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This study explores the potential of producing bioethanol from seaweed biomass and reusing the residues as antioxidant compounds. Various types of seaweed, including red (Gelidium amansii, Gloiopeltis furcata, Pyropia tenera), brown (Saccharina japonica, Undaria pinnatifida, Ascophyllum nodosum), and green species (Ulva intestinalis, Ulva prolifera, Codium fragile), were pretreated with dilute acid and enzymes and subsequently processed to produce bioethanol with Saccharomyces cerevisiae BY4741. Ethanol production followed the utilization of sugars, resulting in the highest yields from red algae > brown algae > green algae due to their high carbohydrate content. The residual biomass was extracted with water, ethanol, or methanol to evaluate its antioxidant activity. Among the nine seaweeds, the A. nodosum bioethanol residue extract (BRE) showed the highest antioxidant activity regarding the 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity, ferric reducing antioxidant power (FRAP), and reactive oxygen species (ROS) inhibition of H2O2-treated RAW 264.7 cells. These by-products can be valorized, contributing to a more sustainable and economically viable biorefinery process. This dual approach not only enhances the utilization of marine resources but also supports the development of high-value bioproducts.

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Hydrogen-ethanol co-production can significantly improve the energy conversion efficiency of corn stalk (CS). In this study, with CS as the raw material, the co-production characteristics of one-step and two-step photo-fermentation hydrogen production (PFHP) and ethanol production were investigated. In addition, the gas and liquid characteristics of the experiment were analyzed. The kinetics of hydrogen-ethanol co-production was calculated, and the economics of hydrogen and ethanol were analyzed. Results of the experiments indicated that the two-step hydrogen-ethanol co-production had the best hydrogen production performance when the concentration of CS was 25 g/L. The total hydrogen production was 350.08 mL, and the hydrogen yield was 70.02 mL/g, which was 2.45 times higher than that of the one-step method. The efficiency of hydrogen-ethanol co-production was 17.79 %, which was 2.76 times more efficient than hydrogen compared to fermentation with hydrogen. The result provides technical reference for the high-quality utilization of CS.

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Many anaerobic microorganisms use the bifunctional aldehyde and alcohol dehydrogenase enzyme, AdhE, to produce ethanol. One such organism is Clostridium thermocellum, which is of interest for cellulosic biofuel production. In the course of engineering this organism for improved ethanol tolerance and production, we observed that AdhE was a frequent target of mutations. Here, we characterized those mutations to understand their effects on enzymatic activity, as well ethanol tolerance and product formation in the organism. We found that there is a strong correlation between NADH-linked alcohol dehydrogenase (ADH) activity and ethanol tolerance. Mutations that decrease NADH-linked ADH activity increase ethanol tolerance; correspondingly, mutations that increase NADH-linked ADH activity decrease ethanol tolerance. We also found that the magnitude of ADH activity did not play a significant role in determining ethanol titer. Increasing ADH activity had no effect on ethanol titer. Reducing ADH activity had indeterminate effects on ethanol titer, sometimes increasing and sometimes decreasing it. Finally, this study shows that the cofactor specificity of ADH activity was found to be the primary factor affecting ethanol yield. We expect that these results will inform efforts to use AdhE enzymes in metabolic engineering approaches.

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Acetic acid is a common inhibitor present in lignocellulose hydrolysate, which inhibits the ethanol production by yeast strains. Therefore, the cellulosic ethanol industry requires yeast strains that can tolerate acetic acid stress. Here we demonstrate that overexpressing a yeast native arginase-encoding gene, CAR1, renders Saccharomyces cerevisiae acetic acid tolerance. Specifically, ethanol yield increased by 27.3% in the CAR1-overexpressing strain compared to the control strain under 5.0 g/L acetic acid stress. The global intracellular amino acid level and compositions were further analyzed, and we found that CAR1 overexpression reduced the total amino acid content in response to acetic acid stress. Moreover, the CAR1 overexpressing strain showed increased ATP level and improved cell membrane integrity. Notably, we demonstrated that the effect of CAR1 overexpression was independent of the spermidine and proline metabolism, which indicates novel mechanisms for enhancing yeast stress tolerance. Our studies also suggest that CAR1 is a novel genetic element to be used in synthetic biology of yeast for efficient production of fuel ethanol.

