Hydrolysis Of Inulin Research Articles

Inactivation of sacB Gene Allows Higher 2,3-Butanediol Production by Bacillus licheniformis from Inulin

Bacillus licheniformis 24 (BL24) is an efficient, non-pathogenic producer of 2,3-butanediol (2,3-BD). However, during inulin fermentation, the strain produces large amounts of exopolysaccharides (EPS), which interfere with the process’ performance. The present study aims to investigate the effect that inactivation of the sacB gene, encoding levansucrase in BL24, has on 2,3-BD production efficiency. Knockout of the sacB gene was accomplished via insertional inactivation. The sacB-knockout variant formed 0.57 g/L EPS from sucrose and 0.7–0.8 g/L EPS from glucose and fructose, a 15- and 2.5-fold reduction relative to the wild type, respectively. Likewise, during batch fermentation with soluble inulin Frutafit® CLR, the mutant BLΔsacB produced significantly less EPS than the wild type, allowing the maintenance of pH at values favoring 2,3-BD synthesis. At pH 6.50, BLΔsacB reached a record titer of 128.7 g/L 2,3-BD, with productivity of 1.65 g/L/h, and a yield of 85.8% of the theoretical maximum. The obtained concentration of 2,3-BD is two-fold higher compared to that of the wild type. Subsequent RT-qPCR assays confirmed a successful sacB knockout. Three of the genes involved in inulin hydrolysis (sacA, sacC, and fruA) maintained their expression levels compared to the wild type, while that of levB increased. Although total EPS accumulation could not be completely eliminated via sacB gene knockout alone, the overall reduction in EPS content has enabled the highest yield of 2,3-BD from inulin to date, a promising result for the industrial production from inulin-rich substrates.

Characterization of a salt-tolerated exo-fructanase from Microbacterium sp. XL1 and its application for high fructose syrup preparation from inulin

Exo-fructanase enzymes catalyze the hydrolysis of β-2,6 and β-2,1 linkages in levan and inulin fructans, respectively, yielding fructose. In this study, we identified a multidomain exo-fructanase, Mle3A, from Microbacterium sp. XL1. Mle3A is a 124.2 kDa protein comprising a GH32 N-terminal five-bladed β-propeller structure, a GH32 C-terminal β-sandwich module, and a fibronectin type 3 domain. The recombinant enzyme rMle3A exhibited peak activity at temperatures of 50–55 °C and a pH of 5.5, demonstrating hydrolytic capabilities towards levan, inulin, sucrose, and raffinose. The activity of rMle3A on inulin was enhanced in the presence of Mn2+, Ca2+, Ba2+, Sr2+, Co2+, and Mg2+ ions. Notably, 5 mM Mn2+ increased the inulin hydrolytic activity of rMle3A by over 187 %, and the enzyme's activity was unaffected by NaCl concentrations ranging from 0 to 3 M. Purified rMle3A was effectively utilized to produce high fructose syrup from inulin, achieving a maximum fructose concentration of 26.98 g/L and 71.9 % inulin hydrolysis under optimal conditions (85 rpm, 50 °C, pH 5.5) within 2.5 h. This study introduces a new salt-tolerant, multi-ion facilitated fructanase, rMle3A, for the conversion of inulin biomass into high fructose syrup and other high-value chemicals.

Utilization of Yacon Damaged Roots as a Source of FOS-Enriched Sweet-Tasting Syrup

Damaged yacon roots, often discarded, are a rich source of sweet carbohydrates. In this context, yacon roots from the Hualqui and Crespo varieties were characterized and processed into low-calorie and low-glycemic syrups for sugar reduction in foods. Syrups were obtained using, as technological adjuvants, lemon juice and its most relevant components: citric acid and ascorbic acid. The Hualqui variety was found to be mostly composed of fructose (210 g/kg), while the Crespo variety was rich in inulin (352 g/kg). The use of lemon juice during syrup production promoted the hydrolysis of inulin to fructooligosaccharides and fructose, yielding syrups with competitive relative sweetness (0.52–0.91), glycemic index (0.21–0.40), and caloric values (186–263 kcal/100 g) to commercial syrups. The increase in citric acid concentrations promoted inulin hydrolysis, yielding, at the highest concentration, syrups with higher fructose (333–445 g/kg) and kesto-type fructooligosaccharides (11–85 g/kg) content and lower surface stickiness and stringiness. The addition of ascorbic acid, as an antioxidant agent, decreased by 10% the free sugar content, negatively impacting the sweetness level. These results evidence that fructooligosaccharides-rich syrup can be obtained from yacon-damaged roots with tailored sweetness and low glycemic and caloric properties.

