Bio-based Chemicals Research Articles

Composition of Lignocellulose Hydrolysate in Different Biorefinery Strategies: Nutrients and Inhibitors

The hydrolysis and biotransformation of lignocellulose, i.e., biorefinery, can provide human beings with biofuels, bio-based chemicals, and materials, and is an important technology to solve the fossil energy crisis and promote global sustainable development. Biorefinery involves steps such as pretreatment, saccharification, and fermentation, and researchers have developed a variety of biorefinery strategies to optimize the process and reduce process costs in recent years. Lignocellulosic hydrolysates are platforms that connect the saccharification process and downstream fermentation. The hydrolysate composition is closely related to biomass raw materials, the pretreatment process, and the choice of biorefining strategies, and provides not only nutrients but also possible inhibitors for downstream fermentation. In this review, we summarized the effects of each stage of lignocellulosic biorefinery on nutrients and possible inhibitors, analyzed the huge differences in nutrient retention and inhibitor generation among various biorefinery strategies, and emphasized that all steps in lignocellulose biorefinery need to be considered comprehensively to achieve maximum nutrient retention and optimal control of inhibitors at low cost, to provide a reference for the development of biomass energy and chemicals.

Rapid fractionation of corn stover by microwave-assisted protic ionic liquid [TEA][HSO4] for fermentative acetone–butanol–ethanol production

BackgroundThe use of ionic liquids (ILs) to fractionate lignocelluloses for various bio-based chemicals productions is in the ascendant. On this basis, the protic ILs consisting of triethylammonium hydrogen sulfate ([TEA][HSO4]) possessed great promise due to the low price, low pollution, and high efficiency. In this study, the microwave-assistant [TEA][HSO4] fractionation process was established for corn stover fractionation, so as to facilitate the monomeric sugars production and supported the downstream acetone–butanol–ethanol (ABE) fermentation.ResultsThe assistance of microwave irradiation could obviously shorten the fractionation period of corn stover. Under the optimized condition (190 W for 3 min), high xylan removal (93.17 ± 0.63%) and delignification rate (72.90 ± 0.81%) were realized. The mechanisms for the promotion effect of the microwave to the protic ILs fractionation process were ascribed to the synergistic effect of the IL and microwaves to the depolymerization of lignocellulose through the ionic conduction, which can be clarified by the characterization of the pulps and the isolated lignin specimens. Downstream valorization of the fractionated pulps into ABE productions was also investigated. The [TEA][HSO4] free corn stover hydrolysate was capable of producing 12.58 g L−1 of ABE from overall 38.20 g L−1 of monomeric sugars without detoxification and additional nutrients supplementation.ConclusionsThe assistance of microwave irradiation could significantly promote the corn stover fractionation by [TEA][HSO4]. Mass balance indicated that 8.1 g of ABE and 16.61 g of technical lignin can be generated from 100 g of raw corn stover based on the novel fractionation strategy.

Simultaneous geraniol and citronellol transesterification using Pseudomonas fluorescens lipase for the production of fragrance and flavour esters: A kinetic study

This study aims to develop, for the very first time, a kinetic model for the simultaneous transesterification of geraniol and citronellol using Pseudomonas fluorescens lipase to produce their respective esters. This allows us to test the feasibility of the bioprocess and comprehend the enzyme behaviour, fine-tune process efficiency, and predict process performance. Geranyl and citronellyl esters are key ingredients in fragrance and flavour formulations in the food sector, as well as bioactive compounds for pest and insect repellents in the agricultural sector. Unlocking a greener and sustainable production of these terpene esters directly from plant-derived essential oil is crucial to meet the 2050 net zero targets to produce bio-based chemicals. The simultaneous transesterification of geraniol and citronellol in a batch reactor successfully achieved conversions of 66 % for citronellol and 94 % for geraniol within 5 h. Key optimum conditions were 1:8 molar ratio (geraniol:vinyl acetate), an enzyme loading of 10 wt % of geraniol, temperature of 40 °C, and a stirring speed of 250 RPM. The results indicated that simultaneous transesterification followed a ternary complex mechanism with competitive inhibition by alcohol. Initial testing of rose geranium oil under optimised conditions yielded 32 % citronellol and 50 % geraniol conversion after 30 h. Overall, this study shows promise as a green pathway utilising enzyme catalysis to selectively produce esters from diverse terpene mixtures and can be extended to terpene alcohols derived from flower essential oils.

