Biorefinery Feedstock Research Articles

Maximizing yields of furfural and 5‐hydroxymethylfurfural in side streams from steam explosion of lignocellulosic residues

AbstractThe demand for renewable energy and chemicals from biomass resources has led to the development of methods for biorefining lignocellulosic materials into pellets and value‐added chemicals. This has, in turn, driven a search for alternative raw materials to use as feedstock in such biorefineries. This study proposes the inclusion of low‐grade lignocellulosic residues from agriculture and forestry, such as straw and woody biomass with a high bark content, in the feedstock mix for steam explosion (STEX) based biorefineries. It focuses on exploring how the use of low‐grade residues affects the yield of value‐added chemicals that arise as side streams during the steam explosion of lignocellulosic biomass and if acetic acid impregnation of the biomass prior to STEX pretreatment will further improve yields of valuable side stream chemicals. The raw materials were impregnated with water/acetic acid before being subjected to STEX pretreatment, using high temperatures (190 °C–223 °C), and a reaction time of 8 min before pressure release. Value‐added chemicals were identified in two separate aqueous side streams. In the condensed process effluents, the most abundant compounds were acetic acid (1.2 g*kg−1 dry input biomass) and furfural (1.4 g*kg−1 dry input biomass), and the highest yields were found in the samples from mixed spruce and branches and tops (BRAT) at high temperatures. Filtrate samples produced from washing the steam‐exploded biomass contained acetic acid (53.6 g*kg−1 dry input biomass), furfural (4.1–7.9 g*kg−1 dry input biomass) and 5‐hydroxymethylfurfural (5‐HMF) (9.0 g*kg−1 dry input biomass) as the most abundant compounds and highest yields of target compounds were found in samples of spruce alone and of spruce mixed with BRAT. All compounds in the side streams were identified and quantified using quantitative 1H nuclear magnetic resonance spectroscopy (qNMR). This study demonstrates that high yields of valuable chemicals are present in the aqueous side streams of pellet production using alternative feedstocks such as forestry and agricultural residues.

Characterization of Spent Grain from Irish Whiskey Distilleries for Biorefinery Feedstock Potential to Produce High-Value Chemicals and Biopolymers

Distiller’s spent grain (DSG) is a byproduct generated in large quantities during the mashing process, particularly in the production of alcoholic beverages such as whiskey. This study aimed to characterize DSG from nine different distilleries as a potential biorefinery feedstock for the synthesis of high-value bioproducts. Key components, including protein (12.38–26.32%), cellulose (11.75–32.75%), hemicellulose (6.97–19.47%), lignin (8.44–15.71%), and total phenolics (1.42 to 3.97 mg GAE/g), were analyzed to evaluate their variability and suitability for industrial applications. The results reveal that DSG composition varies significantly across distilleries due to differences in processing techniques, even though the starting grain composition had minimal influence. Statistical analysis highlighted the variability of water- and ethanol-soluble extractives (17.34–31.77%) and their potential impact on product consistency. This compositional variability highlights the importance of understanding DSG’s structural properties to optimize its use as a lignocellulosic biomass feedstock. This study emphasizes the potential for utilizing DSG in the production of nanocellulose, bioplastics, phenolic resins, and other sustainable materials, thereby contributing to the circular economy. By linking compositional insights to specific applications, this work establishes a foundation for tailored utilization of DSG in biopolymer production and chemical synthesis. These findings provide valuable insights for biorefinery operations, addressing both sustainability challenges and the economic potential of industrial byproducts.

Innovative Strategies for Microalgae-Based Bioproduct Extraction in Biorefineries: Current Trends and Future Solutions Integrating Wastewater Treatment

Recently, microalgae have emerged as a promising feedstock for biorefineries, offering significant potential for producing high-value bio-based products in areas such as biofuels, nutraceuticals, and environmental management. This study, therefore, undertook an in-depth bibliometric review of 535 articles out of 736 publications published between 2010 and 2024 and sourced from the Scopus database. With the use of the VOS-viewer software, this work identified the major trends within significant research areas in terms of focus and global collaboration networks that pertain to microalgae-based bioproducts. Also, it explored cutting-edge techniques for bioproduct extraction and processing that are both efficient and eco-friendly. This analysis also showed a remarkable growth in output, with peaks in the year 2022, reflecting an interest in renewable energy and methods of sustainable production. The main keywords identified deal with subject areas such as energy, environmental science, and chemical engineering. The dominant technologies referred to dealing with lipid extraction, bio-crude production, and nutrient recycling. While addressing cost, scale-up, and environmental concerns, there is still a need to improve extraction techniques like ultrasonic treatment, supercritical fluid treatment, and enzymatic treatment. Other emerging areas of research include genetic engineering and integrated biorefinery models, which are expected to provide a roadmap for future advancements in the field. The challenges innate in meeting this through innovation and optimization will be the key to realizing the full potential of microalgae to contribute to the circular bioeconomy.

