Solvent-dependent strategy to construct mesoporous Zr-based metal-organic frameworks for high-efficient adsorption of tetracycline.

The accumulated antibiotics in the aquatic environment pose great threat to human and ecological health, boosting the development of porous materials for antibiotic removal. Mesoporous metal-organic frameworks (MOFs) have shown great promise in adsorption, which, however, usually need supramolecular design or cooperative template strategy for synthesis. Here we report the successful construction of mesoporous zirconium based metal-organic frameworks (Zr-MOFs) via a simple solvent-dependent strategy. Regulation of the ratio of water to N, N-dimethylacetamide during synthesis determined the porous structure of the synthesized MOFs. Systematic characterizations including SEM, FTIR, XRD and nitrogen sorption isotherm were carried out for structure analysis of the MOFs. With water fraction of 20% (v/v), the obtained Zr-MOF exhibited the highest adsorption capacity (Qmax of 337.0 mg⋅g-1) towards tetracycline (TC). The adsorption kinetics fitted the pseudo-second-order kinetics, and the adsorption isotherms fitted the Freundlich model well. Adsorption mechanism investigation revealed that the abundant Zr-OH groups stemming from coordination defects mainly accounted for TC adsorption. The hydrogen bonding interaction between TC and Zr-MOF and the generated mesopores contributed to the satisfactory adsorption capacity. This work is anticipated to provide insights on facile synthesis of mesoporous MOFs and application in environmental remediation.

1,4-α-Glucosidase from Fusarium solani for Controllable Biosynthesis of Silver Nanoparticles and Their Multifunctional Applications.

In the study, monodispersed silver nanoparticles (AgNPs) with an average diameter of 9.57 nm were efficiently and controllably biosynthesized by a reductase from Fusarium solani DO7 only in the presence of ß-NADPH and polyvinyl pyrrolidone (PVP). The reductase responsible for AgNP formation in F. solani DO7 was further confirmed as 1,4-α-glucosidase. Meanwhile, based on the debate on the antibacterial mechanism of AgNPs, this study elucidated in further depth that antibacterial action of AgNPs was achieved by absorbing to the cell membrane and destabilizing the membrane, leading to cell death. Moreover, AgNPs could accelerate the catalytic reaction of 4-nitroaniline, and 86.9% of 4-nitroaniline was converted to p-phenylene diamine in only 20 min by AgNPs of controllable size and morphology. Our study highlights a simple, green, and cost-effective process for biosynthesizing AgNPs with uniform sizes and excellent antibacterial activity and catalytic reduction of 4-nitroaniline.

A Versatile Competitive Coordination Strategy for Tailoring Bioactive Zeolitic Imidazolate Framework Composites.

Zeolitic imidazolate frameworks (ZIFs) serving as platforms for bioactive guest encapsulation have attracted growing attention, yet the tailoring of its architectures and bioactivity remains a major challenge. Herein, a versatile competitive coordination strategy is proposed by using amorphous zinc nucleotide gel as template for step-by-step growth of ZIFs, which enables the tailoring of bioactive ZIF composites under facile conditions. Mechanism investigation reveals that introduced nucleotide determines the hierarchical pore structure and hydrophilicity, leading to customized activity retention and stability of the resultant bioactive ZIF composites. Furthermore, nucleoside monophosphate enhances the acidic tolerance of ZIFs. To the authors' knowledge, this is the first example showing the dynamic evolution of amorphous gels to crystalline ZIFs for in situ encapsulation of enzymes with tailored catalytic performance. This study provides insights for rational design of ZIF-based biocomposites and broadens the application of bioactive metal-organic frameworks.

Biotechnology and bioengineering of pullulanase: state of the art and perspectives.