Enhancing the activity and succinyl-CoA specificity of 3-ketoacyl-CoA thiolase Tfu_0875 through rational binding pocket engineering

The 3-ketoacyl-CoA thiolase is the rate-limiting enzyme for linear dicarboxylic acids production. However, the promiscuous substrate specificity and suboptimal catalytic performance have restricted its application. Here we present both biochemical and structural analyses of a high-efficiency 3-ketoacyl-CoA thiolase Tfu_0875. Notably, Tfu_0875 displayed heightened activity and substrate specificity for succinyl-CoA, a key precursor in adipic acid production. To enhance its performance, a deep learning approach (DLKcat) was employed to identify effective mutants, and a computational strategy, known as the greedy accumulated strategy for protein engineering (GRAPE), was used to accumulate these effective mutants. Among the mutants, Tfu_0875N249W/L163H/E217L exhibited the highest specific activity (320% of wild-type Tfu_0875), the greatest catalytic efficiency (kcat/KM = 1.00 min−1mM−1), the highest succinyl-CoA specificity (KM = 0.59 mM, 28.1% of Tfu_0875) and dramatically reduced substrate binding energy (−30.25 kcal mol−1v.s. −15.94 kcal mol−1). A structural comparison between Tfu_0875N249W/L163H/E217L and the wild type Tfu_0875 revealed that the increased interaction between the enzyme and succinyl-CoA was the primary reason for the enhanced enzyme activity. This interaction facilitated rapid substrate anchoring and stabilization. Furthermore, a reduced binding pocket volume improved substrate specificity by enhancing the complementarity between the binding pocket and the substrate in stereo conformation. Finally, our rationally designed mutant, Tfu_0875N249W/L163H/E217L, increased the adipic acid titer by 1.35-fold compared to the wild type Tfu_0875 in shake flask. The demonstrated enzymatic methods provide a promising enzyme variant for the adipic acid production. The above effective substrate binding pocket engineering strategy can be beneficial for the production of other industrially competitive biobased chemicals when be applied to other thiolases.

A straightforward chemobiocatalytic route for one-pot valorization of glucose into 2,5-bis(hydroxymethyl)furan

Direct conversion of inexpensive biomass into value-added chemicals via furanic platform molecules is highly attractive. In this work, we present a straightforward chemobiocatalytic route for glucose valorization into 2,5-bis(hydroxymethyl)furan (BHMF) in one pot, with no purification of the intermediate 5-hydroxymethylfurfural (HMF). Six candidate alcohol dehydrogenase (ADH) genes were located from Meyerozyma guilliermondii SC1103, based on comparative transcriptome analysis and real-time quantitative polymerase chain reaction. An ADH (MgADH1) was identified upon evaluation of catalytic performances of recombinant Saccharomyces cerevisiae harboring candidate ADHs in HMF reduction. Soluble expression of the enzyme in S. cerevisiae was greatly enhanced by its codon optimization, leading to improved HMF tolerance (up to 400 mM). In a fed-batch process, the desired product of approximately 473 mM (60.5 g/L) was produced within 30 h by recombinant S. cerevisiae_MgADH1. A chemobiocatalytic route toward BHMF was constructed by merging CaCl2-mediated isomerization and dehydration with biocatalytic reduction with an overall yield of approximately 42%, starting from glucose. This work may pave the way for green manufacture of valuable biobased chemicals.

