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Efficiently dissolving and separating cellulose from xylose residue is beneficial to realize the high added-value of lignocellulosic waste. In this work, theoretical prediction by using COSMO-RS and practical experiments were combined to investigate the extraction selectivity of ionic liquids (ILs) for cellulose and lignin. Two imidazolium-based ILs, 1-ethyl-3-methylimidazolium diethylphosphate ([Emim]DEP) and 1-allyl-3-methylimidazolium chloride ([Amim]Cl), were screened out from 425 ILs. These ILs were subsequently mixed with dimethyl sulfoxide (DMSO) to dissolve and separate cellulose from xylose residue. The cellulose extraction efficiency of [Emim]DEP/DMSO were optimized by regulating the content of xylose residue, dissolution temperature and time. As the cellulose content was 1.2 wt%, the dissolution temperature of 80 °C, and the dissolving time of 120 min, the cellulose extraction rate of xylose residue could reach as high as 99.3% in [Emim]DEP/DMSO, which is higher than that in [Amim]Cl/DMSO (95.4%). The higher cellulose and lower lignin dissolution capacities of [Emim]DEP indicated that [Emim]DEP was a promising solvent to realize the conversion and utilization of cellulose in agro-industrial residues. In addition, [Emim]DEP presents constant dissolution capacity even it was recycled for five times. Furthermore, the produced xylose residue cellulose film (XRCF) displayed a homogeneous and smooth morphology with a tensile strength of 55.9 MPa, which had great potential in packaging. • The theoretical extraction selectivity of ionic liquids for cellulose and lignin was investigated using COSMO-RS. • [Emim]DEP/DMSO system was screened out to efficiently separate cellulose from xylose residue by experimental conformation. • The cellulose extraction rate of xylose residue can reach as high as 99.3% in [Emim]DEP/DMSO system. • The prepared xylose residue cellulose film exhibited a homogeneous morphology with a tensile strength of 55.9 MPa. [ABSTRACT FROM AUTHOR]

• Acetate metabolic pathway via glyoxylate shunt in K. marxianus was revealed. • Enhanced glyoxylate shunt increased acetate metabolism to 122.7 % at 40 °C. • Overexpressing GPD2 and FDH1 further increased acetate uptake by 3.9 folds. • Toxic compounds detoxification enhanced lignocellulosic biomass conversion. • Foresight for the acetate utilization as an intermediate for reducing CO 2. Lignocellulosic biomass is a typical agriculture waste and a potential feedstock for the green biomanufacturing. However, insufficient utilization of carbon sources caused by inhibitors, especially acetic acid, hinders the economic bioconversion. Here, we demonstrated the acetate metabolic pathway via glyoxylate shunt in nonconventional yeast Kluyveromyces marxianus. Acetate metabolism increased to 122.7 % at 40 °C after overexpressing ICL1 and MLS1 , key genes of glyoxylate shunt revealed by transcriptomic data. Strengthening GPD2 and FDH1 further enhanced the robustness of the K. marxianus , acetate metabolism was significantly increased. Finally, the modified K. marxianus 1727–5-ICL1-MLS1-GPD2-FDH1 boosted the efficiency for xylose uptake up to 1.3 folds in non-detoxified lignocellulosic hydrolysate, benefiting from a 3.9-fold increase in acetate consumption. Our results propose a novel strategy for xylose assimilation by coupling acetate metabolism, contributing the bioconversion of sustainable lignocellulosic biomass. It also provides a new scheme for the total carbon utilization of lignocellulosic biomass, including carbon dioxide (CO 2) released from the biofuel production to achieve a circular economy. [ABSTRACT FROM AUTHOR]