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Aim: Endogenous ethanol production emerges as a mechanism of nonalcoholic steatohepatitis, obesity, diabetes and auto-brewery syndrome. Methods: To identify ethanol-producing microbes in humans, we used the NCBI taxonomy browser and the PubMed database with an automatic query and manual verification. Results: 85 ethanol-producing microbes in human were identified. Saccharomyces cerevisiae, Candida and Pichia were the most represented fungi. Enterobacteriaceae was the most represented bacterial family with mainly Escherichia coli and Klebsiella pneumoniae. Species of the Lachnospiraceae and Clostridiaceae family, of the Lactobacillales order and of the Bifidobacterium genus were also identified. Conclusion: This catalog will help the study of ethanol-producing microbes in human in the pathophysiology, diagnosis, prevention and management of human diseases associated with endogenous ethanol production.

Our bodies are home to a community of tiny living organisms like bacteria, viruses and archaea, collectively known as the microbiota. These microbes are crucial for our well-being and the proper functioning of our bodies. Certain things, like antibiotics or an imbalanced diet, can disturb this microbial community, known as dysbiosis. This can lead to illness. This review focuses on dysbiosis related to the production of ethanol, a type of alcohol, within our bodies. While the disruption of the microbiota has been linked to several health issues, the role of ethanol production in this is not well explored. This review aims to shed light on the microbes involved in this process. We found 85 microbes capable of producing ethanol in the human body, including 61 bacterial and 24 yeast species. This review provides a detailed updated catalog of ethanol-producing microbes in humans. Understanding these microbes and their role in diseases related to ethanol production could pave the way for better diagnostic tools and treatments in the future.

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Cu-based catalysts have been shown to selectively catalyze CO2 photoreduction to C2+ solar fuels. However, they still suffer from poor activity and low selectivity. Herein, we report a high-performance carbon nitride supported Cu single-atom catalyst featuring defected low-coordination Cu-N2 motif (Cu-N2-V). Lead many recently reported photocatalysts and its Cu-N3 and Cu-N4 counterparts, Cu-N2-V exhibits superior photocatalytic activity for CO2 reduction to ethanol and delivers 69.8 µmol g-1 h-1 ethanol production rate, 97.8 % electron-based ethanol selectivity, and a yield of ~10 times higher than Cu-N3 and Cu-N4. Revealed by the extensive experimental investigation combined with DFT calculations, the superior photoactivity of Cu-N2-V stems from its defected Cu-N2 configuration, in which the Cu sites are electron enriched and enhance electron delocalization. Importantly, Cu in Cu-N2-V exist in both Cu+ and Cu2+ valence states, although predominantly as Cu+. The Cu+ sites support the CO2 activation, while the co-existence of Cu+/Cu2+ sites are highly conducive for strong *CO adsorption and subsequent *CO-*CO dimerization enabling C-C coupling. Furthermore, the hollow microstructure of the catalyst also promotes light adsorption and charge separation efficiency. Collectively, these make Cu-N2-V an effective and high-performance catalyst for the solar-driven CO2 conversion to ethanol. This study also elucidates the C-C coupling reaction path via *CO-*CO to *COCOH and rate-determining step, and reveals the valence state change of partial Cu species from Cu+ to Cu2+ in Cu-N2-V during CO2 photoreduction reaction.

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Poplar is widely used in the paper industry and accompanied by abundant branches waste, which is potential feedstock for bioethanol production. Acid-chlorite pretreatment can selectively remove lignin, thereby significantly increasing enzymatic efficiency. Moreover, lignin residues valorization via gasification-syngas fermentation can achieve higher fuel yield. Herein, environmental and economic aspects were conducted to assess technological routes, which guides further process optimization. Life cycle assessment results show that wood-based biorefineries especially coupling scenarios have significant advantages in reducing global warming potential in contrast to fossil-based automotive fuels. Normalization results indicate that acidification potential surpasses other indicators as the primary impact category. In terms of economic feasibility, coupling scenarios present better investment prospects. Bioethanol yield is the most critical factor affecting market competitiveness. Minimum ethanol selling price below ethanol international market price is promising with higher-levels technology. Further work should be focused on technological breakthrough, consumable reduction or replacement.

