE) rich in α-amylase from Coprinus comatus, using wheat milling by-products as substrate. The CEE was obtained by submerged culture, followed by biomass removal, centrifugation, and ultrafiltration to yield a partially purified enzyme (PE). CEE and PE were evaluated for chemical composition, antioxidant and antibacterial activity, toxicity (Artemia salina assay), and enzymatic performance. Toxicity assays confirmed that CEE was non-toxic. Antioxidant activity reached 213.34 µmol TE·gDE⁻¹ (DPPH assay), with a total phenolic content of 8.01 mg GAE·gDE⁻¹. No antibacterial activity was detected. CEE hydrolyzed 96.31% of starch in 180 min, releasing 10.85 g·L⁻¹ glucose, while PE achieved 98% hydrolysis and released 14.5 g·L⁻¹. Optimal α-amylase activity occurred at 50 °C and pH 5.5 (CEE) or 5.0 (PE). Calcium ions improved the enzymatic activity and thermal stability. CEE retained over 60% activity after 721 days under refrigeration (4 °C) or freezing (0 °C). Although lyophilization enhanced enzyme concentration, it increased production costs. SDS-PAGE revealed bands of ~67 kDa (α-amylase) and ~35 kDa (glucoamylase). These findings support the use of CEE as a sustainable, low-cost biocatalyst for industrial use. Full article

Lignocellulosic biomass, derived from plant materials, represents a renewable alternative to fossil fuels and plays a crucial role in advancing environmental sustainability. This systematic review investigates recent developments in the conversion of lignocellulosic biomass into biofuels, with a focus on pre-treatment technologies that enhance enzymatic hydrolysis, a critical step in efficient biofuel production. This review addresses two primary questions: (1) What are the most effective pre-treatment methods for enhancing enzymatic hydrolysis in lignocellulosic biomass conversion? (2) How do these pre-treatment methods compare in terms of efficiency, environmental impact, and economic feasibility? Consequently, studies were selected based on inclusion criteria that focus on research investigating these pre-treatment methods and their comparative performance. A structured search of original studies was applied across databases such as Crossref, Google Scholar, Scopus, PubMed, and Semantic Scholar, resulting in the inclusion of 17 peer-reviewed articles published between 2019 and 2024. The findings highlight effective pre-treatment methods that significantly improve enzymatic accessibility and bioethanol yields. However, ongoing challenges such as feedstock variability, process efficiency, and cost-effectiveness remain. These results highlight the need for further research and development to optimize conversion technologies and identify new areas for exploration. Full article

Spent hops from the supercritical extraction process represent a valuable source of xanthohumol (XN), a prenylated flavonoid with demonstrated anticancer, antidiabetic, antibacterial, and anti-inflammatory properties. However, XN is thermally sensitive and readily isomerizes into the less bioactive iso-XN at elevated temperatures, necessitating mild extraction conditions. Previous studies have shown that the pretreatment of plant biomass can enhance the extraction efficiency of bioactive compounds. In this study, various pretreatment methods—including physical (freeze–thaw, ultrasound, and microwave), chemical (acid and base hydrolysis), and enzymatic approaches—were applied to spent hops prior to extraction, and XN yields were compared to those obtained from untreated samples. The experiments, performed in triplicate, yielded meaningful results which helped understand the raw material’s behavior in applied conditions. Due to the compound’s high thermal sensitivity, ultrasound and microwave pretreatments require precise control to prevent excessive temperature increases, making low-temperature methods more suitable. Additionally, exposure to elevated pH adversely affected XN extraction efficiency, limiting the applicability of strong alkaline pretreatments. Among the evaluated methods, freeze–thaw pretreatment proved to be a simple and effective strategy, enhancing XN extraction yields by up to 10.7 ± 0.7% through the optimization of soaking time, the solid-to-liquid ratio, and the thawing temperature. Identifying an inexpensive and efficient pretreatment method could reduce extraction time while improving yield, contributing to the sustainable utilization of spent hops as an XN source. Full article

This study evaluates the feasibility of using banana peels as a substrate for cultivating fodder yeast biomass. Banana peels (BPs), representing approximately 38% of the total fruit weight, are rich in cellulose and hemicellulose, thus presenting a significant opportunity for valorisation. The study investigates the effects of microwave and ultrasound treatments on the hydrolysis efficiency of banana peels and the subsequent cultivation of yeast. Two yeast strains, Scheffersomyces stipitis and Meyerozyma guilliermondii, were cultivated in hydrolysates prepared using various methods, including acid–thermal, enzymatic, microwave, and ultrasound treatments. The results demonstrate that enzymatic hydrolysis following microwave or ultrasound pretreatment significantly enhances sugar release, supporting higher biomass yields. The maximum biomass concentration achieved was 7.68 g DM/L, with crude protein content reaching up to 45.46% DM. These results indicate that banana peels can be effectively utilised for single-cell protein production, providing a sustainable alternative for animal feed. The study underscores the potential of integrating microwave and ultrasound technologies in bioprocessing to enhance the efficiency and environmental sustainability of yeast cultivation. Full article