The versatility of the pathway to produce polyols from sugars through catalytic transfer hydrogenation (CTH) using commercial Raney nickel catalysts and 1,4-butanediol as hydrogen source has been explored. The results reveal that the nickel purity of the catalyst is a key parameter in process selectivity and presents the CTH route as a promising alternative to conventional hydrogenation processes, effective for the complete valorization of the sugar platform, including hexoses, pentoses and disaccharides. The study uncovers a significant influence of sugar structure on the resulting reactions, with threo-configured sugars displaying enhanced selectivity, while erythro-configured sugars demonstrate elevated conversion rates and the production of a broader spectrum of sugar alcohol isomers. Furthermore, a computational study, using density functional theory (DFT) calculations, has been carried out to describe the performance of the disaccharides and correlate it with their activity in the reaction media. [Display omitted] • Catalytic transfer hydrogenation (CTH) is a versatile way to produce sugar alcohols. • Raney nickel excels performance in selective hydrogen transfer from diols to sugars. • CTH can be successfully applied to a large variety of reducing sugars. [ABSTRACT FROM AUTHOR]

The synthesis of nanoporous hydrated zirconia catalysts was studied for application in the hydrothermal conversion of monosaccharides and biomass sources. The synthesis was carried out by sol-gel method using zirconium n-propoxide and Pluronic P123 as precursor and template, respectively. Different synthesis solvents, water (W), ethanol (E) and isopropanol (I), as well as different template removal methods, including thermal treatments and solvent refluxing extraction, were investigated. Physicochemical properties were determined by N 2 sorption, TEM, XRD, FTIR and potentiometric titration. Catalysts synthesized in alcoholic solvents by refluxing extraction exhibited high surface areas (320–360 m2/g) and pore volumes (0.20–0.43 cm3/g), which comprised large micropores and mesopores, and obtained the most outstanding acidic properties. A strong influence of the synthesis solvent on the amount and strength of acid sites was found, following the order I > E > W. This behavior was explained by different ratios between the basic terminal and acidic bridging Zr–OH bonds formed on hydrated zirconia. In tune with superior acidic and textural properties, promising mass yields towards lactic acid from a glucose, xylose and arabinose mixture (34.8 %), glyceraldehyde (83.36 %), starch (17.1 %) and wheat bran (18.3 %), were attained with the catalyst synthesized in isopropanol. [Display omitted] • ZrO 2 prepared in alcoholic solvents by refluxing extraction showed high surface areas. • There is strong relationship between the solvent and the amount and strength of acid sites. • Lactic acid yields between 17.1 and 83.4 % were achieved with different raw materials. • Model mixtures of sugars, starch, and wheat bran were used as reagents. [ABSTRACT FROM AUTHOR]

• Semi-continuous subcritical hydrolysis of orange wastes to obtaining fermentable sugars. • Yields for platform chemicals (organic acids, furfural, and HMF) are also addressed. • Effects of biomass pretreatment (extraction by soxhlet e supercritical CO 2) were discussed. • 5.3 g/100 g orange peel of hydrolyzed solution was obtained at 180 °C and 15 MPa. • Also, 4.3 g/100 g orange bagasse of hydrolyzed solution was obtained at 200 °C and 20 MPa. Results for the obtaining of fermentable sugars (FSs) and platform chemicals (PCs) from the subcritical hydrolysis of orange wastes (peel and bagasse) are presented. Unlike what is typically reported in similar studies involving lignocellulosic biomasses, the hydrolysis process was performed in a semi-continuous configuration, which allowed the examination of how temperature (180 to 220 °C) and pressure (15 to 25 MPa) influenced the compounds' kinetic profile. Furthermore, studies have been found that evaluated these points for such biomasses. The best yields of hydrolyzed solution were obtained for biomasses pretreated by soxhlet with hydrolysis conducted at 180 °C and 15 MPa (orange peel, OP) and 200 °C and 20 MPa (orange bagasse, OB), yielding 5.31 and 4.26 g (100 g biomass)−1, respectively. Among the FSs, xylose was the monosaccharide predominantly obtained for both biomasses: 21.12 g L −1 for OP pretreated with SCO 2 (hydrolysis at 180 °C and 15 MPa); and 24.45 g L −1 for untreated OB (hydrolysis at 220 °C and 25 MPa). Regarding the PCs, furfural was the main compound obtained for both biomasses: 10.86 g L −1 for untreated OP and 7.33 g L −1 for OB pretreated with SCO 2 , with both hydrolysis conducted at 220 °C and 25 MPa. [Display omitted] [ABSTRACT FROM AUTHOR]