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Here, Baijiu distillers' grains (BDGs) were employed in biorefinery development to generate value-added co-products and bioethanol. Through ethyl acetate extraction at a 1:6 solid-liquid ratio for 10 h, significant results were achieved, including 100 % lactic acid and 92 % phenolics recovery. The remaining BDGs also achieved 99 % glucan recovery and 81 % glucan-to-glucose conversion. Simultaneous saccharification and fermentation of remaining BDGs at 30 % loading resulted in 78.5 g bioethanol/L with a yield of 94 %. The minimum selling price of bioethanol varies from $0.149-$0.836/kg, contingent on the co-product market prices. The biorefinery processing of one ton of BDGs caused a 60 % reduction in greenhouse gas emissions compared to that of the traditional production of 88 kg corn-lactic acid, 70 kg antioxidant phenolics, 234 kg soybean protein, and 225 kg corn-bioethanol, along with emissions from BDG landfilling. The biorefinery demonstrated a synergistic model of cost-effective bioethanol production and low-carbon emission BDGs treatment.

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Ethanol is the psychoactive substance identified most frequently in post-mortem specimens. Unfortunately, interpreting post-mortem ethanol concentrations can be difficult because of post-mortem alcohol redistribution and the possibility of post-mortem alcohol neogenesis. Indeed, in the time interval between death and sample collection, the decedent may be exposed to non-controlled environments for an extended period, promoting microbial colonization. Many authors report that in the presence of carbohydrates and other biomolecules, various species of bacteria, yeast, and fungi can synthesize ethanol and other volatile substances in vitro and in vivo. The aim of this study was to study the impact of several variables on microbial ethanol production as well as develop a mathematical model that could estimate the microbial-produced ethanol in correlation with the most significant consensual produced higher alcohol, 1-propanol. An experimental setup was developed using human blood samples and cadaveric fragments incubated under strictly anaerobic conditions to produce a novel substrate, "cadaveric putrefactive blood" mimicking post-mortem corpse conditions. The samples were analyzed daily for ethanol and 1-propanol using an HS-GC-FID validated method. The formation of ethanol was evaluated considering different parameters such as putrefactive stage, blood glucose concentration, storage temperature, and storage time. Statistical analysis was performed using the Mann-Whitney non-parametric test and simple linear regression. The results indicate that the early putrefactive stage, high blood glucose concentration, high temperature, and time of incubation increase microbial ethanol production. In addition, the developed mathematical equation confirms the feasibility of using 1-propanol as a marker of post-mortem ethanol production.

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Bamboo is considered a renewable energy bioresource for solving the energy crisis and climate change. Dendrocalamus branddisii (DB) was first subjected to sulfomethylation reaction at 95°C for 3 h, followed by Fenton oxidation pretreatment at 22°C for 24 h. The synergistic effect of combined pretreatment dramatically improved enzymatic digestibility efficiency, with maximum yield of glucose and ethanol content of 71.11% and 16.47 g/L, respectively, increased by 4.7 and 6.11 time comparing with the single Fenton oxidation pretreatment. It was found that the hydrophobicity of substrate, content of surface lignin, degree of polymerization, and specific surface area have significant effects on the increase of enzymatic saccharification efficiency. It also revealed that sulfomethylation pre-extraction can improve the hydrophilicity of lignin, leading to the lignin dissolution, which was beneficial for subsequent Fenton pretreatment of bamboo biomass. This work provides some reference for Fenton oxidation pretreatment of bamboo biomass, which can not only promote the utilization of bamboo in southwest China, but also enhances the Fenton reaction in the bamboo biorefinery.