Pullulanase (EC 3.2.1.41) is a starch-debranching enzyme in the α-amylase family and specifically cleaves α-1,6-glycosidic linkages in starch-type polysaccharides, such as pullulan, ß-limited dextrin, glycogen, and amylopectin. It plays a key role in debranching and hydrolyzing starch completely, thus bring improved product quality, increased productivity, and reduced production cost in producing resistant starch, sugar syrup, and beer. Plenty of researches have been made with respects to the discovery of either thermophilic or mesophilic pullulanases, however, few examples meet the demand of industrial application. This review presents the progress made in the recent years from the first aspect of characteristics of pullulanases. The heterologous expression of pullulanases in different microbial hosts and the methods used to improve the expression effectiveness and the regulation of enzyme production are also described. Then, the function evolution of pullulanases from a protein engineering view is discussed. In addition, the immobilization strategy using novel materials is introduced to improve the recyclability of pullulanases. At the same time, we indicate the trends in the future research to facilitate the industrial application of pullulanases.

Discovery of dipeptidyl peptidase 4 inhibitory peptides from Largemouth bass (Micropterus salmoides) by a comprehensive approach.

Dipeptidyl peptidase-4 (DPP4) is the prime target for glycemic control by inactivating glucagon-like peptide and decreasing postprandial glucose levels. Food protein-derived peptides have been considered to be capable of inhibiting DPP4. In this study, a novel strategy was developed by coupling in silico gastrointestinal digestion, pharmacophore and three-dimensional quantitative structure-activity relationships (3D-QSAR) analysis to discover DPP4 inhibitory peptide, and in vitro assay was confirmed. Specifically, the simulated gastrointestinal hydrolysis was firstly performed on Largemouth bass (Micropterus salmoides) proteins, the generated peptides were used to establish peptide library. Secondly, 60 DPP4 inhibitors were selected and pharmacophore model was generated; moreover, 40 DPP4 inhibitory tripeptides were collected to construct 3D-QSAR model. Thirdly, the pharmacophore and 3D-QSAR models were employed to screen the above peptide library. Lastly, the in vitro activity assay was performed, which showed that the six tripeptides (VSM, ISW, VSW, ICY, ISD and ISE) exhibited inhibitory activities on DPP4, and ICY was the most active tripeptide with the IC50 value of 0.73 mM. This is the first identification of Largemouth bass protein-derived peptides as DPP4 inhibitor, which is good for the development of food protein-derived peptides with glucose lowering activity.

Microbial synthesis of functional odd-chain fatty acids: a review.

Odd-chain fatty acids (OCFAs) naturally occur in bacteria, higher animals, and in plants. During recent years, they have received increasing attention due to their unique pharmacological properties and usefulness for agricultural and industrial applications. Recently, OCFAs have been identified and quantified in a few organisms, and new pharmacological functions of OCFAs have been reported. Some of the publications are related to the optimization of OCFA production through fermentation and genetic engineering. The present review aims to provide a summary on the recent progress in the field of microbial-derived OCFAs. More specifically, we outline the publications of OCFAs related to (i) different sources of OCFAs; (ii) endogenous synthesis of OCFAs; (iii) production of OCFAs through fermentation; (iv) genetic engineering related to OCFA; and (v) role of OCFAs in human health and disease. Finally, some areas that require further research are discussed.

Metabolic engineering of a robust Escherichia coli strain with a dual protection system.

Considerable attention has been given to the development of robust fermentation processes, but microbial contamination and phage infection remain deadly threats that need to be addressed. In this study, a robust Escherichia coli BL21(DE3) strain was successfully constructed by simultaneously introducing a nitrogen and phosphorus (N&P) system in combination with a CRISPR/Cas9 system. The N&P metabolic pathways were able to express formamidase and phosphite dehydrogenase in the host cell, thus enabled cell growth in auxotrophic 3-(N-morpholino)propanesulfonic acid medium with formamide and phosphite as nitrogen and phosphorus sources, respectively. N&P metabolic pathways also allowed efficient expression of heterologous proteins, such as green fluorescent protein (GFP) and chitinase, while contaminating bacteria or yeast species could hardly survive in this medium. The host strain was further engineered by exploiting the CRISPR/Cas9 system to enhance the resistance against phage attack. The resultant strain was able to grow in the presence of T7 phage at a concentration of up to 2 × 107 plaque-forming units/ml and produce GFP with a yield of up to 30 µg/109 colony-forming units, exhibiting significant advantages over conventional engineered E. coli. This newly engineered, robust E. coli BL21(DE3) strain therefore shows great potential for future applications in industrial fermentation.

Using 1-propanol to significantly enhance the production of valuable odd-chain fatty acids by Rhodococcus opacus PD630.