Towards greener approach: Techno-economic insights into formaldehyde bio production from a hybrid pine and mustard biomass combination

In an era marked by environmental crises and dwindling fossil resources, the need to revolutionize industrial processes for sustainability is paramount. Formaldehyde synthesis, a pivotal precursor in industries spanning polymers, resins, and textiles, stands at a critical juncture where innovation and necessity intersect. Conventional methods of formaldehyde production, despite their efficiency, remain tethered to non-renewable feedstocks and energy-intensive techniques, perpetuating ecological harm and resource constraints. This study explores eco-friendly pathways for formaldehyde production. Recent strides in bio-based chemistry enable the creation of formaldehyde from renewable biomass, reducing energy use and carbon emissions. Decentralized production with locally sourced biomass boosts supply chain resilience and community-centered sustainability. The research employs Aspen Plus® software to model a two-step process: gasification of a hybrid pine and mustard biomass blend to produce bio-methanol, followed by its oxidation into formaldehyde. Sensitivity analyses demonstrate temperature's impact on syngas composition, with higher temperatures favoring hydrogen production. The air-to-biomass ratio affects carbon dioxide content and energy content, crucial for efficient energy production. In formaldehyde synthesis, the air-to-methanol ratio significantly influences yield. Economically, formaldehyde bio- production shows promise, with an 8.50% return on investment and a 22.16-year payback period. An annual net profit of $2.41 million is projected, with a break-even point at $53.47 million in total sales revenue. This research underscores the convergence of sustainability, innovation, and economic viability in formaldehyde bio-production, offering valuable insights for environmentally friendly chemical manufacturing and the broader transition to ecological progress.

Green synthesis of solketal from glycerol using metal-modified ZSM-5 zeolite catalysts: process optimization.

This study investigates the production of solketal (2,2-dimethyl-1,3-dioxolane-4-methanol) from glycerol via ketalization reaction using M-ZSM-5 catalysts (M = Fe, Co, Ni, Cu, and Zn). The wet impregnation method ensured precise metal loading and versatility in catalyst preparation. We present a novel approach by employing a suite of characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), Thermogravimetric analysis (TGA), and Field-emission scanning electron microscopy (FE-SEM), to elucidate the catalyst's structure, bonding, surface area, thermal stability, and morphology, ultimately linking these properties to their performance. Solketal synthesis was optimized in a reactor, with parameters like temperature, glycerol:acetone molar ratio, catalyst amount, reaction time, and stirring speed. Optimal conditions were identified as 60°C, 1:4, 0.2g, 60min, and 1200rpm, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis confirmed successful solketal formation. Among M-ZSM-5 catalysts tested, Cu-ZSM-5 emerged the most efficient, achieving an impressive 99% glycerol conversion and 96% solketal selectivity. Notably, Cu-ZSM-5 catalyst displayed exceptional reusability, regaining its initial activity through calcination, thus minimizing waste generation. This research unveils Cu-ZSM-5 as a highly efficient catalyst and promotes sustainability by utilizing a renewable glycerol feedstock to produce valuable solketal with applications in fuel additives, solvents, and pharmaceuticals. This work paves the way for developing environmentally friendly processes for waste valorization and producing valuable bio-based chemicals.

Tolerance of hyperosmolar Candida krusei

The utilization of industrial microorganisms for the conversion of lignocellulose into high value-added chemicals is an essential pathway towards achieving carbon neutrality and promoting sustainable bioeconomy. However, the pretreated lignocellulase hydrolysate often contains various sugars, salts, phenols/aldehydes and other substances, which requires microorganisms to possess strong tolerance for direct fermentation. This study aims to investigate the tolerance of Candida krusei to substrate, salt, and high temperature shock, in order to validate its potential for utilizing the enzymatic hydrolysate of Pennisetum giganteum in seawater for fermentation. The experimental results showed that the adaptively domesticated C. krusei exhibited tolerance to glucose at a concentration of 200 g/L and became a hypertonic strain. When seawater was used instead of freshwater without sterilization, the yield of glycerol in fermentation was 109% higher than that in freshwater with sterilization. Moreover, the combined thermal shock at 32 hours of fermentation and addition of 10 Na2SO3 at 48 hours resulted in a yield of glycerol to glucose 0.37 g/g, which was 225% higher than the control group. By fermenting the enzymatic hydrolysate of P. giganteum pretreated in seawater, the total conversion rate of glucose into glycerol and ethanol reached 0.45 g/g. This study indicates that hypertonic C. krusei exhibits remarkable adaptability to substrate, salt, and temperature. It not only can directly utilize complex lignocellulosic hydrolysates, but also exhibits strong tolerance to them. Therefore, it provides a potential candidate strain for the production of bio-based chemicals using lignocellulosic processes.