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Traditional industrial Saccharomyces cerevisiae could not metabolize xylose due to the lack of a specific enzyme system for the reaction from xylose to xylulose. This study aims to metabolically remould industrial S. cerevisiae for the purpose of utilizing both glucose and xylose with high efficiency. Heterologous gene xylA from Piromyces and homologous genes related to xylose utilization were selected to construct expression cassettes and integrated into genome. The engineered strain was domesticated with industrial material under optimizing conditions subsequently to further improve xylose utilization rates. The resulting S. cerevisiae strain ABX0928-0630 exhibits a rapid growth rate and possesses near 100% xylose utilization efficiency to produce ethanol with industrial material. Pilot-scale fermentation indicated the predominant feature of ABX0928-0630 for industrial application, with ethanol yield of 0.48 g/g sugars after 48 hours and volumetric xylose consumption rate of 0.87 g/l/h during the first 24 hours. Transcriptome analysis during the modification and domestication process revealed a significant increase in the expression level of pathways associated with sugar metabolism and sugar sensing. Meanwhile, genes related to glycerol lipid metabolism exhibited a pattern of initial increase followed by a subsequent decrease, providing a valuable reference for the construction of efficient xylose-fermenting strains.

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Since the implementation of the waste separation policy, the disposal of source-separated food waste (FW) has been more strictly required. Traditional source-separated FW treatment technologies, such as anaerobic digestion (AD) and aerobic composting (AC), suffer from low resource utilization efficiency and poor economic benefits. It is one of the main limiting factors for the promotion of waste separation. Life cycle assessment (LCA) was conducted for five municipal solid waste (MSW) treatment technologies, compared their environmental impacts, and analyzed the impact of waste separation ratios to determine whether biorefinery is a promising way to support waste source separation. The results showed that black soldier fly (BSF) treatment had the lowest net global warming potential (GWP) of all technologies, reduced by 40.8 % relative to the non-source-separated treatment. Ethanol production had the second-lowest net environmental impact potential because bioethanol replaces fossil fuel to avoid the emission of pollutants from its combustion. When two biorefinery technologies with excellent efficiency to avoid environmental impact are used to treat source-separated FW, the increase in the percentage of waste separation will help reduce the environmental impact of MSW treatment. The application of biorefinery technologies is considered a viable option for source-separated FW treatment. AC should not be widely promoted because it showed the worst net environmental benefits, and waste separation will elevate the environmental impact of its treatment process.

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Increased human population and the rapid decline of fossil fuels resulted in a global tendency to look for alternative fuel sources. Environmental concerns about fossil fuel combustion led to a sharp move towards renewable and environmentally friendly biofuels. Ethanol has been the primary fossil fuel alternative due to its low carbon emission rates, high octane content and comparatively facile microbial production processes. In parallel to the increased use of bioethanol in various fields such as transportation, heating and power generation, improvements in ethanol production processes turned out to be a global hot topic. Ethanol is by far the leading yeast output amongst a broad spectrum of bio-based industries. Thus, as a well-known platform microorganism and native ethanol producer, baker's yeast Saccharomyces cerevisiae has been the primary subject of interest for both academic and industrial perspectives in terms of enhanced ethanol production processes. Metabolic engineering strategies have been primarily adopted for direct manipulation of genes of interest responsible in mainstreams of ethanol metabolism. To overcome limitations of rational metabolic engineering, an alternative bottom-up strategy called inverse metabolic engineering has been widely used. In this context, evolutionary engineering, also known as adaptive laboratory evolution (ALE), which is based on random mutagenesis and systematic selection, is a powerful strategy to improve bioethanol production of S. cerevisiae. In this review, we focus on key examples of metabolic and evolutionary engineering for improved first- and second-generation S. cerevisiae bioethanol production processes. We delve into the current state of the field and show that metabolic and evolutionary engineering strategies are intertwined and many metabolically engineered strains for bioethanol production can be further improved by powerful evolutionary engineering strategies. We also discuss potential future directions that involve recent advancements in directed genome evolution, including CRISPR-Cas9 technology.