Integrated biorefining of rapeseed straw for ethanol, biogas, and mycoprotein production

Rapeseed straw, a widely available waste stream typically disposed of by field burning, was utilized as a biorefinery feedstock for biofuel and mycoprotein production across three different scenarios. Scenario 1 focused on biomethane production and optimization, while scenarios 2 and 3 aimed at ethanol and mycoprotein production using, an edible ascomycete fungus, Neurospora intermedia in anaerobic and aerobic cultivation, respectively. Hydrolysis residues also underwent anaerobic digestion to boost up the biorefinery. Without the addition of any chemicals, the straw structure was modified by hydrothermal pretreatments at 120–180 °C for 1–3 h. The structural and morphological improvements were followed by scanning electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller methods. Specific surface area, total pore volume, and average pore width of the straw pretreated at 180 °C for 3 h were approximately 1.5, 3, and 2 times higher than that of the untreated straw, facilitating enzyme permeation. The highest ethanol yield (12.2 g/L) was achieved after pretreatment at 180 °C for 3 h. The highest methane yields were 308 and 365 N mL/g volatile solids for solid and liquid fractions, respectively, after pretreatment at 150 °C for 1 and 3 h. Hydrolysis residues from straw pretreated at 120 °C for 1 h yielded 290 N mL/g volatile solids via anaerobic digestion. In scenario 1, from each tonne of straw pretreated at 150 °C for 1 h, 241.8 m3 methane was produced (272.8 L gasoline-equivalent). In scenario 2, combined ethanol production and biogas from residues pretreated at 120 °C for 1 h enhanced energy yield to 275.2 L gasoline-equivalent. In scenario 3, 191.7 kg mycoprotein and 124.8 m3 methane were produced per tonne of straw pretreated at 150 °C for 1 h. It was concluded that biorefining of rapeseed straw holds significant promise for the simultaneous production of ethanol, biogas, and mycoprotein; however, the structure of untreated straw is highly recalcitrant, making a suitable pretreatment necessary before the bioconversions.

Review of recent advances in utilising aquaculture wastewater for algae cultivation and microalgae-based bioproduct recovery.

Aquaculture operations produce large amounts of wastewater contaminated with organic matter, nitrogenous compounds, and other emerging contaminants; when discharged into natural water bodies, it could result in ecological problems and severely threaten aquatic habitats and human health. However, using aquaculture wastewater in biorefinery systems is becoming increasingly crucial as advancements in valuable bioproduct production continue to improve economic feasibility. Research on utilisingmicroalgaeas an alternative to producing biomass and removing nutrients from aquaculture wastewater has been extensively studied over the past decades. Microalgae have the potential to use carbon dioxide (CO2) effectively and significantly reduce carbon footprint, and the harvested biomass can also be used as aquafeed. Furthermore, aquaculture wastewater enriched with phosphorus (P) is a potential resource for P recovery for the production of biofertiliser. This will reduce the P supply shortage and eliminate the environmental consequences of eutrophication. In this context, the present review aims to provide a comprehensive overview of the current state of the art in a generation, as well as the characteristics and environmental impact of aquaculture wastewater reported by the most recent research. Furthermore, the review synthesized recent developments in algal biomass cultivation using aquaculture wastewater and its utilisation as biorefinery feedstocks for producing value-added products, such as aquafeeds, bioethanol, biodiesel, biomethane, and bioenergy. This integrated process provides a sustainable method for recovering biomass and water, fully supporting the framework of a circular economy in aquaculture wastewater treatment via resource recovery.