Green Plasticizer for Poly(vinyl chloride) Re-Granulate Production: Case Study of Sustainability Concept Implementation

The increase in waste polymer recycling has helped in promoting sustainability, and together with the use of renewable raw materials, it has become a widespread concept with positive effects on both the economy and ecology. Accordingly, the aim of this study was the synthesis of “green” plasticizers, marked as LA/PG/PET/EG/LA, formed from waste poly(ethylene terephthalate) (PET) and bio-based platform chemicals propylene glycol (PG) and levulinic acid (LA). The structure of the obtained plasticizers was complex, as confirmed by results from nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR) analysis. The LA/PG/PET/EG/LA plasticizers and waste poly(vinyl chloride) (PVC) were used in an optimized technology for PVC re-granulate production. The hardness of the PVC-based material with “green” plasticizers, in comparison to commercial plasticizer dioctyl terephthalate (DOTP), increased by 11.3%, while migration decreased. An improved material homogeneity and wettability of the fibers by the matrix were observed using SEM analysis of the material’s fracture surface, with a higher efficiency of intermolecular interactions leading to better mechanical performances of the newly designed materials. Thus, LA/PG/PET/EG/LA are unique materials with good compounding and plasticizing potential for PVC, as revealed by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). In that manner, the use of bio-renewable resources and recycled polymers will contribute to diminishing waste polymer generation, contributing to a lower carbon footprint.

Enhancing bio-based chemical production and reducing pollutants emission through the synergistic effect of ZSM-5/CaO during hydrogen-deficient biomass pyrolysis

The study proposed the use of ZSM-5/CaO as a catalyst to simultaneously improve the quality of pyrolytic products and reduce pollutants emission during the pyrolysis of hydrogen-deficient biomass, specifically cabbage waste (CW). Variables such as pyrolysis temperature and catalysts, including 5% ZSM-5, 5% CaO and 10% ZSM-5/CaO, significantly affected biomass conversion, yield, and products composition. Thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) analysis shows that the catalysts (5% ZSM-5, 5% CaO and 10% ZSM-5/CaO) reduced pollutants emission and increased value-added chemicals production by 24.96%, 28.5%, 17.39% and 75.04%, 71.5%, 82.1%, respectively compared to non-catalytic process as 34.18% and 65.82%. Moreover, these catalysts enhanced the relative yield of olefins, aromatics, and phenols to 23.5, 21.6, 27.6% for 5wt.%ZSM-5; 20.8, 18.7, 23.3% for 5wt.%CaO; 30.7, 38.6, 41.3% for 10wt.%ZSM-5/CaO, compared to the non-catalytic process' yield of 15.7, 10.7, 19.3%. Py/GC–MS analysis confirms that these catalysts also decreased PAH and oxygenates production to 13.5, 15.3% for 5wt.%ZSM-5; 11.8, 9.1% for 5wt.%CaO; 5.2, 4.7% for 10wt.%ZSM-5/CaO, in contrast to the non-catalytic process' 26.2, 28.7%. This confirms the synergistic effect of ZSM-5/CaO for upgrading bio-based chemicals and reducing pollutants emission.