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Potato peel waste (PPW), a zero-value by-product generated from potato processing, is a promising fermentation substrate due to its large quantity of starch, nonstarch polysaccharides, lignin, protein, and lipid. Rhizopus oryzae is a filamentous fungus that is mainly known as a lactic acid producer and can ferment various agro-wastes. This study aimed to use R. oryzae for the fermentation of PPW. A series of batch fermentations were conducted to investigate the effects of different PPW loading rates (2%-8%) and particle sizes (0-4 mm). Under an initial PPW loading rate of 8% and particle size of 1-2 mm, the maximum ethanol (18.83 g/L) and lactic acid (3.14 g/L) concentrations, the highest ethanol (9.41 g/L·day) and lactic acid (1.89 g/L·day) average production rates were obtained. Under these conditions, the yield of ethanol and lactic acid was 0.235 g/gPPW and 0.039 g/gPPW, respectively. R. oryzae was shown to utilize PPW as a substrate to produce value-added bioproducts such as ethanol (major product) and lactic acid.

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Photoconversion of CO2 and H2 O into ethanol is an ideal strategy to achieve carbon neutrality. However, the production of ethanol with high activity and selectivity is challenging owing to the less efficient reduction half-reaction involving multi-step proton-coupled electron transfer (PCET), a slow C-C coupling process, and sluggish water oxidation half-reaction. Herein, a two-dimensional/two-dimensional (2D/2D) S-scheme heterojunction consisting of black phosphorus and Bi2 WO6 (BP/BWO) was constructed for photocatalytic CO2 reduction coupling with benzylamine (BA) oxidation. The as-prepared BP/BWO catalyst exhibits a superior photocatalytic performance toward CO2 reduction, with a yield of 61.3 µmol g-1 h-1 for ethanol (selectivity of 91 %).In situ spectroscopic studies and theoretical calculations reveal that S-scheme heterojunction can effectively promote photogenerated carrier separation via the Bi-O-P bridge to accelerate the PCET process. Meanwhile, electron-rich BP acts as the active site and plays a vital role in the process of C-C coupling. In addition, the substitution of BA oxidation for H2 O oxidation can further enhance the photocatalytic performance of CO2 reduction to C2 H5 OH. This work opens a new horizon for exploring novel heterogeneous photocatalysts in CO2 photoconversion to C2 H5 OH based on cooperative photoredox systems.

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BACKGROUND: The thermotolerant yeast is beneficial in terms of efficiency improvement of processes and reduction of costs, while Saccharomyces cerevisiae does not efficiently grow and ferment at high-temperature conditions. The sterol composition alteration from ergosterol to fecosterol in the cell membrane of S. cerevisiae affects the thermotolerant capability. RESULTS: In this study, S. cerevisiae ERG5, ERG4, and ERG3 were knocked out using the CRISPR-Cas9 approach to impact the gene expression involved in ergosterol synthesis. The highest thermotolerant strain was S. cerevisiae ERG5ΔERG4ΔERG3Δ, which produced 22.1 g/L ethanol at 37 °C using the initial glucose concentration of 50 g/L with an increase by 9.4% compared with the wild type (20.2 g/L). The ethanol concentration of 9.4 g/L was produced at 42 ℃, which was 2.85-fold of the wild-type strain (3.3 g/L). The molecular mechanism of engineered S. cerevisiae at the RNA level was analyzed using the transcriptomics method. The simultaneous deletion of S. cerevisiae ERG5, ERG4, and ERG3 caused 278 up-regulated genes and 1892 down-regulated genes in comparison with the wild-type strain. KEGG pathway analysis indicated that the up-regulated genes relevant to ergosterol metabolism were ERG1, ERG11, and ERG5, while the down-regulated genes were ERG9 and ERG26. S. cerevisiae ERG5ΔERG4ΔERG3Δ produced 41.6 g/L of ethanol at 37 °C with 107.7 g/L of corn liquefied glucose as carbon source. CONCLUSION: Simultaneous deletion of ERG5, ERG4, and ERG3 resulted in the thermotolerance improvement of S. cerevisiae ERG5ΔERG4ΔERG3Δ with cell viability improvement by 1.19-fold at 42 °C via modification of steroid metabolic pathway. S. cerevisiae ERG5ΔERG4ΔERG3Δ could effectively produce ethanol at 37 °C using corn liquefied glucose as carbon source. Therefore, S. cerevisiae ERG5ΔERG4ΔERG3Δ had potential in ethanol production at a large scale under supra-optimal temperature.