Corn biomass as a feedstock for biorefinery: a bibliometric analysis of research on bioenergy, biofuel and value‐added products

AbstractLimited research has been dedicated to exploring the potential reuse and creation of value‐added products from corn stover. Existing gaps in current research underscore the need for waste biorefineries that adhere to the principles of a circular bioeconomy to maximize the value of corn stover. This review uses bibliometric analysis from the past decade to examine the potential and pathways for converting corn stover into energy and value‐added products within the biorefinery framework. The data were processed using the Web of Science® database and analyzed with the VosViewer® bibliometric software's, Bibliometrix package in R and Gephi, generating keyword‐based maps. A total of 2557 experimental articles and 30 reviews on corn stover research were analyzed. The bibliometric study revealed that the primary research focuses on pretreatment technologies for converting corn stover into value‐added products, bioenergy and biofuels. The main technologies employed include acid, alkaline and enzymatic hydrolysis, as well as torrefaction anaerobic digestion and steam explosion. The pretreatment processes yield sugars, xylooligosaccharides and organic acids. Additionally, the studies explored the use of corn stover biochar for soil remediation and adsorption processes. This review aims to enhance the understanding of technological pathways explored in previous research, contributing to the evaluation of sustainable processes for utilizing corn stover byproducts. Ultimately, it promotes environmentally conscious agroindustry practices that align with circular economy principles and sustainable development.

Bioenergy potential from Ecuadorian lignocellulosic biomass: Physicochemical characterization, thermal analysis and pyrolysis kinetics

Lignocellulosic biomass offers a sustainable and renewable method for producing high-quality fuels and value-added chemicals. In this study, residues from peach palm (top, inner sheath, and meristem), sugarcane (top), and pineapple (mother plant) were characterized based on their physicochemical properties and thermal degradation behavior to estimate their bioenergy potential. The biomass residue kinetic constraints were analyzed using three isoconversional models: the Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and differential Friedman (DF) models. Physicochemical characterization showed the peach palm top's notably high cellulose content of 35.71 ± 0.47 % wt. Calorific values of the residues ranged from 13.73 ± 0.08 to 16.91 ± 0.90 MJ kg−1. X-ray diffraction analysis indicated the carbonaceous and crystalline nature of the biomass residues. Mean activation energy values ranged from 105.02 to 370.10 kJ mol−1 for KAS, 111.50–360.99 kJ mol−1 for FWO, and 108.60–360.27 kJ mol−1 for DF. Finally, thermodynamic analysis revealed the endothermic nature of the pyrolysis process across the entire conversion range for the samples. Overall, these samples demonstrate major potential as feedstock for biorefineries and the development of Ecuador's circular economy.

Bioconversion of sugar beet molasses into functional exopolysaccharides by beet juice-derived lactic acid bacteria

Sugar beet molasses, a sugar-rich byproduct of sugar beet industry, have great potential as a biorefinery feedstock for the production of value-added bio-products by microbial fermentation. The production of functional exopolysaccharides (EPS) by lactic acid bacteria (LAB) represents a promising strategy for valorizing sugar processing waste. This study screened and identified high-efficiency EPS-producing LAB isolates from beet juice. Among the 32 isolates, six LAB strains including Limosilactobacillus fermentum YL7, Lactiplantibacillus plantarum YL4, TC10, and CJ10, Leuconostoc mesenteroides TCT3 and TCT4, exhibited efficient bio-conversion of beet molasses to LAB-EPS, with yields varying from 13.96 to 22.26 g/L. Antioxidant activity analysis revealed that EPS from these strains displayed significant scavenging activities against ABTS+, DPPH, and -OH radicals. Notably, EPS produced by L. plantarum TC10 and L. fermentum YL7 exhibited superior ABTS + scavenging capacity, with rates up to 99.48% and 95.89% at 4 mg/mL, respectively. Additionally, EPS from strains YL4, YL7, TCT3 and TCT4 showed significant antibiofilm activity against S. aureus and E. coli, with EPS-YL7 inhibiting S. aureus biofilm formation by up to 90.49% at 8.0 mg/mL. Furthermore, EPS from strains TCT4 demonstrated great tolerance to digestive fluid compared to EPS from other strains, with a retention rate of 72% at the end of intestinal digestion. These findings suggest that EPS-producing LAB strains from beet juice can efficiently convert beet molasses into valuable EPS utilized as functional food ingredients.

Redesigning glycolaldehyde synthase for the synthesis of biorefinery feedstock D-xylulose from C1 compounds.