Determination of optimum temperatures and activation energies of inulin hydrolysis by endo-inulinase Aspergillus niger

Determination of optimum temperatures and activation energies of inulin hydrolysis by endo-inulinase Aspergillus niger

Properties of the extracellular alkaline inulinase produced by haloalkaliphilic phototrophic bacteria Ectothiorodospirea mobilis.

The studies have revealed alkaline exoinulinase produced by haloalkaliphilic phototrophic bacteria Ectothiorhodospirea mobilis Al-2 for the first time. A new method for the isolation of a homogeneous exoinulinase from the culture broth was developed and the properties of this enzyme have been investigated. It was shown that specified exoinulinase in contrast to the studied exoinulinases produced by microorganisms exhibits catalytic activity at the wide range of pH (7.0-10) and a temperature (20-60°C) with a maximum of the inulolitic activity at pH 9.0 and 50°C. The studied exoinulinase possessing also invertase activity (I/S1.4) is a monomeric protein with molecular mass 57Kda, as well as Km and Vmax for inulin 3.8mM/ml and 10µmol/ml/min-1, respectively. The studies of the influence of different metal ions on enzyme activity have shown that Mn+2, Cu+2,Co+2,Mg+2, NaCl 5-7% promote relatively higher catalytic activity while Zn+2, Cu+2and Fe+2partially suppress the enzyme activity and Hg2+completely inactivates the enzyme.The formation of only fructose and glucose at the enzymatic hydrolysis of inulin confirms that the studied exoinulinase belongs to the exo-type of enzymes. The obtained results supplement our fundamental knowledge in biochemistry-enzymology, as well as the biodiversity of microorganisms expressing exoinulinase. The studied exoinulinase exhibits activity at salinity of the medium and can potentially be used in the biotechnology of inulin bioconversion into bioproducts under alkaline conditions.

Stabilization of elements of secondary structure in Aspergillus awamori exo-inulinase for thermostability improvement

Enzymes with high thermostability provide bioconversion under elevated temperatures during industrial processes. Additional improvement in the enzyme thermostability allows further increasing the temperature for cost reduction. Aspergillus awamori exo-inulinase is sufficiently thermostable to hydrolyze inulin at temperatures up to 70 °C during the industrial process of bioconversion of the polysaccharide inulin into high-fructose syrup. Amino acid substitutions S322P and T521P were designed to improve the thermostability of A. awamori exo-inulinase and increase the temperature of the hydrolysis. The substitutions provided stabilization of α-helix and β-sheet as detected with molecular dynamics simulations at 70 °C. The substitution S322P also provided stabilization of the cleft of the active center, which correlated with the improvement in the thermostability of the enzyme. The variant S322P demonstrated a 1.5-fold increase in thermostability at 70 °C and a 2 °C increase in the temperature of inulin hydrolysis.

Optimization of Inulin Extraction from Chicory Roots and an Ultrafiltration Application to Obtain Purified Inulin and Hydrolyzed Fructooligosaccharides

Inulin and fructooligosaccharides (FOS) are prominent functional components in the food industry due to prebiotic and other pharmaceutical properties. Inulin is a storage polysaccharide in various plants. FOS are naturally present in various plants and can be obtained by partial hydrolysis of inulin. In this study, ground and sieved chicory roots (Cichorium intybus L.) were used as starting material for inulin extraction under optimized conditions determined by Response Surface Methodology (RSM) with a Box-Behnken design. Optimum inulin extraction conditions from chicory roots were; temperature of 90 °C, extraction time of 30 min., and liquid-to-solid (LS) ratio of 10:1 mL/g. Inulin extract was further hydrolyzed to FOS by enzymatic or acid treatment, separately. Purification of inulin extract and FOS hydrolysate was performed by ultrafiltration with a 10 kDa membrane under the pressure of 2 bar with continuous stirring. As a result, inulin and FOS were obtained at 90% and 76% purity, respectively.