Advancements in Synthesis Strategies and Optoelectronic Applications of Bio-Based Photosensitive Polyimides

With the rapid development of information, energy, and materials industries in China, the demand for high-performance polymers is gradually increasing. Photosensitive polyimide (PSPI) has emerged as an ideal choice for high-performance optoelectronic materials due to its outstanding thermal stability, mechanical strength, and low dielectric constant. In particular, bio-based photosensitive polyimide prepared from bio-based chemicals, as a green polymer material, not only reflects the advantages of environmental protection and resource efficiency but also contributes to carbon neutrality. However, how to improve the photolithography efficiency while maintaining the thermodynamic performance and environmental friendliness and how to balance the pros and cons of low-molecular-weight matrixes are still challenges in the research. This review systematically summarizes the synthesis and performance characteristics of photosensitive polyimides, bio-based polyimide, and bio-based photosensitive polyimides and further explores the future application prospects of bio-based polyimides in the field of high-performance optoelectronic materials.

Effect of Calcination Temperature on Sulfonated Lignin Catalyst Preparation for Glucose Ethanolysis to Ethyl Levulinate

An abundance of biomass material is generated globally which has the potential to be converted to various bio-based chemicals including ethyl levulinate (EL). EL is well known as a sustainable fuel additive and can be produced from glucose, a biomass derivative in an ethanolysis reaction throughout acidic catalysis. In this study, sulfonated lignin carbon catalysts were used to catalyze the ethanolysis of glucose to synthesize EL. The catalysts were prepared from lignin via calcination at different soaking temperatures (400 to 600 °C) for 1 h to produce carbon material, followed by sulfonation with concentrated sulfuric acid at a 1:10 (carbon-to-acid, g/mL) ratio. The catalysts were tested for glucose ethanolysis reaction in a batch reactor equipped with a thermocouple on selected conditions (0.4 g of glucose, 40 mL of ethanol, 1.2 g of catalyst, and 6 h reaction) at 180 °C and their performance was evaluated according to the EL yield obtained. Then, the catalyst characterization was conducted for the selected catalyst using Fourier transform infrared spectroscopy (FTIR), ion-exchange titration, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), nitrogen sorption analysis, and Thermalgravimetric analysis (TGA). The result showed that the performance of the sulfonated lignin carbon catalysts was reduced, especially at higher soaking calcination temperatures. The catalyst prepared from lignin carbon calcined at 450 °C, (CS450) was able to provide a high EL yield of 22.54 mol% with a good acidity of 1.0 mmol/g, a high surface area of 229.95 m2/g, and suggested thermal stability at 300 °C. The results indicated that the sulfonated lignin carbon catalyst could be used as a solid acid catalyst for glucose ethanolysis reaction, yet further catalyst modification is required in the future to enhance its performance for higher EL yield.

Pyrolytic characteristics of abutilon stalk waste using TG-FTIR, Py-GC/MS, and artificial neural networks: Kinetics, thermodynamics, and gaseous products distribution

The physicochemical properties of abutilon stalk (ABUS) were investigated to assess its suitability for pyrolytic conversion into bioenergy and bio-based chemicals based on kinetic triplet state, thermodynamic parameters, decomposition mechanisms and product distributions. The pyrolysis behavior of ABUS was studied using a thermogravimetric analyzer at five heating rates in a nitrogen atmosphere. The Gaussian deconvolution function indicated that the pyrolysis process of ABUS can be successfully modeled as four parallel devolatilization events (R2 > 0.99), divided into the devolatilization of pseudo drying (PO-D), hemicellulose (PO-H), cellulose (PO-C), and lignin (PO-L), respectively. The average apparent activation energies were 34.89 kJ/mol for PO-D, 163.02 kJ/mol for PO-H, 169.55 kJ/mol for PO-C, and 107.51 kJ/mol for PO-L using four model-free methods (Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose, Starink, and Tang). The pyrolysis process was accurately predicted using diffusional, power law, geometrical contraction, and order-based reaction mechanism models. Thermal degradation process for each devolatilization event was successfully reconstructed using combined kinetics (R2 > 0.96), providing a useful theoretical basis and mathematical model for predicting the pyrolysis behavior of ABUS. The volatile products produced by ABUS pyrolysis were characterized using an integrated TGA-FTIR and Py-GC/MS system, confirming the proportion of high-energy compounds (benzenes, phenols, ketones, alcohols, aldehydes, acids, esters, hydrocarbons and their derivatives, N-heterocyclic substances, and N-containing compounds) and gas emission levels (CO > CH4 > C-O > H2O > CO2 > CO > C-O(H) > HCN > NH3 > SO2). Artificial neural network (ANN) was used to predict the pyrolysis behaviors of ABUS, and the best ANN model was ANN (5 *11 *1) with high R2 of 0.99998. Based on the kinetics, thermodynamics, and gaseous products distribution, ABUS has great application potential as raw material for bioenergy production.