Global climate deterioration intensifies the demand for exploiting efficient CO2 utilization approaches. Converting CO2 to biorefinery feedstock affords an alternative strategy for third-generation biorefineries. However, upcycling CO2 into complex chiral carbohydrates remains a major challenge. Previous attempts at sugar synthesis from CO2 either produce mixtures with poor stereoselectivity or require ATP as a cofactor. Here, by redesigning glycolaldehyde synthase, the authors constructed a synthetic pathway for biorefinery feedstock D-xylulose from CO2 that does not require ATP as a cofactor. The artificial D-xylulose pathway only requires a three-step enzyme cascade reaction to achieve the stereoselective synthesis of D-xylulose at a concentration of 1.2gL-1. Our research opens up an alternative route toward future production of chemicals and fuels from CO2.

Improved prediction of biomass gasification models through machine learning

Gasification of lignocellulosic biomass can be used to produce syngas used as a biorefinery feedstock. To facilitate the commercialisation of the gasification process, models are used to predict the outputs, simulate the impacts of irregular circumstances, and analyse process feasibility. This paper presents a hybrid model combining Aspen Plus and machine learning (ML) algorithms to enhance the prediction of gasification outputs. A base case gasification process flowsheet simulation was implemented in Aspen Plus based on assumed thermodynamic equilibrium conditions which can lead to inaccurate results. To address this, six ML algorithms were applied to collected experimental data and analysed for accuracy and efficiency. The feature importance, accuracy improvement, and the effect of implementing the ML predictions in the gasification block on the rest of the flowsheet were investigated. This paper emphasises the need of higher accuracy models and the great potential of ML approaches to offer high accurate predictions.

Algal biomass based bio-refineries: Concurrent pre-treatment strategies and perspectives for sustainable feedstock

The quest for viable and scalable biofuel sources has been at the forefront of scientific innovation for the past three decades. Due to its rich chemical constituents, microalgal biomass has emerged as a pivotal sustainable and scalable feedstock for biorefineries. This comprehensive review critically analyzes the different types of microalgae feedstock, concurrent extraction technologies, bio-pre-treatment procedures, and the key chemical and physical parameters influencing lipid formation and algal biofuel production. We propose a novel approach of photo-initiated culturing of algal biomass using photobioreactors (PBRs) to address the limitations of concurrent space and time-related constraints. The innovative photo bio-refinery strategy presented herein aims to enhance sustainability factors while minimizing emissions, catering to the needs of futuristic non-electric vehicles. A comparative quality analysis of microalgae-derived biofuel against conventional fossil fuels and other biofuels is conducted, considering chemical, environmental, economic, and social perspectives. Furthermore, we elucidate the efficacy of bio-pre-treatment strategies such as dehydration, hydrothermal liquefaction, pyrolysis, and gasification in optimizing biofuel production. The proposed photo biorefineries exhibit the potential to yield a diverse range of value-added products, including biodiesel, biogases, bio-fertilizers, bio-pesticides, bio-alcohols, dyes, proteins, carotenoids, and drug vitals. This review provides a comprehensive framework for the development of sustainable and efficient microalgae-based biorefineries, paving the way for a greener and more economically viable future in the biofuel industry.

Toward an Environmentally Friendly Future: An Overview of Biofuels from Corn and Potential Alternatives in Hemp and Cucurbits

Increased energy consumption and climate change, driven by greenhouse gas emissions, pose significant risks to global sustainability. Concerns about using agricultural land for fuel production and its competition with food production have made feedstocks like corn (Zea mays) highly controversial. This study explores the potential of alternative feedstocks, such as hemp (Cannabis sativa) and cucurbits (family Cucurbitaceae), for biofuel production amidst environmental concerns linked to fossil fuel usage. Hemp is widely acknowledged as a promising feedstock for sustainable biorefinery due to its agricultural adaptability and its ability to produce oil and carbohydrates. Cucurbits seeds are characterized by a high oil content, which can be utilized in the food industry or for energy production as biofuel. As a byproduct of cucurbits processing, a significant number of seeds often remains, which constitutes waste. By examining hemp and cucurbit byproducts and waste, which are suitable for bioenergy production, this research highlights the promise these alternative feedstocks hold for the biofuel industry. Utilizing these resources presents a viable route to diminish dependence on fossil fuels and transition toward a more environmentally sustainable energy future.