Influence of pH on Inulin Conversion to 2,3-Butanediol by Bacillus licheniformis 24: A Gene Expression Assay.

2,3-Butanediol (2,3-BD) is an alcohol highly demanded in the chemical, pharmaceutical, and food industries. Its microbial production, safe non-pathogenic producer strains, and suitable substrates have been avidly sought in recent years. The present study investigated 2,3-BD synthesis by the GRAS Bacillus licheniformis 24 using chicory inulin as a cheap and renewable substrate. The process appears to be pH-dependent. At pH 5.25, the synthesis of 2,3-BD was barely detectable due to the lack of inulin hydrolysis. At pH 6.25, 2,3-BD concentration reached 67.5 g/L with rapid hydrolysis of the substrate but was accompanied by exopolysaccharide (EPS) synthesis. Since inulin conversion by bacteria is a complex process and begins with its hydrolysis, the question of the acting enzymes arose. Genome mining revealed that several glycoside hydrolase (GH) enzymes from different CAZy families are involved. Five genes encoding such enzymes in B. licheniformis 24 were amplified and sequenced: sacA, sacB, sacC, levB, and fruA. Real-time RT-PCR experiments showed that the process of inulin hydrolysis is regulated at the level of gene expression, as four genes were significantly overexpressed at pH 6.25. In contrast, the expression of levB remained at the same level at the different pH values at all-time points. It was concluded that the sacC and sacA/fruA genes are crucial for inulin hydrolysis. They encode exoinulinase (EC 3.2.1.80) and sucrases (EC 3.2.1.26), respectively. The striking overexpression of sacB under these conditions led to increased synthesis of EPS; therefore, the simultaneous production of 2,3-BD and EPS cannot be avoided.

One-Pot Tandem Transformation of Inulin as Fructose-Rich Platform Towards 5-Hydroxymethylfurfural: Feedstock Advantages, Acid-Site Regulation and Solvent Effects.

The valorization of non-grain biomass feedstocks to value-added chemicals, polymers and alternative fuels is a crucial route for the utilization of renewable resources. Inulin belongs to a type of fructans, which is a pivotal platform bridging upstream fructose-rich biomass feedstocks typically represented by Jerusalem artichoke and downstream platform molecules such as alcohols, aldehydes and acids. Fructose can be directly obtained from the inulin hydrolysis and further converted into various platform chemicals, which is a more environmentally economical route than the conventional catalytic upgrading of cellulose. Nevertheless, most perspectives over the last decade have focused on the valorization of cellulose-derived carbohydrates, without much emphasis on the practical importance of one-pot transformation of inulin. In this review, we aim to demonstrate an efficient one-pot tandem transformation system of the inulin as fructose-rich platform towards 5-hydroxymethylfurfural (HMF). Core concerns are placed on elucidating the contributing roles of acid sites and solvents in enhancing the overall catalytic performance. The perspectives presented in this review may contribute to the innovation in the catalytic refining of fructose-rich non-grain biomass and the development of a greener biomass-based energy system.

Use of Tunable Copolymers in Aqueous Biphasic Systems for Extractive Bioconversion Aimed at Continuous Fructooligosaccharide Production