Sustainable valorization of lignocellulosic biomass, such as wheat straw (WS), into valuable products is key for efficient resource utilization. This study investigated an integrated strategy combining Irpex lacteus fermentation with subsequent alkali extraction to improve WS valorization. Alkali extraction parameters, including sodium hydroxide concentration, solid-to-liquid (S:L) ratio, temperature, and time, were optimized based on polysaccharide yield and purity. Optimal conditions were identified as 0.8 mol/L sodium hydroxide, a 1:25 S:L ratio, 90 °C, and 1 h, yielding 6.63% polysaccharides with 52.01% purity. Compared to untreated straw, the combined fermentation and alkali extraction treatment significantly altered the WS residue’s composition and structure, substantially reducing hemicellulose and acid detergent lignin while consequently increasing relative cellulose content. This enhanced cellulose accessibility resulted in a markedly improved glucose yield upon enzymatic hydrolysis, reaching 586 g/kg dry matter for the residue after combined treatment. Demonstrating a strong synergistic effect, this yield represents a 5.42-fold increase compared to untreated WS and a 3.30-fold increase compared to solely fermented straw. Analyses of SEM, FTIR, and XRD confirmed that the integrated treatment effectively disrupted the lignocellulosic structure by removing lignin and hemicellulose. This created a more porous morphology and increased cellulose exposure, which was deemed more critical for hydrolysis than the observed 18.58% increase in the cellulose crystallinity index relative to untreated straw. Thermogravimetric analysis further reflected these structural and compositional changes through altered thermal decomposition profiles. Therefore, integrating polysaccharide extraction with fungal fermentation is a highly effective strategy for improving resource efficiency in WS valorization. This approach enables the efficient co-production of valuable polysaccharides alongside significantly boosted platform sugar yields, offering a promising route towards more economically viable and sustainable WS utilization. Full article

Massive blooms of Ulva species, commonly known as green tides, pose serious ecological threats by disrupting coastal ecosystems and requiring costly removal efforts. This study presents a nature-based solution by seasonally valorizing Ulva ohnoi, a bloom-forming macroalga dominant in Jeju Island, South Korea. Biomass was collected across all four seasons and subjected to phylogenetic identification, biochemical characterization, and bioresource processing. Despite environmental fluctuations, tufA-based analysis confirmed U. ohnoi as the sole species present year-round. Carbohydrate content peaked in spring (55.35%) and was lowest in summer (45.74%), corresponding to maximum reducing sugar of 36.49 g/L in winter and 36.24 g/L in spring following acid-enzymatic hydrolysis. The maximum ethanol fermentation using Saccharomyces cerevisiae produced up to 17.12 g/L ethanol in spring with a yield of 0.47 g/g. Post-fermentation residues were enzymatically hydrolyzed into Ulva Ethanol Residue Medium (UERM), which supported yeast growth and fermentation comparable to commercial YPD medium, achieving final optical densities of 8.3–8.5 and ethanol production of 16.5–16.8 g/L. Alanine, valine, and proline were the most abundant amino acids in UERM, supporting its suitability as a nitrogen source. These findings highlight the potential of integrating green tide mitigation with renewable energy and nutrient recycling through seasonal, localized biorefineries aligned with circular marine bioeconomy principles. Full article

Although the broad-spectrum pesticide chlorpyrifos (CP) was banned in many developed countries, it is still widely used in developing countries. Its residues persist in the environment for unpredictable times. CP is toxic to various non-target organisms and humans and inhibits soil enzyme activity and bacterial and fungal abundance. This paper aimed to evaluate the effect of vermiremediation on soil chlorpyrifos content and soil fertility. The application of Eisenia fetida or vermicompost was studied in terms of soil chlorpyrifos concentration, microbial biomass content, and enzymatic activities in a 120-day trial. Pesticide application rates were 0, 25, and 50 ppm. The CP did not affect the earthworm survival rate at the tested doses. The earthworms markedly increased microbial biomass carbon and the activity of β-glucosamminidase, while the vermicompost had a noticeably positive effect mainly on alkaline phosphatase activity. Finally, although the vermiremediation techniques studied did not perform a bioremediation activity, they proved effective in improving the biological fertility of the soil in the presence of high concentrations of chlorpyrifos. Full article

Physical pretreatments play a crucial role in reducing the recalcitrance of lignocellulosic biomass, facilitating its conversion into fermentable sugars for bioenergy and chemical applications. This study critically reviews physical pretreatment approaches, including mechanical comminution, irradiation (ultrasound, microwave, gamma rays, and electron beam), extrusion, and pulsed electric field. The discussion covers the mechanisms of action, operational parameters, energy efficiency, scalability challenges, and associated costs. Methods such as ultrasound and microwave induce structural changes that enhance enzymatic accessibility, while extrusion combines thermal and mechanical forces to optimize hydrolysis. Mechanical comminution is most effective during short periods and when combined with other techniques to overcome limitations such as high energy consumption. Innovative approaches, such as pulsed electric fields, show significant potential but face challenges in large-scale implementation. This study provides technical and strategic insights into developing more effective physical pretreatments aligned with economic feasibility and industrial sustainability. Full article