Upcycling fruit waste into microalgae biotechnology: Perspective views and way forward

Fruit and vegetable wastes are linked to the depletion of natural resources and can pose serious health and environmental risks (e.g. eutrophication, water and soil pollution, and GHG emissions) if improperly managed. Current waste management practices often fail to recover high-value compounds from fruit wastes. Among emerging valorization methods, the utilization of fruit wastes as a feedstock for microalgal biorefineries is a promising approach for achieving net zero waste and sustainable development goals. This is due to the ability of microalgae to efficiently sequester carbon dioxide through photosynthesis, utilize nutrients in wastewater, grow in facilities located on non-arable land, and produce several commercially valuable compounds with applications in food, biofuels, bioplastics, cosmetics, nutraceuticals, pharmaceutics, and various other industries. However, the application of microalgal biotechnology towards upcycling fruit wastes has yet to be implemented on the industrial scale due to several economic, technical, operational, and regulatory challenges. Here, we identify sources of fruit waste along the food supply chain, evaluate current and emerging fruit waste management practices, describe value-added compounds in fruit wastes, and review current methods of microalgal cultivation using fruit wastes as a fermentation medium. We also propose some novel strategies for the practical implementation of industrial microalgal biorefineries for upcycling fruit waste in the future.

Conversion of N-doped biochar from carotenoid-extracted Tetraselmis suecica and its application to produce supercapacitors

Microalgae are one of the promising feedstocks for biorefinery, contributing significantly to net-zero emissions through carbon capture and utilization. However, the disposal of microalgal byproducts from the manufacturing process causes additional environmental pollution, thus, a new application strategy is required. In this study, the Tetraselmis suecica byproduct from the carotenoid extraction process was carbonized and converted into biochar. The converted biochar was proved to be nitrogen-doped biochar (NDB), up to 4.69%, with a specific surface area of 206.59 m2/g and was used as an electrode for a supercapacitor. The NDB electrode (NDB-E) in half-cell showed a maximum specific capacitance of 191 F/g. In a full-cell test, the NDB-E exhibited a high energy density of 7.396 Wh/kg and a high-power density of 18,100 W/kg, and maintained specific capacity of 95.5% after charge and discharge of 10,000 cycles. In conclusion, our study demonstrated that the carotenoid-extracted microalgal byproducts are a useful resource for the supercapacitor production. This approach is the first to convert T. suecica into active materials for supercapacitors.

Improved recovery of antioxidants from aronia juice processing residue via optimization of extraction variables based on multi-prediction models

Aronia melanocarpa, which has attracted attention for its outstanding antioxidant activity, is usually consumed as a juice, leaving considerable residue after processing into beverages. Recycling these by-products as feedstock for biorefineries is an important strategy for achieving a sustainable circular economy through biowaste management. In this study, the optimal extraction conditions for efficient antioxidant recovery from A. melanocarpa juice-processing residue (AJPR) were determined using statistical methods. Based on the Plackett-Burman design (PBD), four variables (shaking speed, solid loading, ethanol concentration, and total volume) were found to have significant effects on antioxidant extraction. The optimum points of the selected four variables were calculated by multi-regression models from response surface methodology (RSM), and the determined conditions were as follows:196.2 rpm, 71.3 g/L, 54.3% ethanol, and 137.8 mL of total volume. The DPPH• IC50 and ABTS•+ TEAC value of AJPR extracts were determined to be 2.02 mg/mL and 11.49 mg/mL, respectively, exhibiting promising potential as an antioxidant. The recovered polyphenol, flavonoid, and anthocyanin contents were 80.4, 42.5, and 14.1 mg/g-biomass, respectively. We show that bioengineering technologies can be used to achieve a circular economy by recycling discarded biowaste into value-added substances.

Ecological insights and environmental threats of invasive alien plantChromolaena odorata: Prospects for sustainable management