Aqueous biphasic systems (ABSs) based on sodium polyacrylate (NaPA), ethylene oxide/propylene oxide (EO/PO) polymers, and (EO)x-(PO)y-(EO)x triblock copolymers were prepared and applied aiming at continuous fructooligosaccharide (FOS) production and separation. EO/PO hydrophilicity/hydrophobicity balance had a significant effect on ABS formation. To develop an integrated process including the continuous enzymatic (levansucrase) production of FOSs and their purification while improving the production yield by further glucose separation, the potential of these novel polymer-based ABSs as alternative platforms was investigated. They were used for the partitioning of different carbohydrates (FOS, sucrose, d-fructose, and d-glucose) and levansucrase. Results revealed a highly polymer-dependent partition of carbohydrates and a poorly dependent one of the enzymes. Changing EO/PO and copolymers, FOS was purified with high yields (72.94–100.0%). Using polypropylene glycol 400 + NaPA 8000-based ABS, the FOS was precipitated in the interphase and separated from the other components. Pluronic PE-6800 + NaPA 8000 was identified as the best ABS for FOS continuous production and in situ purification, while minimizing levansucrase inhibition by d-glucose. This system allowed selective partition of FOSs and d-glucose toward the top phase and that of levansucrase and its substrates toward the bottom one. COnductor-like Screening MOdel for Real Solvent (COSMO-RS) suggested that ABS formation may have been due to NaPA and polymer/copolymer competition to form hydrogen bonds with water molecules. Moreover, the partition of FOSs and sugar may have been the result of a subtle balance between hydrogen bonding of sugar and polymer/copolymer and electrostatic misfit of solute with NaPA. Finally, two integrated processes were proposed to be applied with real FOS extracts obtained by chemical or enzymatic hydrolysis of inulin or by transfructosylation of concentrated sucrose solutions using bacterial levansucrases.

Kinetic and thermodynamic aspects of the process of thermal inactivition of kluyveromyces marxianus inulinase

Background: Inulinase is widely found in microorganisms and higher plants. It catalyzes the reaction of the hydrolysis of inulin, which is present in the tubers and roots of many plants, to fructose and a small amount of glucose.
 Inulin is one of several plant-based polysaccharides that contain glucose or fructose. It is used as a substrate in industrial fermentation processes and in the food industry due to its relatively cheap and abundant source for the microbiological production of high fructose juices, ethanol, acetone and butanol. Inulin-derived oligosaccharides are also used in the medical and food sectors. Inulinase which produced from the yeast K. marxianus at levels close to commercial use. This indicates that inulinase can be used in the production of fructose and fructose syrups. So our main object is to study the effect of different temperatures on the conformation of the Kluyveromyces marxianus inulinase macromolecule, to provide optimal conditions for aniline hydrolysis by inulinase.
 Materials and method: Method of isolation and purification of the inulinase enzyme from Kluyveromyces marxianus, as well as the determination of the protein content and enzyme activity as mentioned in the context of the research. Experiments were carried out to study the thermal stability of enzyme. For this, an enzyme solution at a concentration of 5•10-5 mol / l was incubated in a time interval of 10-60 min at different temperatures, followed by determination of the catalytic activity.
 It is known that different types of bonds and interactions participate in the formation of the molecular structure of enzymes, which are covalent bonds, hydrogen bonds, salt bridges, hydrophobic interactions, so our main goal is to study the effect of different temperatures on the formation of the enzyme molecule in order to provide optimal conditions for aniline hydrolysis. by enzyme.
 Results: of this study revealed that the residual activity of the enzyme after 60 minutes of incubation at 50 °C was 10% of the initial activity at 60 °C 7%. As for the Rate Constants of thermal inactivation of Inulinase at 70 °C were 3.45.
 Conclusions: Results of this study were important and useful in determining parameters of inulinase enzyme. Based on the shape of the curves of the dependence of the catalytic activity of Kluyveromyces marxianus inulinase on the time of thermal inactivation in the temperature range of 20-80 ° C.

Single substitution in α-helix of active center enhanced thermostability of Aspergillus awamori exo-inulinase

Exo-inulinases are applied in inulin hydrolysis and production of feed additives and need to be stable at temperatures of 60–95 °C. Aspergillus awamori exo-inulinase Inu1 is considerably thermostable, with a Tm of 73.2 °C. However, the thermostability of the enzyme should be improved. A single substitution G338A in α-helix in the active center of the enzyme provided a 3.5 °C improvement in Tm. The time of half-life at 70 °C and 80 °C was increased in 5.7- and 2.7-times, respectively, compared to wild-type. Molecular dynamics simulations demonstrated that the substitution G338A caused a decrease in RMSF not only for the α-helix 337-YAANI-341, but also for the catalytically active residues D41 and E241 and the amino acid residues forming the cleft of the active center. Calculations with Constraint Network Analysis for the variant G338A showed the increase in the stability of intramolecular clusters.

