Biotechnology and Bioprocess Engineering最新文献

Abstract

Erythritol as a four-carbon polyol has been widely used in food, pharmaceutical and daily chemical industries with characteristics of low caloric value and high chemical stability. Here, a system metabolic engineering strategy was used to increase the yield of erythritol from glycerol in Yarrowia lipolytica by enhancing the substrate transformation and restricting the by-product synthesis. Specifically, we determined that over-expression of a newly identified erythrose reductase YPR1 was able to improve the erythritol production as same as the well-known erythrose reductase ER27. Instead of its up-regulation, knockout of erythrose reductase ER10 was effective to improve erythritol synthesis. Moreover, both over-expression of YPR1 and deletion of ER10 significantly accelerated the glycerol utilization in response to high osmotic stress. To further decrease the by-product accumulation, a restriction and recycling strategy was implemented by knockout of mannitol dehydrogenase MDH2 and enhancement of arabitol dehydrogenase ADH1 and fructokinase HXK1. The engineered strain YL13 produced a titer of 25 g/L erythritol and less than 0.5 g/L mannitol and arabitol. By over-expression of transketolase TKL1, the final strain YL14 produced 28.5 g/L erythritol and none of mannitol and arabitol. This study provides a new idea for reducing the production of by-products and improving the glycerol conversion to erythritol.

Flavonoid consists of an extensive range of compounds with variable inhibitory activities against alpha-glucosidase, implicating its role in the prevention and treatment of diabetes caused by uncontrolled increases in the blood glucose level. Comprehensive study on a selected assortment of flavonoids for their degrees of inhibition, types of inhibitory mode and the structure–function relationship both in terms of the ligand chemical structure and in the context of the enzyme–inhibitor binding complex is therefore necessary to predict and develop efficient flavonoid inhibitors. Herein, flavonoids based on flavone, flavonol, flavanone and isoflavone skeletons in their aglycone and glycone forms were analyzed to this purpose. Most aglycones showed excellent inhibition, while glycones showed relatively low activities. Competitive, noncompetitive and mixed inhibition modes were observed from different types of flavonoids, and their molecular mechanisms by binding to the active or allosteric sites of alpha-glucosidase were analyzed via the docking study. Quercetin with a superior competitive inhibitory activity bound near the catalytic residues within the active site, whereas other glycosylated quercetin derivatives bound at more distal sites. Mixed inhibitors resulted in opposite binding conformations in the allosteric site depending on whether they show more competitive-like or uncompetitive-like behaviors, while the noncompetitive inhibitor could bind in both conformations.

Seaweed biomass in Korea is rich in galactose following hydrolysis, and leveraging this resource for enhancing the biohydrogen production is the aim of this study. The study investigates the biohydrogen production potential of a newly isolated pure strain, Clostridium sp. JH03, utilizing galactose and seaweed biomass as renewable feedstocks. The strain could utilize galactose as the sole carbon source for biohydrogen production, with a maximum hydrogen yield of 1.61 mol H₂/mol galactose. The parameters included pH, temperature, and initial galactose concentration, which were varied to determine the optimal conditions for maximum biohydrogen production. The optimal conditions for biohydrogen production were pH 9 and a temperature of 25 °C, with an initial galactose concentration of 10 g/L. Moreover, hydrogen production from seaweed hydrolysate by Clostridium sp. JH03 resulted in maximum production of 1.71 mol H₂/mol galactose. The study also investigated that combining sludge, a common practice in dark fermentation, with JH03 increased biohydrogen production by up to 34%. By addressing the need for clean energy and reducing raw materials price using biomass, this study contributes to the advancement of sustainable and cost-compatible energy solutions.