Odd-chain fatty acids (OCFAs) have been reported to possess pharmacological activity and have been used in the manufacture of agricultural and industrial chemicals. We here provided a new method to increase the OCFAs content in oil produced by Rhodococcus opacus PD630 through addition of 1-propanol to the fermentation media. The OCFAs in oil of R. opacus PD630 are primarily pentadecanoic acid (C15:0), heptadecanoic acid (C17:0) and heptadecenoic acid (C17:1). After adding 0.5-1.5% (v/v) 1-propanol, the production of oil increased from 1.27 g/L to 1.31-1.61 g/L, and the OCFAs content in oil increased by 46.7-55.1%. Metabolic intermediates determination and transcriptome analysis revealed that R. opacus assimilated 1-propanol through methylmalonyl-CoA pathway. When the nitrogen source was limited, propionyl-CoA was converted to propionyl-acyl carrier protein (ACP) which could be used as primer during the elongation of fatty acid synthesis. Then OCFAs were produced when odd number of propionyl-ACP was incorporated in the cycles of fatty acid synthesis.

The application of deep eutectic solvent on the extraction and in vitro antioxidant activity of rutin from Sophora japonica bud.

The extraction conditions and antioxidant activities of rutin from Sophora japonica bud by deep eutectic solvents were investigated. Box-Behnken design was used to optimize the extraction conditions and the scavenging activities of DPPH, O2- and ·OH of purified rutin were evaluated. The highest yield of 279.8 mg/g was achieved in the extraction medium of choline chloride/triethlene glycol (1/4) under the optimum conditions: water content of the DES 18.1%, extraction time 28.3 min, extraction temperature 70 °C and liquid-solid ratio 10 mg/1 g. The highest extraction amount was slightly different from the predicted value of the established second-order polynomial equation. In addition, The EC50 of DPPH scavenging, O2- scavenging and ·OH scavenging of rutin were 5.68 µg/mL, 0.19 and 0.28 mg/mL, respectively. The above results indicate rutin extracted by the choline chloride/triethylene glycol has excellent antioxidant activity and was an admirable free radical scavenger.

Markedly improving asymmetric oxidation of 1-(4-methoxyphenyl) ethanol with Acetobacter sp. CCTCC M209061 cells by adding deep eutectic solvent in a two-phase system.

BACKGROUND: Enantiopure (S)-1-(4-methoxyphenyl) ethanol {(S)-MOPE} can be employed as an important synthon for the synthesis of cycloalkyl [b] indoles with the treatment function for general allergic response. To date, the biocatalytic resolution of racemic MOPE through asymmetric oxidation in the biphasic system has remained largely unexplored. Additionally, deep eutectic solvents (DESs), as a new class of promising green solvents, have recently gained increasing attention in biocatalysis for their excellent properties and many successful examples in biocatalytic processes. In this study, the biocatalytic asymmetric oxidation of MOPE to get (S)-MOPE using Acetobacter sp. CCTCC M209061 cells was investigated in different two-phase systems, and adding DES in a biphasic system was also explored to further improve the reaction efficiency of the biocatalytic oxidation. RESULTS: Of all the examined water-immiscible organic solvents and ionic liquids (ILs), 1-butyl-3-methylimidazolium hexafluorophoshpate ([C4MIM][PF6]) afforded the best results, and consequently was selected as the second phase of a two-phase system for the asymmetric oxidation of MOPE with immobilized Acetobacter sp. CCTCC M209061 cells. For the reaction performed in the [C4MIM][PF6]/buffer biphasic system, under the optimized conditions, the initial reaction rate, the maximum conversion and the residual substrate e.e. recorded 97.8 µmol/min, 50.5 and >99.9 % after 10 h reaction. Furthermore, adding the DES [ChCl][Gly] (10 %, v/v) to the aqueous phase, the efficiency of the biocatalytic oxidation was rose markedly. The optimal substrate concentration and the initial reaction rate were significantly increased to 80 mmol/L and 124.0 µmol/min, respectively, and the reaction time was shortened to 7 h with 51.3 % conversion. The immobilized cell still retained over 72 % of its initial activity after 9 batches of successive reuse in the [C4MIM][PF6]/[ChCl][Gly]-containing buffer system. Additionally, the efficient biocatalytic process was feasible up to a 500-mL preparative scale. CONCLUSION: The biocatalytic asymmetric oxidation of MOPE with Acetobacter sp. CCTCC M209061 cells was successfully conducted in the [C4MIM][PF6]-containing biphasic system with high conversion and enantioselectivity, and the reaction efficiency was further enhanced by adding [ChCl][Gly] to the reaction system. The efficient biocatalytic process was promising for the preparation of enantiopure (S)-MOPE.