AbstractThe Anthropocene witnessed the landscape spread of several invasive alien plants which can remarkably influence the ecosystem services and environmental sustainability. To this end,Chromolaena odorata(Asteraceae) is widely identified among top hundred pervasive invaders in view of its adverse influence on environment, agriculture, and wildlife. The adverse effects ofC. odoratacan further be exacerbated under the event of invasion interaction with other anthropogenic stressors such as climate change. Nevertheless, there exists dearth of pragmatic studies on invasion ecology, socio‐economic impacts, ecological economics, and sustainable management prospects ofC. odorata. The present review discusses the invasion ecology, distribution, mechanisms, impacts, and management strategies ofC. odoratainvasion. The side‐effects and unsustainable use of traditional control measures (e.g., controlled fire and chemical herbicides) ofC. odoratapaves the way to biological control methods (e.g., gall fly). However, the control measures ofC. odorataneed to be assessed for their long‐term ecosystem level effects to mitigate the possible adverse environmental responses. The wise application ofC. odoratabiomass in marginal lands for soil fertility restoration, biosorption, biorefinery, bio‐medicine, and bioenergy in conjunction with ecological control measures can cover economic incentive to facilitate sustainable management ofC. odoratain forestry/agroforestry systems. Nevertheless, the use of weed biomass as feedstock in biorefinery and ethno‐medicine may be inadequate in reducing its invasion. Future studies should explicitly elucidate the ecological mechanisms ofC. odoratain concert with the quest for its field‐scale application in biorefinery to augment sustainable management.

Defibrillated Lignocellulose Recovery Guided by Plant Chemistry and Anatomy – A Pioneering Study with Lupinus angustifolius

AbstractThe strive toward sustainability increases the demand for bio‐based material production, forcing expansion of the biorefinery feedstock supply from forest wood to non‐woody materials such as agricultural residues. As a model organism for legume crops, the aptness of agricultural lupins as a lignocellulose feedstock is investigated. Principle chemical analysis combined with optotracing, in which the fluorescent tracer molecule Carbotrace 680 generates a visual map of the native tissues’ lignocellulose anatomy at sub‐cellular resolution, enables informed design of a mild recovery process. A streamlined conversion approach is then designed, yielding lignin‐containing microfibrillated cellulose. By monitoring defibrillation and delignification throughout the extraction process, the use of optotracing for non‐destructive fiber analytics at unprecedented details across all hierarchical structures of lignocellulosic materials is demonstrated. This crop valorization is a prime illustration of a holistic use of lupin biomass, with seeds serving as plant‐based food sources, and other parts as sources for lignocellulose‐based materials, thereby expanding both the biorefinery concept and feedstock supply.

Component analysis and utilization strategy of brown macroalgae as promising feedstock for sugar platform-based marine biorefinery

Component analysis and utilization strategy of brown macroalgae as promising feedstock for sugar platform-based marine biorefinery

Optimizing bioconversion processes of rice husk into value-added products: D-psicose, bioethanol, and lactic acid

Rice husk, rich carbon content, is an agricultural waste produced globally at an amount of 120 million tons annually, and it has high potential as a biorefinery feedstock. Herein, we investigated the feasibility of producing various products as D-psicose, bioethanol and lactic acid from rice husk (RH) through a biorefinery process. Alkali-hydrogen peroxide-acetic acid pretreatment of RH effectively removed lignin and silica, resulting in enzymatic hydrolysis yield of approximately 86.3% under optimal hydrolysis conditions. By using xylose isomerase as well as D-psicose-3-epimerase with borate, glucose present in the RH hydrolysate was converted into D-psicose with a 40.6% conversion yield in the presence of borate. Furthermore, bioethanol (85.4%) and lactic acid (92.5%) were successfully produced from the RH hydrolysate. This study confirmed the high potential of RH as a biorefinery feedstock, and it is expected that various platform chemicals and value-added products can be produced using RH.

Direct and robust citramalate production from brown macroalgae using fast-growing Vibrio sp. dhg

Brown macroalgae is a promising feedstock for biorefinery owing to its high biomass productivity and contents of carbohydrates such as alginate and mannitol. However, the limited availability of microbial platforms efficiently catabolizing the brown macroalgae sugars has restricted its utilization. In this study, the direct production of citramalate, an important industrial compound, was demonstrated from brown macroalgae by utilizing Vibrio sp. dhg, which has a remarkably efficient catabolism of alginate and mannitol. Specifically, citramalate synthase from Methanocaldococcus jannaschii was synthetically expressed, and competing pathways were removed to maximally redirect the carbon flux toward citramalate production. Notably, a resulting strain, VXHC, produced citramalate up to 9.8 g/L from a 20 g/L mixture of alginate and mannitol regardless of their ratios. Citramalate was robustly produced even when diverse brown macroalgae were provided directly. Collectively, this study showcased the high potential of brown macroalgae biorefinery using Vibrio sp. dhg.