Production, Biochemical Characterization, and Kinetic/Thermodynamic Study of Inulinase from Aspergillus terreus URM4658.

Inulinases are enzymes involved in the hydrolysis of inulin, which can be used in the food industry to produce high-fructose syrups and fructo-oligosaccharides. For this purpose, different Aspergillus strains and substrates were tested for inulinase production by solid-state fermentation, among which Aspergillus terreus URM4658 grown on wheat bran showed the highest activity (15.08 U mL−1). The inulinase produced by this strain exhibited optimum activity at 60 °C and pH 4.0. A detailed kinetic/thermodynamic study was performed on the inulin hydrolysis reaction and enzyme thermal inactivation. Inulinase was shown to have a high affinity for substrate evidenced by very-low Michaelis constant values (0.78–2.02 mM), which together with a low activation energy (19.59 kJ mol−1), indicates good enzyme catalytic potential. Moreover, its long half-life (t1/2 = 519.86 min) and very high D-value (1726.94 min) at 60 °C suggested great thermostability, which was confirmed by the thermodynamic parameters of its thermal denaturation, namely the activation energy of thermal denaturation (E*d = 182.18 kJ mol−1) and Gibbs free energy (106.18 ≤ ΔG*d ≤ 111.56 kJ mol−1). These results indicate that A. terreus URM4658 inulinase is a promising and efficient biocatalyst, which could be fruitfully exploited in long-term industrial applications.

Aspergillus welwitschiae inulinase enzyme cocktails obtained on agro-material inducers for the purpose of fructooligosaccharides production

Production of fructooligosaccharides (FOS) is a trending topic due to their prebiotic effect becoming increasingly important for the modern human diet. The most suitable process for FOS production is the one using fungal inulinases. Introduction of new fungal inulinase producers and their implementation in production of inulinase enzymes is therefore gaining interest. This study provides a new approach to FOS synthesis by fungal enzyme complex without prior separation of any specific enzyme. Inulinase enzyme complexes could be used for the synthesis of FOS in two possible ways – hydrolysis of inulin (FOSh) and transfructosylation process of sucrose (FOSs), as demonstrated here. Depending on the fungal growth inducing substrate, a variety of inulinase enzyme complexes was obtained – one of which was most successful in production of FOSh and another one of FOSs. Substrates derived from crops: triticale, wheat bran, Jerusalem artichoke and Aspergillus welwitschiae isolate, previously proven as safe for use in food, were utilized for production of inulinase enzyme cocktails. The highest FOSs production was obtained by enzyme complex rich in β-fructofuranosidase, while the highest FOSh production was obtained by enzyme complex rich in endoinulinase. Both FOSh and FOSs showed antioxidant potential according to ABTS and ORAC, which classifies them as a suitable additive in functional food. Simultaneous zymographic detection of inulinase enzymes, which could contribute to expansion of the knowledge on fungal enzymes, was developed and applied here. It demonstrated the presence of different inulinase isoforms depending on fungal growth substrate. These findings, which rely on the innate ability of fungi to co-produce all inulinases from a cocktail, could be useful as a new, easy approach to FOS production by fungal enzymes without their separation and purification, contributing to cheaper and faster production processes.