Biocatalytic anti-Prelog reduction of prochiral ketones with whole cells of Acetobacter pasteurianus GIM1.158.

BACKGROUND: Enantiomerically pure alcohols are important building blocks for production of chiral pharmaceuticals, flavors, agrochemicals and functional materials and appropriate whole-cell biocatalysts offer a highly enantioselective, minimally polluting route to these valuable compounds. At present, most of these biocatalysts follow Prelog's rule, and thus the (S)-alcohols are usually obtained when the smaller substituent of the ketone has the lower CIP priority. Only a few anti-Prelog (R)-specific whole cell biocatalysts have been reported. In this paper, the biocatalytic anti-Prelog reduction of 2-octanone to (R)-2-octanol was successfully conducted with high enantioselectivity using whole cells of Acetobacter pasteurianus GIM1.158. RESULTS: Compared with other microorganisms investigated, Acetobacter pasteurianus GIM1.158 was shown to be more effective for the reduction reaction, affording much higher yield, product enantiomeric excess (e.e.) and initial reaction rate. The optimal temperature, buffer pH, co-substrate and its concentration, substrate concentration, cell concentration and shaking rate were 35°C, 5.0, 500 mmol/L isopropanol, 40 mmol/L, 25 mg/mL and 120 r/min, respectively. Under the optimized conditions, the maximum yield and the product e.e. were 89.5% and >99.9%, respectively, in 70 minutes. Compared with the best available data in aqueous system (yield of 55%), the yield of (R)-2-octanol was greatly increased. Additionally, the efficient whole-cell biocatalytic process was feasible on a 200-mL preparative scale and the chemical yield increased to 95.0% with the product e.e. being >99.9%. Moreover, Acetobacter pasteurianus GIM1.158 cells were proved to be capable of catalyzing the anti-Prelog bioreduction of other prochiral carbonyl compounds with high efficiency. CONCLUSIONS: Via an effective increase in the maximum yield and the product e.e. with Acetobacter pasteurianus GIM1.158 cells, these results open the way to use of whole cells of this microorganism for challenging enantioselective reduction reactions on laboratory and commercial scales.

Optimizing the Biosynthesis of Dihydroquercetin from Naringenin in Saccharomyces cerevisiae.

Dihydroquercetin (DHQ), known for its varied physiological benefits, is widely used in the food, chemical, and pharmaceutical industries. However, the efficiency of the DHQ synthesis is significantly limited by the substantial accumulation of intermediates during DHQ biosynthesis. In this study, DHQ production was achieved by integrating genes from various organisms into the yeast chromosome for the expression of flavanone-3-hydroxylase (F3H), flavonoid-3'-hydroxylase, and cytochrome P450 reductase. A computer-aided protein design approach led to the development of optimal F3H mutant P221A, resulting in a 1.67-fold increase in DHQ yield from naringenin (NAR) compared with the control. Subsequently, by analysis of the enzyme reaction and optimization of the culture medium composition, 637.29 ± 20.35 mg/L DHQ was synthesized from 800 mg/L NAR. This corresponds to a remarkable conversion rate of 71.26%, one of the highest reported values for DHQ synthesis from NAR to date.

Structural and interfacial properties of acetylated Millettia speciosa Champ polysaccharide and stability evaluation of the resultant O/W emulsion containing ß-carotene.