Extraction of 5-Hydroxymethylfurfural and Furfural in Aqueous Biphasic Systems: A COSMO-RS Guided Approach to Greener Solvent Selection.

5-Hydroxymethylfurfural (HMF) and furfural (Fur) are promising biobased platform chemicals, derived from the dehydration of carbohydrate feedstocks, normally conducted in an aqueous phase. Plagued by side-reactions in such phase, such as the rehydration to levulinic acid (LA) and formic acid (FA) or self-condensation to humins, HMF and Fur necessitates diversification from monophasic aqueous reaction systems toward biphasic systems to mitigate undesired side-reactions. Here, a methodology based on the COnductor-like Screening MOdel for Real Solvents (COSMO-RS) method was used to screen solvent candidates based on the predicted partition coefficients (Ki). Hansen solubility parameters in conjunction with excess thermodynamic quantities determined by COSMO-RS were employed to assess solvent compatibility. Experimental validation of the COSMO-RS values highlighted only minor deviations from the predictions with root-mean-square-error (RMSE) values of HMF and Fur at 0.76 and 5.32, respectively, at 298 K. The combined effort suggested cyclohexanone, isophorone, and methyl isobutyl ketone (MIBK) as the best candidates. Finally, extraction solvent reuse demonstrated cyclohexanone suitability for HMF extraction with KHMF of 3.66 and MIBK for Fur with KFur 7.80 with consistent partitioning across four total runs. Both solvents are classified as recommended by the CHEM21 solvent selection guide, hence adding to the sustainability of the process.

Zymochem gets cash for biobased chemicals

Zymochem gets cash for biobased chemicals

Acyclic Diene Metathesis (ADMET) Polymerization for the Synthesis of Chemically Recyclable Bio-Based Aliphatic Polyesters

The recent developments of the synthesis of bio-based long-chain aliphatic polyesters by the acyclic diene metathesis (ADMET) polymerization of α,ω-dienes, derived from plant oils and bio-based chemicals, like bis(10-undecenoate) with isosorbide, using ruthenium-carbene catalysts are reviewed. The development of subsequent (one-pot) tandem hydrogenation produced saturated polyesters under mild conditions. The polymerizations under bulk (without solvent, 80–90 °C) or in ionic liquids (50 °C) under vacuum conditions enabled the synthesis of high molar mass polymers (Mn > 30,000 g/mol). The polymerization performed by the molybdenum-alkylidene catalyst afforded the highest-molecular-weight polyesters (44,000–49,400 g/mol, in toluene at 25 °C) exhibiting promising tensile properties (strength and elongation at break) compared to polyethylene and polypropylene. Depolymerizations of these polyesters, including closed-loop chemical recycling, were also demonstrated. Catalyst developments (more active, under mild conditions) play a key role in the efficient synthesis of these materials.

Production of Biobased Ethylbenzene by Cascade Biocatalysis with an Engineered Photodecarboxylase.

