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Recently, highly efficient production of furfural from available, abundant, inexpensive, and renewable lignocellulosic biomass has gained much attention by using biomass-based heterogeneous catalyst in an effective biphasic system. Using microwave-treated chestnut shell (MC-CNS) as biobased support, biomass-based catalyst (MC-Sn-CNS) was firstly synthesized for catalyzing biomass into furfural. The structure parameters of MC-Sn-CNS were measured by BET, SEM, XRD, and FT-IR. After systematical optimization, furfural yield reached 64.4% from corncob by MC-Sn-CNS (3.6 wt%) at 180 °C for 15 min in methyl isobutyl ketone (MIBK)–water (2:1, v:v) containing 200 mM NaCl. MC-Sn-CNS had high stability, which could be recycled for 7 batches. The yield of furfural from fresh corncob was 44.5–64.4%. The possible catalytic mechanism for synergistic catalysis of biomass to furfural by MC-Sn-CNS was expounded in MIBK–water–NaCl system. The results showed that green solvent (MIBK) and NaCl promoted the production of furfural from CC catalyzed by solid acid (MC-Sn-CNS). This study demonstrated an environmentally friendly strategy for efficiently utilizing corncob into furfural by CNS-based heterogeneous chemocatalyst in a green reaction media. Clearly, this newly synthesized biomass-based MC-Sn-CNS catalyst had potential application in the future.

In this research, the biochar-based tin-loaded heterogeneous catalyst Sn-NUS-BH was used for the efficient catalytic conversion of corncob (CC) in a green biphasic system of cyclopentyl methyl ether–water (CPME-H2O). By optimizing the system conditions (CPME to H2O ratio, Sn-NUS-BH dosage, reaction time, and reaction temperature), the stubborn structure of corncobs was maximally disrupted. The chemical composition and structural characteristics (accessibility, lignin surface area, and hydrophobicity) of CC before and after treatment were assessed, demonstrating that the natural physical barriers of CC were disrupted and lignin was effectually eliminated. The accessibility was enhanced from 137.5 mg/g to 518.5 mg/g, the lignin surface area declined from 588.0 m2/g to 325.0 m2/g, and the hydrophobicity was changed from 4.7 L/g to 1.3 L/g. Through the treatment at 170 °C for 20 min, furfural (11.7 g/L) and xylooligosaccharides (4.5 g/L) were acquired in pretreatment liquor. The residual CC could be enzymatically saccharified into reducing sugars in a yield of 65.2%. The combination pretreatment with the tin-based biochar chemocatalyst Sn-NUS-BH combined with the green solvent system CPME-H2O shows great promise in the valorization of biomass.

In this study, chemoenzymatic synthesis of furfuryl alcohol from biomass (e.g., corncob, bamboo shoot shell, and rice straw) was attempted by the tandem catalysis with Lewis acid (SnCl4 or solid acid SO42−/SnO2-bentonite) and biocatalyst in one-pot manner. Compared with SnCl4, solid acid SO42−/SnO2-bentonite had higher catalytic activity for converting biomass into furfural, which could be biologically converted into furfuryl alcohol with Escherichia coli CCZU-H15 whole-cell harboring reductase activity. Sequential catalysis of biomass into furfural with SO42−/SnO2-bentonite (3.0 wt%) at 170 °C for 0.5 h and bioreduction of furfural with whole cells at 30 °C for 4.5 h were used for the effective synthesis of furfuryl alcohol in one-pot media. Corncob, bamboo shoot shell, and rice straw (3.0 g, dry weight) could be converted into 65.7, 50.3, and 58.5 mM furfuryl alcohol with the yields of 0.26, 0.25, and 0.23 g furfuryl alcohol/(g xylan in biomass) in 40 mL reaction media. Finally, an efficient process of recycling and reusing of SO42−/SnO2-bentonite catalyst and immobilized whole-cell biocatalyst was developed for the chemoenzymatic synthesis of furfuryl alcohol from biomass in the one-pot reaction system.