The aim of this study was to investigate the effects of acetylation modification on the structural, interfacial and emulsifying properties of Millettia speciosa Champ polysaccharide (MSCP). Besides, the influence of acetylation modification on the encapsulation properties of polysaccharide-based emulsion was also explored. Results indicated that modification resulted in a prominent reduction in molecular weight of MSCP and the interfacial layer thickness formed by acetylated MSCP (AC-MSCP) was also decreased, but the adsorption rate and ability of AC-MSCP to reduce interfacial tension were improved. AC-MSCP formulated emulsion possessed smaller droplet size (6.8 µm) and exhibited better physical stability under stressful conditions. The chemical stability of ß-carotene was also profoundly enhanced by AC-MSCP fabricated emulsion. Moreover, AC-MSCP improved lipids digestion extent, thus facilitating the formation of micelle and increasing bioaccessibility of ß-carotene. This study provided insights for rational modification of polysaccharide-based emulsifier and designing delivery system for chemically labile hydrophobic bioactive components.

A review of advancements in chitosan-essential oil composite films: Better and sustainable food preservation with biodegradable packaging.

In response to the environmental pollution caused by non-degradable and non-recyclable plastic packaging films (PPFs) and the resulting health concerns due to the migration of microplastics into food, the development of biodegradable food packaging films has gained great attention. Chitosan has been extensively utilized in the food industry owing to its abundant availability, exceptional biocompatibility, degradability, and antimicrobial properties. Chitosan-essential oil composite films (CEOs) represent a promising avenue to replace conventional PPFs. This review provides an overview of the advancements in CEOs over the past decade, focusing on the effects of essential oils (EOs) on CEOs in terms of antimicrobial activity, antioxidant effect, gas barrier, light barrier, and mechanical properties. It also offers insights into the controlled release of EOs in CEOs and summarizes the application of CEOs in fresh food preservation.

Enzyme-free method for preparation of sturgeon extracts with antioxidant, hepatoprotective and immune-enhancing functions.

Sturgeon has a long lifespan and slow evolutionary rate due to their powerful endogenous antioxidant system. This work aimed to assess the in vitro and in vivo antioxidant activity of sturgeon extracts from both muscle and roe. The extraction process without enzyme hydrolysis is not only simple, but also can produce extracts with better free radicals scavenging abilities than enzymatic hydrolysates in both cellular and in vivo experiments. Moreover, in mouse models with liver injury and immunosuppression treatment, the sturgeon extracts demonstrated strong hepatoprotective and immune-enhancing functions, comparable to vitamin C and ginseng extract supplements, which were attributed to abundant antioxidant peptides of the extracts. The 15 isolated peptides exhibited diverse free radical scavenging ability. Therefore, the sturgeon extracts showed high potential to be applied in food and biomedical industries.

Novel Multitarget ACE Inhibitory Peptides from Bovine Colostrum Immunoglobulin G: Cellular Transport, Efficacy in Regulating Endothelial Dysfunction, and Network Pharmacology Studies.

In this study, we used traditional laboratory methods, bioinformatics, and cellular models to screen novel ACE inhibitory (ACEI) peptides with strong ACEI activity, moderate absorption rates, and multiple targets from bovine colostrum immunoglobulin G (IgG). The purified fraction of the compound proteinase hydrolysate of IgG showed good ACEI activity. After nano-UPLC-MS/MS identification and in silico analysis, eight peptides were synthesized and verified. Among them, SFYPDY, TSFYPDY, FSWF, WYQQVPGSGL, and GVHTFP were identified as ACEI peptides, as they exhibited strong ACEI activity (with IC50 values of 104.7, 80.0, 121.2, 39.8, and 86.3 µM, respectively). They displayed good stability in an in vitro simulated gastrointestinal digestion assay. In a Caco-2 monolayer model, SFYPDY, FSWF, and WYQQVPGSGL exhibited better absorption rates and lower IC50 values than the other peptides and were thereby identified as novel ACEI peptides. Subsequently, in a H2O2-induced endothelial dysfunction (ED) model based on HUVECs, SFYPDY, FSWF, and WYQQVPGSGL regulated ED by reducing apoptosis and ROS accumulation while upregulating NOS3 mRNA expression. Network pharmacology analysis and RT-qPCR confirmed that they regulated multiple targets. Overall, our results suggest that SFYPDY, FSWF, and WYQQVPGSGL can serve as novel multitarget ACEI peptides.