6-Aminocaproic acid and adipic acid are the key value-added chemical precursors in the pharmaceutical, solvent and polyamide industry, including nylon-6, and nylon-6, 6. An enzymatic interconversion of the two precursors can provide a convenient and eco-friendly biosynthetic route to each of the precursors and thus, require analysis of the reaction process. Herein, an in vitro enzymatic method was employed to convert the two precursors while most studies so far have focused on the whole cell bioconversion to investigate the process. 4-Aminobutyrate aminotransferase was utilized to mediate the reactions between 6-aminocaproic acid and the intermediate 6-oxohexanoic acid with the aid of pyridoxal 5’-phosphate and amine donor/acceptor. 6-Oxohexanoate dehydrogenase was utilized for the reaction from 6-oxohexanoic acid to adipic acid with NADP⁺. A range of reaction conditions were investigated including the type of amine donor, pH conditions, the concentrations of enzyme and amine donor/acceptor. The optimum condition resulted in 78% yield for the reaction from 6-oxohexanoic acid to 6-aminocaproic acid. The yield for the one-pot, two-step enzymatic cascade from 6-aminocaproic acid via 6-oxohexanoate intermediate to adipic acid was 88%, which was higher than the yield for each individual step in the cascade, with 31% and 32%, for the first and second step, respectively. Furthermore, structural analysis on the active site of the 4-aminobutyrate aminotransferase docked with a range of amine donors implicates the optimal donor is glutamate in accordance with the experimental data and suggests enzyme engineering possibilities for more readily available donors to facilitate the industrial application of the process.

Brown algae have gained attention as a sustainable feedstock for biorefineries due to their ability to sequester carbon dioxide, rapid growth, and high carbohydrate content. The carbohydrate content in brown algae has only been analyzed for a few species, and in most cases, access to fundamental data such as sugar composition is limited, which hinders the assessment of brown algal biomass-based biorefining potential. In this study, the carbohydrate composition of brown algae (Undaria pinnatifida, Saccharina japonica, Ecklonia cava, and Ecklonia stolonifera) was analyzed in detail and application directions were proposed. As a result, alginate and glucan were detected in all resources, and the contents (alginate and glucan wt%) were as follows: U. pinnatifida (39.6 and 4.9 wt%), S. japonica (34.0 and 6.3 wt%), E. cava (24.3 and 7.7 wt%), and E. stolonifera (39.1 and 9.7 wt%). All feedstocks contain trace amounts (2.9–4.9 wt%) or no xylan-mannan-galactan. Mannitol was detected only in S. japonica (26.7 wt%) in rich, showing high potential as a biorefinery feedstock. We highlight that the carbohydrate composition of E. cava and E. stolonifera was analyzed for the first time and the potential use of brown algal biomass in a biorefinery approach.

The threats of air pollution mediated by particulate matter (PM) to human health are severe burdens to modern society. For example, PM is inhaled in the lungs or affects keratinocytes to induce reactive oxygen species that exert oxidative stress, inflammatory responses, and genotoxicity. Natural products are rich sources of the antioxidant and anti-inflammatory chemicals that might counteract what PM does in the human body. This review provides a compilation of knowledge on bioactive natural products that improve the health conditions from PM-induced health outcomes. The natural products were classified according to biosynthetic origins or resources: phenolic compounds including flavonoids and other phenolics, terpenoids, steroids, phytochemicals from marine algae, statins, lipids, alkaloids, and other nitrogen-containing natural products. This review article covers the structures and biological activity of natural products investigated with tissue cells or animal models.

Drug repurposing is a rapidly growing for the development of new therapeutic agents. Among them, phosphodiesterase-5 (PDE5) inhibitors, which show excellent effects as a treatment for erectile dysfunction, have been continuously reported for their potential as anti-cancer agents. It is necessary to apply targeted delivery systems to enhance the efficacy of the PDE5 inhibitors (PDE5i) as anti-cancer drugs. In this study, PDE5 inhibitor-binding domain (PBD) was developed to incorporate PDE5i into antibody using biological affinity binding without any chemical modifications. The PBD spontaneously bound with PDE5i, resulting in the formation of PBD/PDE5i complex. We also constructed a recombinant fusion protein composed of an anti-HER2 scFv and PBD (HER2 scFv-PBD) to deliver the PDE5i for the treatment of HER2 positive cancer cells. HER2 scFv-PBD could deliver the PDE5i into HER2-positive cancer cells and enhanced anti-cancer effect of the PDE5i. We have demonstrated the potential of tumor-directed PDE5 inhibition as a novel form of targeted therapy using drug binding fusion proteins.