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Enhancing the degradation of lignocellulosic structure is essential for the efficient use of corn stover. This study investigated the effects of using urea combined with steam explosion on the enzymatic hydrolysis and ethanol production of corn stover. The results demonstrated that 4.87% urea addition and 1.22 MPa steam pressure were optimal for ethanol production. The highest reducing sugar yield (350.12 mg/g) was increased by 116.42% (p < 0.05), and the corresponding degradation rates of cellulose, hemicellulose, and lignin in pretreated corn stover were increased by 40.26%, 45.89% and 53.71% compared with the untreated corn stover (p < 0.05). Moreover, the maximal sugar alcohol conversion rate was approximately 48.3%, and the ethanol yield reached 66.5%. In addition, the key functional groups in corn stover lignin under combined pretreatment were identified. These findings offer new insights into corn stover pretreatment and can help develop feasible technologies to enhance ethanol production.

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The bacteria Clostridium cellulolyticum is a promising candidate for consolidated bioprocessing (CBP). However, genetic engineering is necessary to improve this organism's cellulose degradation and bioconversion efficiencies to meet standard industrial requirements. In this study, CRISPR-Cas9n was used to integrate an efficient ß-glucosidase into the genome of C. cellulolyticum, disrupting lactate dehydrogenase (ldh) expression and reducing lactate production. The engineered strain showed a 7.4-fold increase in ß-glucosidase activity, a 70% decrease in ldh expression, a 12% increase in cellulose degradation, and a 32% increase in ethanol production compared to wild type. Additionally, ldh was identified as a potential site for heterologous expression. These results demonstrate that simultaneous ß-glucosidase integration and lactate dehydrogenase disruption is an effective strategy for increasing cellulose to ethanol bioconversion rates in C. cellulolyticum.

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A high sugar concentration is used as a starting condition in alcoholic fermentation by budding yeast, which shows changes in intracellular state and cell morphology under conditions of high-sugar stress. In this study, we developed artificial intelligence (AI) models to predict ethanol yields in yeast fermentation cultures under conditions of high-sugar stress using cell morphological data. Our method involves the extraction of high-dimensional morphological data from phase contrast images using image processing software, and predicting ethanol yields by supervised machine learning. The neural network algorithm produced the best performance, with a coefficient of determination (R2) of 0.95, and could predict ethanol yields well even 60 min in the future. Morphological data from cells cultured in low-glucose medium could not be used for accurate prediction under conditions of high-glucose stress. Cells cultured in high-concentration glucose medium were similar in terms of morphology to cells cultured under high osmotic pressure. Feeding experiments revealed that morphological changes differed depending on the fermentation phase. By monitoring the morphology of yeast under stress, it was possible to understand the intracellular physiological conditions, suggesting that analysis of cell morphology can aid the management and stable production of desired biocommodities.

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The present study evaluated efficiency of wheat straw (WS) hydrolysate obtained through fungal pre-treatment to produce ethanol and electricity in an electrochemical bioreactor. Three white rot fungi Phanerochaete chrysosporium, Phlebia floridensis and Phlebia brevispora were used to degrade WS for hydrolysate preparation, Lignocellulolytic enzyme production was also monitored during the pretreatment. Yeast Pichia fermentans was allowed to ferment all three hydrolysates up to 12 days. The yeast showed maximum electrochemical response as open circuit voltage (0.672 V), current density 542.42 mA m-2, and power density of 65.09 mW m-2 on 12th day in the hydrolysate prepared using Phlebia floridensis. Maximum ethanol production of 9.2% (w/v) was achieved on 7th day with a fermentation efficiency of about 62.1%. Further, the coulombic efficiency improved from 0.06 to 1.46% during 12 days of the experiment. Thus, the results indicated towards the possible conversion of lignocellulosic biomass into bioethanol along with bioelectricity generation.