Millettia speciosa Champ cellulose-based hydrogel as a novel delivery system for Lactobacillus paracasei: Its relationship to structure, encapsulation and controlled release.

We report for the first time the usage of Millettia speciosa Champ cellulose (MSCC) and carboxymethylcellulose (MSCCMC) for the fabrication of 3D-network hydrogel as delivery system for probiotics. The structural features, swelling behavior and pH-responsiveness of MSCC-MSCCMC hydrogels and their encapsulation and controlled-release behavior for Lactobacillus paracasei BY2 (L. paracasei BY2) were mainly studied. Structural analyses demonstrated that MSCC-MSCCMC hydrogels with porous and network structures were successfully synthesized through the crosslinking of -OH groups between MSCC and MSCCMC molecules. An increasing concentration of MSCCMC significantly improved the pH-responsiveness and swelling ability of the MSCC-MSCCMC hydrogel toward neutral solvent. Besides, the encapsulation efficiency (50.38-88.91 %) and release (42.88-92.86 %) of L. paracasei BY2 were positively correlated with the concentration of MSCCMC. The higher the encapsulation efficiency was, the higher the release in the target intestine. However, due to the existence of bile salts, controlled-release behavior decreased the survivor rate and physiological state (degrading cholesterol) of encapsulating L. paracasei BY2. Even so, the number of viable cells encapsulated by hydrogels still reached the minimum effective concentration in the target intestine. This study provides an available reference for the practical application of hydrogels fabricated from the cellulose of the Millettia speciosa Champ plant for probiotic delivery.

Light Controlled Nanobiohybrids for Modulating Chiral Alcohol Synthesis.

The modulation of whole-cell activity presents a considerable challenge in biocatalysis. Conventional approaches to whole-cell catalysis, while having their strengths, often rely on complex and deliberate enzyme designs, which could result in difficulties in activity modulation and prolonged response times. Additionally, the activity of intracellular enzymes in whole-cell catalysis is influenced by temperature. To address these limitations, we introduced a relationally designed nanobiohybrid system that utilized light to modulate whole-cell catalysis for chiral alcohol production. By incorporating platinum nanoparticles onto Rhodotorula sp. cell surfaces, the nanobiohybrid capitalized on the photothermal properties of the nanoparticles to regulate the overall cell activity. When exposed to light, the Pt nanoparticles generate heat through the photothermal effect, consequently leading to an increase in the catalytic activity of the whole cells. This innovative approach facilitates control over whole-cell production and provides an efficient method for regulating biocatalytic processes. The findings of this study demonstrate the significant potential of switchable control strategies in biomanufacturing across a wide range of industries.

Co-immobilization of ß-xylosidase and endoxylanase on zirconium based metal-organic frameworks for improving xylosidase activity at high temperature and in acetone.

Improving the activity of ß-xylosidase at high temperature and organic solvents is important for the conversion of xylan, phytochemicals and some hydroxyl-containing substances to produce xylose and bioactive substances. In this study, a ß-xylosidase R333H and an endoxylanase were simultaneously co-immobilized on the metal-organic framework UiO-66-NH2. Compared with the single R333H immobilization system, the co-immobilization enhanced the activity of R333H at high temperature and high concentration of acetone, and the relative activities at 95 °C and 50% acetone solution were >95%. The Km value of co-immobilized R333H towards p-Nitrophenyl-ß-D-xylopyranoside (pNPX) shifted from 2.04 to 0.94 mM, which indicated the enhanced affinity towards pNPX. After 5 cycles, the relative activities of the co-immobilized enzymes towards pNPX and corncob xylan were 52% and 70% respectively, and the accumulated amount of reducing sugars obtained by co-immobilized enzymes degrading corncob xylan in 30% (v/v) acetone solution was 1.7 times than that with no acetone.

Iron-incorporated metal-organic frameworks for oxidative cleavage of trans-anethole to p-anisaldehyde.

An iron-incorporated Zn-MOF catalyst Zn-bpydc·Fe was fabricated for the oxidative cleavage of trans-anethole to p-anisaldehyde under facile conditions, under 1 atm of O2. The Fe coordinated bipyridine serves as the catalytically active center inside the structural skeleton of Zn-MOFs. This work affords a new avenue for the mild oxidation of olefins.