A novel approach to inulin depolymerization: A Monte Carlo based model

• Monte Carlo model for inulin depolymerization. • End-biting/internal random cleavage mechanism was adopted. • The detailed molecular weight distribution can be simulated. • The model can distinguish between two scission mechanisms. • The obtained kinetic parameters are in line with literature. Modelling the depolymerization of natural and synthetic polymers is still a challenge in the field of chemical reaction engineering, as the classical approaches based on complex consecutive/parallel reaction mechanisms show limited capabilities in predicting phenomena that nature would do statistically. A Kinetic Monte Carlo model is proposed, which assumes that polymers can be cleaved following two parallel reaction mechanisms: (i) end-biting (i.e., unzipping), (ii) internal random cleavage. The model was studied via a systematic parametric investigation, and it showed high flexibility in predicting detailed product distribution and concentration profiles of monomers as a function of reaction time. The model was applied to a industrially interesting case: inulin hydrolysis, giving mostly fructose as reaction product. A very good fit was obtained and the model was capable to explain the often-overlooked details observed in the experimental results, e.g., the sigmoidal kinetics in the early stages of the hydrolysis and its dependence on experimental conditions.

A comparative study between Fusarium solani and Neocosmospora vasinfecta revealed differential profile of fructooligosaccharide production.

Fructooligosaccharides (FOS) are fructose-based oligosaccharides employed as additives to improve the food's nutritional and technological properties. The rhizosphere of plants that accumulate fructopolysaccharides as inulin has been revealed as a source of filamentous fungi. These fungi can produce FOS either by inulin hydrolysis or by biosynthesis from sucrose, including unusual FOS with enhanced prebiotic properties. Here, we investigated the ability of Fusarium solani and Neocosmospora vasinfecta to produce FOS from different carbon sources. Fusarium solani and N. vasinfecta grew preferentially in inulin instead of sucrose, resulting in the FOS production as the result of endo-inulinase activities. N. vasinfecta was also able to produce the FOS 1-kestose and 6-kestose from sucrose, indicating transfructosylating activity, absent in F. solani. Moreover, the results showed how these carbon sources affected fungal cell wall composition and the expression of genes encoding for β-1,3-glucan synthase and chitin synthase. Inulin and fructose promoted changes in fungal macroscopic characteristics partially explained by alterations in cell wall composition. However, these alterations were not directly correlated with the expression of genes related to cell wall synthesis. Altogether, the results pointed to the potential of both F. solani and N. vasinfecta to produce FOS at specific profiles.

One-pot hydrolytic hydrogenation of carbohydrates to hexitols catalyzed by Ru loaded P and Si-containing hierarchical porous biochars with excellent catalytic efficiency

The one-pot hydrolytic hydrogenation of carbohydrates to sugar alcohols is one of the important value-added transformations of biomass, but the hydrolysis efficiency of carbohydrates in this one-pot conversion is still limited by the high cleavage energy of their β-1,4-glycosidic bonds and the concomitant serious side-reactions. Therefore, it is necessary to develop the new acidic carriers to improve the key first-step hydrolysis. This paper discloses that a forestry processing waste bamboo powder can be converted into the P and Si-containing porous biochar (PSBC) via inserting silica sol, impregnating concentrated phosphoric acid (H3PO4) and heating carbonization. Due to the improved porosity and strong acidity of PSBC and its affinity to β-1,4-glycosidic bonds, this new acid carrier exhibits an outstanding catalysis performance for the hydrolysis of cellulose, cellobiose, especially sucrose and inulin, affording ca. 76.2% glucose yield in cellulose hydrolysis at 150 °C. More importantly, PSBC can efficiently and uniformly load Ru nanometer particles (average size of 1.5 nm) to fabricate 1%Ru/PSBC as an excellent bifunctional catalyst for the one-pot conversion of these carbohydrates to hexitols, affording ca. 85.2% hexitols with 51.7 h−1 turnover frequency in the one-pot conversion of cellulose under 150 °C and 3 MPa H2 pressure. This work not only provides an effective strategy for the preparation of biomass-derived bifunctional catalysts, but also it opens up new voyages for the development of efficient bio-refining.Graphical abstractRu-loaded P and Si-containing porous biochar (1% Ru/PSBC) is an excellent bifunctional catalyst for the hydrolytic hydrogenation of carbohydrates under relatively mild conditions, affording ca. 85.2% hexitols with 51.7 h−1 TOF in the one-pot conversion of cellulose.