Particulate matter 2.5 (PM2.5) is associated with reproductive health and adverse pregnancy outcomes. However, studies evaluating biological markers of PM2.5 are lacking, and identifying biomarkers for estimating prenatal exposure to prevent pregnancy complications is essential. Therefore, we aimed to explore urine metabolites that are easy to measure as biomarkers of exposure. In this matched case-control study based on the PM2.5 exposure, 30 high PM2.5 group (>15 μg/m3) and 30 low PM2.5 group (<15 μg/m3) were selected from air pollution on pregnancy outcome (APPO) cohort study. We used a time-weighted average model to estimate individual PM exposure, which used indoor PM2.5 and outdoor PM2.5 concentrations by atmospheric measurement network based on residential addresses. Clinical characteristics and urine samples were collected from participants during the second trimester of pregnancy. Urine metabolites were quantitatively measured using gas chromatography-mass spectrometry following multistep chemical derivatization. Statistical analyses were conducted using SPSS version 21 and MetaboAnalyst 5.0. Small for gestational age and gestational diabetes (GDM) were significantly increased in the high PM2.5 group, respectively (P = 0.042, and 0.022). Fifteen metabolites showed significant differences between the two groups (P < 0.05). Subsequent pathway enrichment revealed that four pathways, including pentose and glucuronate interconversion with three pentose sugars (ribose, arabinose, and xylose; P < 0.05). The concentration of ribose increased preterm births (PTB) and GDM (P = 0.044 and 0.049, respectively), and the arabinose concentration showed a tendency to increase in PTB (P = 0.044). Therefore, we identified urinary pentose metabolites as biomarkers of PM2.5 and confirmed the possibility of their relationship with pregnancy complications. ● Fifteen metabolites associated with exposure to particulate matter were identified. ● Ribose concentration is associated with preterm births and gestational diabetes. ● Urinary metabolites as biomarkers for evaluating prenatal exposure. [ABSTRACT FROM AUTHOR]

[Display omitted] • A P. putida strain was engineered to utilize xylose via the Weimberg pathway. • An adaptive laboratory-evolved strain showed similar growth on both glucose and xylose. • Identified key mutations responsible for higher growth on xylose through Weimberg pathway. • A reverse-engineered strain capable of co-utilization of glucose and xylose was constructed. • The engineered P. putida produced 29 g/L of 3HP from glucose and xylose in fed-batch fermentation. Pseudomonas putida , a robust candidate for lignocellulosic biomass-based biorefineries, encounters challenges in metabolizing xylose. In this study, Weimberg pathway was introduced into P. putida EM42 under a xylose-inducible promoter, resulting in slow cell growth (0.05 h−1) on xylose. Through adaptive laboratory evolution, an evolved strain exhibited highly enhanced growth on xylose (0.36 h−1), comparable to that on glucose (0.39 h−1). Whole genome sequencing identified four mutations, with two key mutations located in PP3380 and PP2219. Reverse-engineered strain 8EM42_Xyl, harboring these two mutations, showed enhanced growth on xylose but co-utilizing glucose and xylose at a rate of 0.3 g/L/h. Furthermore, 8EM42_Xyl was employed for 3-hydroxypropionic acid (3HP) production from glucose and xylose by expressing malonyl-CoA reductase and acetyl-CoA carboxylase, yielding 29 g/L in fed-batch fermentation. Moreover, the engineered strain exhibited promising performance in 3HP production from empty palm fruit bunch hydrolysate, demonstrating its potential as a promising cell factory for biorefineries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developed method termed SEPME to rapidly identify and remove pathway bottlenecks. • SEPME revealed effects of in vivo enzyme expression level on pathway flux. • SEPME detected and tracked shifts in bottlenecks in xylose-to-ethanol pathway. • Five iterations of SEPME yielded xylose-to-ethanol conversion efficiency of >90 %. Engineering microbes that can efficiently ferment xylose to ethanol is critical to the development of renewable fuels from lignocellulosic biomass. To accelerate the strain optimization process, a method termed Segmentation and Evaluation of Pathway Module Efficiency (SEPME) was developed to enable rapid and iterative identification and removal of metabolic bottlenecks. Using SEPME, the overall pathway was segmented into two modules: the upstream xylose assimilation pathway and the downstream pentose phosphate pathway, glycolysis, and fermentation. The efficiencies of both modules were then quantified to identify the rate controlling module, followed by analyses of control coefficients, reaction rates, and byproduct concentrations to narrow down targets within the module. SEPME analysis revealed that as the strain was engineered with increasing xylose-to-ethanol yields, the bottlenecks shifted within a module and across the two modules. Guided by SEPME, these bottlenecks were removed one by one, and a strain approaching the theoretical ethanol yield was obtained. [ABSTRACT FROM AUTHOR]