The natural polyphenolic materials that cinnamon contains are well known for their different biological applications and have a wide variety of pharmacological and therapeutic attributes. Bioactive and harmless cinnamon nanoparticles (cinnamon-NPs) can be anticancer and antidiabetic agents. For this purpose, water-soluble cinnamon-NPs were synthesized using the hydrothermal technique for the first time and in vitro studies were performed to investigate their anti-diabetic effects. The outcomes of morphology, size, and stability of cinnamon-NPs were described through Transmission electron microscopy (TEM), X-ray diffraction (XRD), Dynamic light scattering/Zeta (DLS/Zeta), Ultraviolet–visible (UV–Vis), and Fourier transform infrared (FTIR) analyses. The morphology of cinnamon-NPs was spherical and their average size was about 14.8 nm. Furthermore, the glucose consumption assay results revealed that compound cinnamon-NPs at 1.0 and 10 µM significantly lowered glucose levels (p < 0.05) in HepG2 cells exposed to 11.0 and 22.0 mM of glucose compared with standard (pioglitazone) and control groups. Therefore, the utilization of spherical NPs suspended in water could be useful for investigating therapeutic applications.

Food waste is a huge problem worldwide, and spoilage during storage is a major contributor. Food freshness monitoring systems can help reduce food waste by providing consumers with information to more accurately predict the shelf life of their food. In the case of milk, pH can be used as a freshness indicator. As milk spoils, microbial activity converts lactose to lactic acid, which produces hydrogen ions (H⁺) and consequently lowers the pH of the milk. In this paper, we propose a paper sensor that can detect the pH of milk in a refrigerated state (− 4 ℃) by color change. Polydiacetylene (PDA)/zinc oxide (ZnO) nanocomposite, which changes its color from blue to red as the pH decreases, was used as the color changing material. Specifically, the nanocomposite was applied to a nitrocellulose (NC) membrane, which is approved as a food packaging material for monitoring freshness during transport or on the shelf. The freshness monitoring function of the sensor was verified by applying artificially spoiled milk samples to the PDA/ZnO@NC membrane. In particular, it was demonstrated that the PDA/ZnO@NC membrane was shown to detect spoiled milk samples with pH 4.5 in 10 min at low temperature. Furthermore, the color change of the sensor upon detection of spoilage remained stable even after long-term storage. In conclusion, the PDA/ZnO@NC membrane presented in this study can be widely applied to the freshness monitoring of various food products stored at low temperatures whose spoilage is evaluated by pH.

The present work demonstrates the biosynthesis of silver nanoparticles (AgNPs) using Coffea arabica leaf extract. The AgNPs prepared by green route from C. arabica leaf were characterized through UV–visible, X-ray diffraction, transmission electron microscopy and energy-dispersive electron spectroscopy. Later, the prepared NPs were conjugated with cysteamine–folic acid and utilized as a contrast medium for in vitro targeted imaging of folic acid receptor-expressing malignant cells by computerized tomography (CT). At 80 kVp, the targeted cells exhibited CT values which were two times greater than that of the non-targeted cells. The results were compared with the folic acid-negative cell lines as well as the effective inhibition of folic acid receptor using free folic acid substrate. The outcome of the present study suggests that the fabricated cysteamine–folic acid-conjugated silver nanoparticles could be utilized as a potential contrast agent for molecular CT imaging. This information can be taken into consideration for applying AgNPs in enhancing radiation dose where nanoparticles containing greater X-ray attenuation were applied.