In this work, an effective hybrid strategy was developed for tandem conversion of biomass to furfurylamine with tin-based solid acid Sn-Maifanitum stone and recombinant Escherichia coli whole cells harboring ω-transaminase. 90.3 mM furfural was obtained from corncob (75 g/L) at 170 °C for 0.5 h over Sn-Maifanitum stone catalyst (3.5 wt%) in the aqueous media (pH 1.0), which could be further bioconverted into furfurylamine at 74.0% yield (based on biomass-derived furfural) within 20.5 h. Finally, an efficient recycling and reuse of Sn-Maifanitum stone catalyst and immobilized Escherichia coli AT2018 whole-cell biocatalyst was developed for the synthesis of furfurylamine from biomass in the one-pot reaction system.

The objective of this work was to develop an efficient approach for chemoenzymatically transforming biomass to furfurylamine by bridging chemocatalysis and biocatalysis in a deep eutectic solvent of EaCl:Gly–water. Using hydroxyapatite (HAP) as support, heterogeneous catalyst SO 4 2− /SnO 2 –HAP was synthesized for transforming lignocellulosic biomass into furfural using organic acid as a co-catalyst. The turnover frequency (TOF) was correlated with the pKa value of the used organic acid. Corncob was transformed by oxalic acid (pKa = 1.25) (0.4 wt%) plus SO 4 2− /SnO 2 –HAP (2.0 wt%) to produce furfural with a yield of 48.2% and a TOF of 6.33 h -1 in water. In deep eutectic solvent EaCl:Gly–water (1:2, v/v), co-catalysis with SO 4 2− /SnO 2 –HAP and oxalic acid was utilized to transform corncob, rice straw, reed leaf, and sugarcane bagasse for the production of furfural with the yield of 42.4%–59.3% (based on the xylan content) at 180°C after 10 min. The formed furfural could be efficiently aminated to furfurylamine with E. coli CCZU-XLS160 cells in the presence of NH 4 Cl (as an amine donor). As a result of the biological amination of furfural derived from corncob, rice straw, reed leaf, and sugarcane bagasse for 24 h, the yields of furfurylamine reached >99%, with a productivity of 0.31–0.43 g furfurylamine per g xylan. In EaCl:Gly–water, an efficient chemoenzymatic catalysis strategy was employed to valorize lignocellulosic biomass into valuable furan chemicals.

Abstract Recently, highly efficient production of valuable furan-based chemicals from available and renewable lignocellulosic biomass has attracted more and more attention via a chemoenzymatic route in an environmentally friendly reaction system. In this work, the feasibility of chemoenzymatically catalyzing sugarcane bagasse into furfurylamine with heterogeneous catalyst and ω-transaminase biocatalyst was developed in the deep eutectic solvent (DES) ChCl:Gly–water. Sulfonated Al-Laubanite was firstly synthesized to catalyze sugarcane bagasse to furfural. SEM, BET, XRD, and FT-IR were used to characterize Al-Laubanite. Catalyst Al-Laubanite structure was significantly different from carrier laubanite. High furfural yield (60.9%) was achieved by catalyzing sugarcane bagasse in 20 min at 170 ℃ and pH 1.0 by Al-Laubanite (2.4 wt%) in the presence of ChCl:Gly (20 wt%). Potential catalytic mechanism was proposed under the optimized catalytic condition. In addition, one recombinant E. coli CV harboring ω-transaminase could completely transform biomass-derived furfural to furfurylamine at 40 °C and pH 7.5 using L-alanine as amine donor in ChCl:Gly–water (20:80, wt:wt). This established chemoenzymatic cascade reaction strategy was successfully utilized for valorization of biomass into furan-based chemicals in the benign ChCl:Gly–water system.