Clostridium autoethanogenum can to convert waste gases (CO 2 , CO, H 2) and xylose from hydrolyzed biomass into acetate, lactate, formate, ethanol and 2,3-butanediol, being a candidate for the transformation of waste streams of lignocellulosic biorefineries. Electro-fermentation (EF) modify the pattern of traditional fermentations resulting in improved product yields as has been shown when using Clostridium strains. The aim of this work was to evaluate the influence of pH on microbial growth and product distribution during fermentation and EF of xylose by C. autoethanogenum DSM10061. Fermentation and EF were carried out in a H-type reactor at three controlled pH: 5.0, 5.5 and 5.8, and at a fixed potential of −600 mV (versus Ag/AgCl) in the EF. The experiments showed that maximum biomass concentration increased as the pH increased in fermentation and EF. In accordance with maximum biomass reached, the highest substrate conversion was observed at pH 5.8 for both systems, with 76.80 % in fermentation and 96.18 % in EF. Moreover, the highest concentrations of acetic acid (1.41 ± 0.07 g L−1) and ethanol (1.45 ± 0.15 g L−1) were obtained at the end of cultures in the EF at pH 5.8. The production of lactic and formic acid decreased by the application of the external potential regardless of the pH value, reaching the lowest productivity at pH 5.8. In contrast, the specific productivity of acetic acid and ethanol was lower in both fermentation and EF at the lowest pH. Furthermore, the presence of 0.06 g L−1 of 2,3-butanediol was only detected in EF at pH 5.8. The results revealed that EF modulated microbial metabolism, which can be explained by a possible increased generation of NADP+/NADPH cofactors, which would redirect the metabolic pathway to more reduced products. [Display omitted] • Effect of pH on fermentation and electro-fermentation of xylose by C. autoethanogenum was evaluated. • The production of acetic acid and ethanol was increased at pH 5.8. • The production of lactic acid was increased at pH 5.0. • The electro-fermentation increased the mean specific rate of ethanol production. [ABSTRACT FROM AUTHOR]

Co-fermentation of multiple substrates has emerged as the most effective method to improve the yield of bioproducts. Herein, sustainable rubberwood enzymatic hydrolysates (RWH) were co -fermented by Aureobasidium pullulans to produce poly(β-L-malic acid) (PMA), and RWH + glucose/xylose was also investigated as co-substrates. Owing to low inhibitor concentration and abundant natural nitrogen source content of RWH, a high PMA yield of 0.45 g/g and a productivity of 0.32 g/L/h were obtained by RWH substrate fermentation. After optimization, PMA yields following the fermentation of RWH + glucose and RWH + xylose reached 59.92 g/L and 53.71 g/L, respectively, which were 52 % and 36 % higher than that after the fermentation of RWH. RWH + glucose more significantly affected the correlation between PMA yield and substrate concentration than RWH + xylose. The results demonstrated that the co-fermentation of RWH co-substrate is a promising method for the synthesis of bioproducts. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-yield mucic acid production by genetically engineered Saccharomyces cerevisiae. • NAD+-dependent uronate dehydrogenase and xylose-metabolic pathway were expressed. • Xylose metabolism enables NAD+ regeneration for uronate dehydrogenase. • The highest productivity was demonstrated with citrus peel waste. Mucic acid holds promise as a platform chemical for bio-based nylon synthesis; however, its biological production encounters challenges including low yield and productivity. In this study, an efficient and high-yield method for mucic acid production was developed by employing genetically engineered Saccharomyces cerevisiae expressing the NAD+-dependent uronate dehydrogenase (udh) gene. To overcome the NAD+ dependency for the conversion of pectin to mucic acid, xylose was utilized as a co-substrate. Through optimization of the udh expression system, the engineered strain achieved a notable output, producing 20 g/L mucic acid with a highest reported productivity of 0.83 g/L-h and a theoretical yield of 0.18 g/g when processing pectin-containing citrus peel waste. These results suggest promising industrial applications for the biological production of mucic acid. Additionally, there is potential to establish a viable bioprocess by harnessing pectin-rich fruit waste alongside xylose-rich cellulosic biomass as raw materials. [ABSTRACT FROM AUTHOR]