Production of commodity chemicals, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), from renewable resources is key for a sustainable society. Biocatalysis enables one-pot multistep transformation of bioresources under mild conditions, yet it is often limited to biochemicals. Herein, we developed a non-natural three-enzyme cascade for one-pot conversion of biobased l-phenylalanine into ethylbenzene. The key rate-limiting photodecarboxylase was subjected to structure-guided semirational engineering, and a triple mutant CvFAP(Y466T/P460A/G462I) was obtained with a 6.3-fold higher productivity. With this improved photodecarboxylase, an optimized two-cell sequential process was developed to convert l-phenylalanine into ethylbenzene with 82 % conversion. The cascade reaction was integrated with fermentation to achieve the one-pot bioproduction of ethylbenzene from biobased glycerol, demonstrating the potential of cascade biocatalysis plus enzyme engineering for the production of biobased commodity chemicals.

Herstellung von biobasiertem Ethylbenzol durch Kaskaden‐Biokatalyse mit einer speziell entwickelten Photodecarboxylase

AbstractDie Herstellung von chemischen Grundstoffen wie Benzol, Toluol, Ethylbenzol und Xylol (BTEX) aus erneuerbaren Ressourcen ist der Schlüssel zu einer nachhaltigen Gesellschaft. Die Biokatalyse ermöglicht die Ein‐Topf‐Mehrschritt‐Transformation von Bioressourcen unter milden Bedingungen, ist jedoch oft auf Biochemikalien beschränkt. Wir haben eine nicht‐natürliche Drei‐Enzym‐Kaskade für die Ein‐Topf‐Umwandlung von biobasiertem l‐Phenylalanin in Ethylbenzol entwickelt. Die geschwindigkeitsbestimmende Photodecarboxylase als Schlüsselenzym wurde einem strukturbasierten semi‐rationalem Engineering unterzogen und es wurde eine Dreifachmutante CvFAP(Y466T/P460A/G462I) mit einer 6.3‐fach höheren Produktivität erhalten. Mit dieser verbesserten Photodecarboxylase wurde ein optimiertes sequentielles E. coli Zwei‐Zellsystem‐Verfahren zur Umwandlung von l‐Phenylalanin in Ethylbenzol mit 82 % Umsatz entwickelt. Die Kaskadenreaktion wurde in die Fermentation integriert, um eine Ein‐Topf‐Bioproduktion von Ethylbenzol aus biobasiertem Glycerin zu erreichen. Dies zeigt das Potenzial der Kaskaden‐Biokatalyse in Kombination mit einem Enzym‐Engineering für die Produktion von biobasierten chemischen Grundstoffen auf.

Integrated acetic acid and deep eutectic solvent pretreatment on poplar for co-production of xylo-oligosaccharides, fermentable sugars and lignin antioxidants/adsorbents

Efficient fractionation of lignocellulosic biomass in usable forms of hemicellulose, cellulose and lignin is very important for the sustainable lignocellulosic biorefinery. Herein, poplar sawdust was pretreated with an integrated process composed of acetic acid pre-hydrolysis (170 °C, 60 min) for xylo-oligosaccharides (XOS) production and mild deep eutectic solvent (90–130 °C, 60 min) post-delignification for recovering lignin fractions, resulting in easily hydrolyzed cellulose fraction. Results showed that, after integrated pretreatment and enzymatic hydrolysis, 51 % of xylan and 92 % of glucan in raw biomass could be converted to XOS (DP 2–6) and glucose, respectively, while 71 % of the original lignin could be recovered in DES solvent. The resulting XOS were proven to ensure the growth of probiotics, Bifidobacterium adolescentis. Besides, the lignin macromolecules recovered from DES solvent showed high-purity (around 95 %), low-molecular weight (Mw around 2000), small particle size (270–170 nm) and high-PhOH (3.08 mmol/g) content, which were likely relevant to the excellent antioxidant activity (RSI = 15.16) and adsorbent activity (Pb(II) 461.89 mg/g lignin). Finally, mass balance and energy analysis revealed that the integrated pretreatment could be used as a promising approach for the production of bio-based chemicals and materials from woody biomass.

Highly efficient production of 2,3-pentanedione from condensation of bio-derived lactic acid over polymorphic ZrO2

The demand for fermentation-based chemicals is expected to grow in the coming years because of the increasing emphasis on using bio-based chemicals over petrochemicals.