Furfurylamine is an important furfural-upgrading biobased chemical for the production of pharmaceuticals, biofuels, fibers, additives, polymers, etc. In one-pot reaction system, biomass was tandemly catalyzed to furfurylamine with aluminium-based alkaline-treated graphite (Al-AG) catalyst and recombinant ω-transaminase biocatalyst. Al-AG (3.6 wt%) catalyzed corncob (75.0 g/L) to 110.0 mM furfural at 56.8% yield (based on xylan in corncob) in γ-valerolactone–water (1:4, v:v; pH 1.0) for 40 min at 180 °C. The pH-adjusted corncob-slurry (pH 7.5) containing furfural were catalyzed to furfurylamine at high yield with γ-valerolactone-tolerant Aspergillus terreus ω-transaminase biocatalyst at 35 °C using isopropylamine (3 mol isopropylamine/mol furfural) as amine donor. Such an efficient and sustainable approach for catalytic conversion of biomass to high-value-added biobased furfurylamine was successfully established in tandem reaction with Al-AG and ω-transaminase biocatalyst. Graphic Abstract

Heterogeneous tin-based sulfonated graphite (Sn-GP) catalyst was prepared with graphite as carrier. The physicochemical properties of Sn-GP were captured by FT-IR, XRD, SEM and BET. Organic acids with different pKa values were used to assist Sn-GP for transforming corncob (CC), and a linear equation (Furfural yield  = − 7.563 ×  pKa  + 64.383) (R2  =  0.9348) was fitted in acidic condition. Using sugarcane bagasse, reed leaf, chestnut shell, sunflower stalk and CC as feedstocks, co-catalysis of CC (75.0 g/L) with maleic acid (pKa  =  1.92) (0.5 wt%) and Sn-GP (3.6 wt%) yielded the highest furfural yield (47.3%) for 0.5 h at 170 °C. An effective furfural synthesis was conducted via co-catalysis with Sn-GP and maleic acid. Subsequently, E. coli CG-19 and TS completely catalyzed the conversion of corncob-derived FAL to furfurylalcohol and furoic acid, respectively. Valorisation of available renewable biomass to furans was successfully developed in tandem chemoenzymatic reaction.

Gastrodin is a bioactive component of traditional Chinese medicine, exhibiting anti-cancer, anti-inflammatory, antioxidant and neuroprotective properties. It has broad application prospects in health foods, pharmaceuticals and cosmetics. In recent years, the conversion of biomass-derived aldehydes into high-value-added chemicals has garnered widespread attention. In this study, gastrodin was biosynthesized via a dual-enzyme coupling system consisting of UGTBL1-Δ60 and KpADH. Specifically, lignin-derived p-hydroxybenzaldehyde was used as the substrate. First, the glycosylation of p-hydroxybenzaldehyde by UGTBL1-Δ60 yielded p-hydroxybenzaldehyde β-glucoside, generating the glycosylation reaction solution. Subsequently, bioreduction of the glycosylation product by KpADH produced gastrodin. Under the optimal reaction conditions (0.05 g/mL KpADH whole cells, 50 mM glucose, pH 7.5 and 30 °C) a gastrodin yield of 82.8% was achieved within 12 h. Moreover, both UGTBL1-Δ60 and KpADH retained high catalytic activity after multiple reaction cycles. This study establishes a green and efficient biocatalytic approach for gastrodin synthesis, and also provides new insights into the high-value utilization of lignin.

Circular RNAs (circRNAs) are endogenous noncoding RNAs (ncRNAs) with transcriptional lengths ranging from hundreds to thousands. circRNAs have attracted attention owing to their stable structure and ability to treat complicated diseases. Our objective was to create a one-step reaction for circRNA synthesis using wild-type T7 RNA polymerase as the catalyst. However, T7 RNA polymerase is thermally unstable, and we streamlined circRNA synthesis via consensus and folding free energy calculations for hotspot selection. Because of the thermal instability, the permuted intron and exon (PIE) method for circRNA synthesis is conducted via tandem catalysis with a transcription reaction at a low temperature and linear RNA precursor cyclization at a high temperature. To streamline the process, a multisite mutant T7 RNA polymerase (S430P, N433T, S633P, F849I, F880Y, and G788A) with significantly improved thermostability was constructed, and G788A was used. The resulting mutant exhibited stable activity at 45°C for over an hour, enabling the implementation of a one-pot transcription and cyclization reaction. The simplified circRNA production process demonstrated an efficiency comparable to that of the conventional two-step reaction, with a cyclization rate exceeding 95% and reduced production of immunostimulatory dsRNA byproducts.