Second generation bioethanol represents an important biofuel, but innovations on biomass pre-treatment and fermentation are needed to improve efficiency and cost-effectiveness in its production. In this work, beech wood chips were treated using an acetone-based organosolv fractionation process at pilot scale, resulting in the isolation of lignin, a high-purity cellulosic pulp and a liquid stream containing hemicellulose sugars. The hemicellulose stream (C5 stream) contained xylose as major sugar and also contained fermentation inhibitors such as furanics, organic acids and phenolics. The cellulosic pulp was enzymatically hydrolysed producing a glucose-rich stream (C6 stream). These streams were used as fermentation substrates by the yeasts Saccharomyces cerevisiae and Spathaspora passalidarum , in separate cultures. Addition of ammonium phosphate or of yeast extract and peptone (YP) as nitrogen sources improved yeast growth. The C6 stream was readily fermentable. When at a sugar concentration of 192 g L−1 and supplemented with YP, the ethanol titre reached 91 g L−1, with a yield of 0.49 g ethanol per g consumed sugars. The C5 stream required detoxification to achieve fermentability. In detoxified C5 stream, S. passalidarum produced 0.46 g ethanol per gram consumed sugars. Fermentation of the resulting streams at 10-L scale confirmed the results obtained at laboratory scale. As alternative approach, sequential fermentation of the C5 stream by S. passalidarum followed by C6 stream addition and inoculation with S. cerevisiae resulted in almost complete sugar utilization and an ethanol yield of 0.41 g per gram consumed sugar albeit with a lower ethanol productivity. [Display omitted] • Fermentable sugar streams produced from beech wood chips by upscaled acetone fractionation. • Fermentation of glucose-rich and xylose-rich streams validated at 10-L scale. • High ethanol titre (10 %, w/v) and yield (95 %) were obtained from lignocellulosic beech wood C6 sugars. • Ethanol was produced from detoxified beech wood C5 sugar stream at a titre of 3 % (w/v) and 70 % yield. [ABSTRACT FROM AUTHOR]