Escherichia coli Strains from Patients with Inflammatory Bowel Diseases have Disease-specific Genomic Adaptations.

Escherichia coli is over-abundant in the gut microbiome of patients with inflammatory bowel disease [IBD]. Here, we aimed to identify IBD-specific genomic functions of diverse E. coli lineages. We investigated E. coli genomes from patients with ulcerative colitis [UC], Crohn's disease [CD] or a pouch, and healthy subjects. The majority of genomes were reconstructed from metagenomic samples, including newly sequenced faecal metagenomes. Clinical metadata were collected. Functional analysis at the gene and mutation level were performed and integrated with IBD phenotypes and biomarkers. Overall, 530 E. coli genomes were analysed. The E. coli B2 lineage was more prevalent in UC compared with other IBD phenotypes. Genomic metabolic capacities varied across E. coli lineages and IBD phenotypes. Host mucin utilisation enzymes were present in a single lineage and depleted in patients with a pouch, whereas those involved in inulin hydrolysis were enriched in patients with a pouch. E. coli strains from patients with UC were twice as likely to encode the genotoxic molecule colibactin than strains from patients with CD or a pouch. Strikingly, patients with a pouch showed the highest inferred E. coli growth rates, even in the presence of antibiotics. Faecal calprotectin did not correlate with the relative abundance of E. coli. Finally, we identified multiple IBD-specific non-synonymous mutations in E. coli genes encoding for bacterial cell envelope components. Comparative genomics indicates that E. coli is a commensal species adapted to the overactive mucosal immune milieu in IBD, rather than causing it. Our results reveal mutations that may lead to attenuated antigenicity in some E. coli strains.

Efficient production of inulo-oligosaccharides from inulin by exo- and endo-inulinase co-immobilized onto a self-assembling protein scaffold

Inulin can be hydrolyzed by inulinases to yield inulo-oligosaccharides (IOSs), which have great application potential in the food and nutraceutical industries. However, conventional enzymatic production of IOSs is limited by long hydrolysis times and poor thermo-stability of inulinases. Here, the self-assembling protein scaffold EutM was engineered to co-immobilize exo-inulinase (EXINU) and endo-inulinase (ENINU) for synergistic hydrolysis of inulin to produce IOSs with 3 to 5 monosaccharide units (DP3–5 IOSs). The immobilization of EXINU/ENINU onto the EutM scaffold resulted in an increase of catalytic efficiency, a 65% increase of the Vmax of ENINU, as well as an increase of thermo-stability, with 4.26-fold higher residual activity of EXINU after 22 h-incubation at 50 °C. After optimization, two efficient production protocols were obtained, in which the yield and productivity of DP3–5 IOSs reached 80.38% and 70.86 g·(L·h)−1, respectively, which were at a high level in similar studies. Overall, this study provides an attractive self-assembling protein platform for the co-immobilization of inulinases, as well as optimized bioprocesses with great promise for the industrial production of DP3–5 IOSs.

An integrated ionic liquid hybrid polymeric fixed-bed reactor with a porous sponge-like structure for biomass hydrolysis

Biomass hydrolysis into fermentable reducing sugars is essential for the bioethanol production. Novel integrated ionic liquid (IL) hybrid polymeric fixed-bed reactor with porous sponge-like structure was constructed for inulin hydrolysis. The acidic IL, [(CH2)3SO3HVIm]HSO4 was covalently grafted on polysulfone (PSF). The PSF-ILs integrated porous fixed beds were elaborately prepared by famous non-solvent induced phase separation approach. Effects of coagulation bath composition and temperature, fixed bed height, permeation flux, feed temperature and concentration on inulin hydrolysis were explored intensively. The porous sponge-like structure and chemical binding of ILs endowed the fixed beds with excellent catalytic performance, stability, and reusability. Under optimized conditions, once the inulin aqueous solution permeated through the fixed beds, the yield of total reducing sugar (TRS) reached up to 98.82%. Compared with the catalytic membrane, the hydrolysis reaction time was drastically shortened by 92.5%. These findings provided a new strategy on developing high-performance fixed-bed reactors for biomass conversion.