• Dielectric properties of D-xylose aqueous mixtures in the frequency range 1 mHz-10 MHz has been reported. • Differential scanning calorimeter are also used to explore the thermal behaviour of aqueous mixture. • The critical concentration of water observed in D-xylose aqueous solutions shows moderate characteristics as compared to its isomers viz. D-ribose, D-arabinose and D-lyxose are discussed. • The Tg of bulk water are estimated from the extrapolation of DSC Tg and dielectric Tg of the D-xylose aqueous mixture using the Gordon-Taylor equation. D-xylose aqueous solutions at various concentrations of water (0 ≤ x ≤ 40 %) were investigated using broadband dielectric spectroscopy and differential scanning calorimeter in the wide temperature range (150–300 K). Two resolvable relaxations were observed in all studied D-xylose aqueous solutions. The slower relaxation process (process-I) observed above the glass transition temperature (T g), usually referred to as the structural relaxation process, is responsible for the collective movement of the D-xylose and water mixture. The faster one (process-II) observed below T g is mainly related to the water molecular relaxation inside the D-xylose matrix. The temperature dependence of the average dielectric relaxation time and dielectric strength of both observed processes (I & II) were analyzed for all concentrations of water (x) in D-xylose. It was observed that the dielectric strength of process-II in the D-xylose water mixture increased sharply above critical concentration, x = 25 % shows moderate characteristics as compared to its isomers viz. D-ribose, D-arabinose and D-lyxose. Also the activation energies were found to be almost water content independent above critical concentration, x = 25 %. This suggests that this dynamic process was dominated by water-water interaction. Moreover, the T g of bulk water was estimated at 133 ± 1 K and 138 ± 1.2 K from the extrapolation of DSC T g and dielectric T g, respectively of the D-xylose aqueous mixture using the Gordon-Taylor equation. This gives further support to the commonly accepted T g value of bulk water. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1,4-Dioxane works as an ingenious and practical solvent in converting C5 and C6 sugars to furfural. • The synergistic action of Hβ zeolite and 1,4-dioxane/H 2 O system promotes furfural production. • Glucose-to-furfural through 3-deoxyglucose should be more favorable than that via fructose. • One-pot catalytic conversion of glucose and xylose mixtures gains a furfural yield as high as 63%. • The activation energy barrier for furfural production is higher from glucose compared to xylose. The simultaneous valorization of biomass-based C5 and C6 sugars to furfural, a versatile intermediate, is of great significance to fully utilize biomass components. Inability to effectively transform C6 sugars remains a major barrier toward this challenging goal. We herein report the 1,4-dioxane-mediated solvent system with Hβ zeolite catalyst for the transformation of glucose giving high yield to furfural (57%). The maintenance of intrinsic balanced Lewis and Brønsted acid sites from Hβ zeolite that is credited to the positive solvent effect of 1,4-dioxane is highly conductive to the selective C-C bond cleavage of glucose. Also importantly, the introduction of proper amount of H 2 O into the reaction system results in a high formation rate and an improved selectivity toward furfural due to the induction of highly reactive acyclic glucose. Glucose-to-furfural through 3-deoxyglucose should be more favorable than that via fructose. Impressively, the developed protocol can also be adapted to C5 sugars dehydration, and the one-pot conversion of glucose and xylose mixtures gains a furfural yield as high as 63%. The activation energy barrier for furfural production is higher from glucose compared to xylose. This work not only develops a promising protocol for furfural production simultaneously from C5 and C6 sugars but also provides insights into the mechanistic role of the solvent 1,4-dioxane to availably manipulate the acid-catalyzed conversion of C6 sugars. [ABSTRACT FROM AUTHOR]

Xylose is the second most abundant sugar in nature and conversion of xylose to xylonic acid (XA) has become a research hotspot in recent years. Xylonic acid can be applied in the equivalent market niche of gluconic acid, due to their similar physical properties. XA bioproduction and application presents certainly a promising approach for xylose valorization in lignocellulose biorefinery, while the XA crystallization is so far still an unattainable goal. In this paper, an original method was proposed and experimentally investigated for the first time to get XA crystals from fermentation broth. In the XA crystallization, methanol was introduced as buffer-cum-solvent. The H 2 SO 4 was dropwise added into the methanol solution dissolving potassium xylonate that is beforehand produced by fermentation. During H 2 SO 4 blending with methanol, the strong and polar H 2 SO 4 leads to XA diffusion and aggregation. Overall, 2.21 g of xylonic acid crystals was obtained per gram of 98% H 2 SO 4 acidification. NMR detection showed that over 99% purity of XA crystals was finally obtained at the yields of 67.2% from xylonate. The integrated process could provide a practicable and effective technology for the high-qualify XA preparation from xylose derivations and lignocellulose biomass biorefinery. • Xylonic acid crystallization exists bottleneck. • Sulfuric acid addition leads to XA crystallization in methanol. • 99% purity of XA crystal was obtained. [ABSTRACT FROM AUTHOR]